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1 | @setfilename LNEWS |
2 | ||
3 | @section New Features in the Lisp Language | |
4 | ||
5 | @end itemize | |
6 | @itemize @bullet | |
7 | @item | |
8 | The new function @code{delete} is a traditional Lisp function. It takes | |
9 | two arguments, @var{elt} and @var{list}, and deletes from @var{list} any | |
10 | elements that are equal to @var{elt}. It uses the function @code{equal} | |
11 | to compare elements with @var{elt}. | |
12 | ||
13 | @item | |
14 | The new function @code{member} is a traditional Lisp function. It takes | |
15 | two arguments, @var{elt} and @var{list}, and finds the first element of | |
16 | @var{list} that is equal to @var{elt}. It uses the function | |
17 | @code{equal} to compare each list element with @var{elt}. | |
18 | ||
19 | The value is a sublist of @var{list}, whose first element is the one | |
20 | that was found. If no matching element is found, the value is | |
21 | @code{nil}. | |
22 | ||
23 | @ignore @c Seems not to be true, from looking at the code. | |
24 | @item | |
25 | The function @code{equal} is now more robust: it does not crash due to | |
26 | circular list structure. | |
27 | @end ignore | |
28 | ||
29 | @item | |
30 | The new function @code{indirect-function} finds the effective function | |
31 | definition of an object called as a function. If the object is a | |
32 | symbol, @code{indirect-function} looks in the function definition of the | |
33 | symbol. It keeps doing this until it finds something that is not a | |
34 | symbol. | |
35 | ||
36 | @item | |
37 | There are new escape sequences for use in character and string | |
38 | constants. The escape sequence @samp{\a} is equivalent to @samp{\C-g}, | |
39 | the @sc{ASCII} @sc{BEL} character (code 7). The escape sequence | |
40 | @samp{\x} followed by a hexidecimal number represents the character | |
41 | whose @sc{ASCII} code is that number. There is no limit on the number | |
42 | of digits in the hexidecimal value. | |
43 | ||
44 | @item | |
45 | The function @code{read} when reading from a buffer now does not skip a | |
46 | terminator character that terminates a symbol. It leaves that character | |
47 | to be read (or just skipped, if it is whitespace) next time. | |
48 | ||
49 | @item | |
50 | When you use a function @var{function} as the input stream for | |
51 | @code{read}, it is usually called with no arguments, and should return | |
52 | the next character. In Emacs 19, sometimes @var{function} is called | |
53 | with one argument (always a character). When that happens, | |
54 | @var{function} should save the argument and arrange to return it when | |
55 | called next time. | |
56 | ||
57 | @item | |
58 | @code{random} with integer argument @var{n} returns a random number | |
59 | between 0 and @var{n}@minus{}1. | |
60 | ||
61 | @item | |
62 | The functions @code{documentation} and @code{documentation-property} now | |
63 | take an additional optional argument which, if non-@code{nil}, says to | |
64 | refrain from calling @code{substitute-command-keys}. This way, you get | |
65 | the exact text of the documentation string as written, without the usual | |
66 | substitutions. Make sure to call @code{substitute-command-keys} | |
67 | yourself if you decide to display the string. | |
68 | ||
69 | @ignore | |
70 | @item | |
71 | The new function @code{invocation-name} returns as a string the program | |
72 | name that was used to run Emacs, with any directory names discarded. | |
73 | @c ??? This hasn't been written yet. ??? | |
74 | @end ignore | |
75 | ||
76 | @item | |
77 | The new function @code{map-y-or-n-p} makes it convenient to ask a series | |
78 | of similar questions. The arguments are @var{prompter}, @var{actor}, | |
79 | @var{list}, and optional @var{help}. | |
80 | ||
81 | The value of @var{list} is a list of objects, or a function of no | |
82 | arguments to return either the next object or @code{nil} meaning there | |
83 | are no more. | |
84 | ||
85 | The argument @var{prompter} specifies how to ask each question. If | |
86 | @var{prompter} is a string, the question text is computed like this: | |
87 | ||
88 | @example | |
89 | (format @var{prompter} @var{object}) | |
90 | @end example | |
91 | ||
92 | @noindent | |
93 | where @var{object} is the next object to ask about. | |
94 | ||
95 | If not a string, @var{prompter} should be a function of one argument | |
96 | (the next object to ask about) and should return the question text. | |
97 | ||
98 | The argument @var{actor} should be a function of one argument, which is | |
99 | called with each object that the user says yes for. Its argument is | |
100 | always one object from @var{list}. | |
101 | ||
102 | If @var{help} is given, it is a list @code{(@var{object} @var{objects} | |
103 | @var{action})}, where @var{object} is a string containing a singular | |
104 | noun that describes the objects conceptually being acted on; | |
105 | @var{objects} is the corresponding plural noun and @var{action} is a | |
106 | transitive verb describing @var{actor}. The default is @code{("object" | |
107 | "objects" "act on")}. | |
108 | ||
109 | Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or | |
110 | @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip | |
111 | that object; @kbd{!} to act on all following objects; @key{ESC} or | |
112 | @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on | |
113 | the current object and then exit; or @kbd{C-h} to get help. | |
114 | ||
115 | @code{map-y-or-n-p} returns the number of objects acted on. | |
116 | ||
117 | @item | |
118 | You can now ``set'' environment variables with the @code{setenv} | |
119 | command. This works by setting the variable @code{process-environment}, | |
120 | which @code{getenv} now examines in preference to the environment Emacs | |
121 | received from its parent. | |
122 | @end itemize | |
123 | ||
124 | @section New Features for Loading Libraries | |
125 | ||
126 | You can now arrange to run a hook if a particular Lisp library is | |
127 | loaded. | |
128 | ||
129 | The variable @code{after-load-alist} is an alist of expressions to be | |
130 | evalled when particular files are loaded. Each element looks like | |
131 | @code{(@var{filename} @var{forms}@dots{})}. | |
132 | ||
133 | When @code{load} is run and the file name argument equals | |
134 | @var{filename}, the @var{forms} in the corresponding element are | |
135 | executed at the end of loading. @var{filename} must match exactly! | |
136 | Normally @var{filename} is the name of a library, with no directory | |
137 | specified, since that is how @code{load} is normally called. | |
138 | ||
139 | An error in @var{forms} does not undo the load, but does prevent | |
140 | execution of the rest of the @var{forms}. | |
141 | ||
142 | The function @code{eval-after-load} provides a convenient way to add | |
143 | entries to the alist. Call it with two arguments, @var{file} and a | |
144 | form to execute. | |
145 | ||
146 | The function @code{autoload} now supports autoloading a keymap. | |
147 | Use @code{keymap} as the fourth argument if the autoloaded function | |
148 | will become a keymap when loaded. | |
149 | ||
150 | There is a new feature for specifying which functions in a library should | |
151 | be autoloaded by writing special ``magic'' comments in that library itself. | |
152 | ||
153 | Write @samp{;;;###autoload} on a line by itself before a function | |
154 | definition before the real definition of the function, in its | |
155 | autoloadable source file; then the command @kbd{M-x | |
156 | update-file-autoloads} automatically puts the @code{autoload} call into | |
157 | @file{loaddefs.el}. | |
158 | ||
159 | You can also put other kinds of forms into @file{loaddefs.el}, by | |
160 | writing @samp{;;;###autoload} followed on the same line by the form. | |
161 | @kbd{M-x update-file-autoloads} copies the form from that line. | |
162 | ||
163 | @section Compilation Features | |
164 | ||
165 | @itemize @bullet | |
166 | @item | |
167 | Inline functions. | |
168 | ||
169 | You can define an @dfn{inline function} with @code{defsubst}. Use | |
170 | @code{defsubst} just like @code{defun}, and it defines a function which | |
171 | you can call in all the usual ways. Whenever the function thus defined | |
172 | is used in compiled code, the compiler will open code it. | |
173 | ||
174 | You can get somewhat the same effects with a macro, but a macro has the | |
175 | limitation that you can use it only explicitly; a macro cannot be called | |
176 | with @code{apply}, @code{mapcar} and so on. Also, it takes some work to | |
177 | convert an ordinary function into a macro. To convert it into an inline | |
178 | function, simply replace @code{defun} with @code{defsubst}. | |
179 | ||
180 | Making a function inline makes explicit calls run faster. But it also | |
181 | has disadvantages. For one thing, it reduces flexibility; if you change | |
182 | the definition of the function, calls already inlined still use the old | |
183 | definition until you recompile them. | |
184 | ||
185 | Another disadvantage is that making a large function inline can increase | |
186 | the size of compiled code both in files and in memory. Since the | |
187 | advantages of inline functions are greatest for small functions, you | |
188 | generally should not make large functions inline. | |
189 | ||
190 | Inline functions can be used and open coded later on in the same file, | |
191 | following the definition, just like macros. | |
192 | ||
193 | @item | |
194 | The command @code{byte-compile-file} now offers to save any buffer | |
195 | visiting the file you are compiling. | |
196 | ||
197 | @item | |
198 | The new command @code{compile-defun} reads, compiles and executes the | |
199 | defun containing point. If you use this on a defun that is actually a | |
200 | function definition, the effect is to install a compiled version of | |
201 | that function. | |
202 | ||
203 | @item | |
204 | Whenever you load a Lisp file or library, you now receive a warning if | |
205 | the directory contains both a @samp{.el} file and a @samp{.elc} file, | |
206 | and the @samp{.el} file is newer. This typically indicates that someone | |
207 | has updated the Lisp code but forgotten to recompile it, so the changes | |
208 | do not take effect. The warning is a reminder to recompile. | |
209 | ||
210 | @item | |
211 | The special form @code{eval-when-compile} marks the forms it contains to | |
212 | be evaluated at compile time @emph{only}. At top-level, this is | |
213 | analogous to the Common Lisp idiom @code{(eval-when (compile) | |
214 | @dots{})}. Elsewhere, it is similar to the Common Lisp @samp{#.} reader | |
215 | macro (but not when interpreting). | |
216 | ||
217 | If you're thinking of using this feature, we recommend you consider whether | |
218 | @code{provide} and @code{require} might do the job as well. | |
219 | ||
220 | @item | |
221 | The special form @code{eval-and-compile} is similar to | |
222 | @code{eval-when-compile}, but the whole form is evaluated both at | |
223 | compile time and at run time. | |
224 | ||
225 | If you're thinking of using this feature, we recommend you consider | |
226 | whether @code{provide} and @code{require} might do the job as well. | |
227 | ||
228 | @item | |
229 | Emacs Lisp has a new data type for byte-code functions. This makes | |
230 | them faster to call, and also saves space. Internally, a byte-code | |
231 | function object is much like a vector; however, the evaluator handles | |
232 | this data type specially when it appears as a function to be called. | |
233 | ||
234 | The printed representation for a byte-code function object is like that | |
235 | for a vector, except that it starts with @samp{#} before the opening | |
236 | @samp{[}. A byte-code function object must have at least four elements; | |
237 | there is no maximum number, but only the first six elements are actually | |
238 | used. They are: | |
239 | ||
240 | @table @var | |
241 | @item arglist | |
242 | The list of argument symbols. | |
243 | ||
244 | @item byte-code | |
245 | The string containing the byte-code instructions. | |
246 | ||
247 | @item constants | |
248 | The vector of constants referenced by the byte code. | |
249 | ||
250 | @item stacksize | |
251 | The maximum stack size this function needs. | |
252 | ||
253 | @item docstring | |
254 | The documentation string (if any); otherwise, @code{nil}. | |
255 | ||
256 | @item interactive | |
257 | The interactive spec (if any). This can be a string or a Lisp | |
258 | expression. It is @code{nil} for a function that isn't interactive. | |
259 | @end table | |
260 | ||
261 | The predicate @code{byte-code-function-p} tests whether a given object | |
262 | is a byte-code function. | |
263 | ||
264 | You can create a byte-code function object in a Lisp program | |
265 | with the function @code{make-byte-code}. Its arguments are the elements | |
266 | to put in the byte-code function object. | |
267 | ||
268 | You should not try to come up with the elements for a byte-code function | |
269 | yourself, because if they are inconsistent, Emacs may crash when you | |
270 | call the function. Always leave it to the byte compiler to create these | |
271 | objects; it, we hope, always makes the elements consistent. | |
272 | @end itemize | |
273 | ||
274 | @section Floating Point Numbers | |
275 | ||
276 | You can now use floating point numbers in Emacs, if you define the macro | |
277 | @code{LISP_FLOAT_TYPE} when you compile Emacs. | |
278 | ||
279 | The printed representation for floating point numbers requires either a | |
280 | decimal point surrounded by digits, or an exponent, or both. For | |
281 | example, @samp{1500.0}, @samp{15e2}, @samp{15.0e2} and @samp{1.5e3} are | |
282 | four ways of writing a floating point number whose value is 1500. | |
283 | ||
284 | The existing predicate @code{numberp} now returns @code{t} if the | |
285 | argument is any kind of number---either integer or floating. The new | |
286 | predicates @code{integerp} and @code{floatp} check for specific types of | |
287 | numbers. | |
288 | ||
289 | You can do arithmetic on floating point numbers with the ordinary | |
290 | arithmetic functions, @code{+}, @code{-}, @code{*} and @code{/}. If you | |
291 | call one of these functions with both integers and floating point | |
292 | numbers among the arguments, the arithmetic is done in floating point. | |
293 | The same applies to the numeric comparison functions such as @code{=} | |
294 | and @code{<}. The remainder function @code{%} does not accept floating | |
295 | point arguments, and neither do the bitwise boolean operations such as | |
296 | @code{logand} or the shift functions such as @code{ash}. | |
297 | ||
298 | There is a new arithmetic function, @code{abs}, which returns the absolute | |
299 | value of its argument. It handles both integers and floating point | |
300 | numbers. | |
301 | ||
302 | To convert an integer to floating point, use the function @code{float}. | |
303 | There are four functions to convert floating point numbers to integers; | |
304 | they differ in how they round. @code{truncate} rounds toward 0, | |
305 | @code{floor} rounds down, @code{ceil} rounds up, and @code{round} | |
306 | produces the nearest integer. | |
307 | ||
308 | You can use @code{logb} to extract the binary exponent of a floating | |
309 | point number. More precisely, it is the logarithm base 2, rounded down | |
310 | to an integer. | |
311 | ||
312 | Emacs has several new mathematical functions that accept any kind of | |
313 | number as argument, but always return floating point numbers. | |
314 | ||
315 | @table @code | |
316 | @item cos | |
317 | @findex cos | |
318 | @itemx sin | |
319 | @findex sin | |
320 | @itemx tan | |
321 | @findex tan | |
322 | Trigonometric functions. | |
323 | @item acos | |
324 | @findex acos | |
325 | @itemx asin | |
326 | @findex asin | |
327 | @itemx atan | |
328 | @findex atan | |
329 | Inverse trigonometric functions. | |
330 | @item exp | |
331 | @findex exp | |
332 | The exponential function (power of @var{e}). | |
333 | @item log | |
334 | @findex log | |
335 | Logarithm base @var{e}. | |
336 | @item expm1 | |
337 | @findex expm1 | |
338 | Power of @var{e}, minus 1. | |
339 | @item log1p | |
340 | @findex log1p | |
341 | Add 1, then take the logarithm. | |
342 | @item log10 | |
343 | @findex log10 | |
344 | Logarithm base 10 | |
345 | @item expt | |
346 | @findex expt | |
347 | Raise @var{x} to power @var{y}. | |
348 | @item sqrt | |
349 | @findex sqrt | |
350 | The square root function. | |
351 | @end table | |
352 | ||
353 | The new function @code{string-to-number} now parses a string containing | |
354 | either an integer or a floating point number, returning the number. | |
355 | ||
356 | The @code{format} function now handles the specifications @samp{%e}, | |
357 | @samp{%f} and @samp{%g} for printing floating point numbers; likewise | |
358 | @code{message}. | |
359 | ||
360 | The new variable @code{float-output-format} controls how Lisp prints | |
361 | floating point numbers. Its value should be @code{nil} or a string. | |
362 | ||
363 | If it is a string, it should contain a @samp{%}-spec like those accepted | |
364 | by @code{printf} in C, but with some restrictions. It must start with | |
365 | the two characters @samp{%.}. After that comes an integer which is the | |
366 | precision specification, and then a letter which controls the format. | |
367 | ||
368 | The letters allowed are @samp{e}, @samp{f} and @samp{g}. Use @samp{e} | |
369 | for exponential notation (@samp{@var{dig}.@var{digits}e@var{expt}}). | |
370 | Use @samp{f} for decimal point notation | |
371 | (@samp{@var{digits}.@var{digits}}). Use @samp{g} to choose the shorter | |
372 | of those two formats for the number at hand. | |
373 | ||
374 | The precision in any of these cases is the number of digits following | |
375 | the decimal point. With @samp{f}, a precision of 0 means to omit the | |
376 | decimal point. 0 is not allowed with @samp{f} or @samp{g}. | |
377 | ||
378 | A value of @code{nil} means to use the format @samp{%.20g}. | |
379 | ||
380 | No matter what the value of @code{float-output-format}, printing ensures | |
381 | that the result fits the syntax rules for a floating point number. If | |
382 | it doesn't fit (for example, if it looks like an integer), it is | |
383 | modified to fit. By contrast, the @code{format} function formats | |
384 | floating point numbers without requiring the output to fit the | |
385 | syntax rules for floating point number. | |
386 | ||
387 | @section New Features for Printing And Formatting Output | |
388 | ||
389 | @itemize @bullet | |
390 | @item | |
391 | The @code{format} function has a new feature: @samp{%S}. This print | |
392 | spec prints any kind of Lisp object, even a string, using its Lisp | |
393 | printed representation. | |
394 | ||
395 | By contrast, @samp{%s} prints everything without quotation. | |
396 | ||
397 | @item | |
398 | @code{prin1-to-string} now takes an optional second argument which says | |
399 | not to print the Lisp quotation characters. (In other words, to use | |
400 | @code{princ} instead of @code{prin1}.) | |
401 | ||
402 | @item | |
403 | The new variable @code{print-level} specifies the maximum depth of list | |
404 | nesting to print before cutting off all deeper structure. A value of | |
405 | @code{nil} means no limit. | |
406 | @end itemize | |
407 | ||
408 | @section Changes in Basic Editing Functions | |
409 | ||
410 | @itemize @bullet | |
411 | @item | |
412 | There are two new primitives for putting text in the kill ring: | |
413 | @code{kill-new} and @code{kill-append}. | |
414 | ||
415 | The function @code{kill-new} adds a string to the front of the kill ring. | |
416 | ||
417 | Use @code{kill-append} to add a string to a previous kill. The second | |
418 | argument @var{before-p}, if non-@code{nil}, says to add the string at | |
419 | the beginning; otherwise, it goes at the end. | |
420 | ||
421 | Both of these functions apply @code{interprogram-cut-function} to the | |
422 | entire string of killed text that ends up at the beginning of the kill | |
423 | ring. | |
424 | ||
425 | @item | |
426 | The new function @code{current-kill} rotates the yanking pointer in the | |
427 | kill ring by @var{n} places, and returns the text at that place in the | |
428 | ring. If the optional second argument @var{do-not-move} is | |
429 | non-@code{nil}, it doesn't actually move the yanking point; it just | |
430 | returns the @var{n}th kill forward. If @var{n} is zero, indicating a | |
431 | request for the latest kill, @code{current-kill} calls | |
432 | @code{interprogram-paste-function} (documented below) before consulting | |
433 | the kill ring. | |
434 | ||
435 | All Emacs Lisp programs should either use @code{current-kill}, | |
436 | @code{kill-new}, and @code{kill-append} to manipulate the kill ring, or | |
437 | be sure to call @code{interprogram-paste-function} and | |
438 | @code{interprogram-cut-function} as appropriate. | |
439 | ||
440 | @item | |
441 | The variables @code{interprogram-paste-function} and | |
442 | @code{interprogram-cut-function} exist so that you can provide functions | |
443 | to transfer killed text to and from other programs. | |
444 | ||
445 | @item | |
446 | The @code{kill-region} function can now be used in read-only buffers. | |
447 | It beeps, but adds the region to the kill ring without deleting it. | |
448 | ||
449 | @item | |
450 | The new function @code{compare-buffer-substrings} lets you compare two | |
451 | substrings of the same buffer or two different buffers. Its arguments | |
452 | look like this: | |
453 | ||
454 | @example | |
455 | (compare-buffer-substrings @var{buf1} @var{beg1} @var{end1} @var{buf2} @var{beg2} @var{end2}) | |
456 | @end example | |
457 | ||
458 | The first three arguments specify one substring, giving a buffer and two | |
459 | positions within the buffer. The last three arguments specify the other | |
460 | substring in the same way. | |
461 | ||
462 | The value is negative if the first substring is less, positive if the | |
463 | first is greater, and zero if they are equal. The absolute value of | |
464 | the result is one plus the index of the first different characters. | |
465 | ||
466 | @item | |
467 | Overwrite mode treats tab and newline characters specially. You can now | |
468 | turn off this special treatment by setting @code{overwrite-binary-mode} | |
469 | to @code{t}. | |
470 | ||
471 | @item | |
472 | Once the mark ``exists'' in a buffer, it normally never ceases to | |
473 | exist. However, it may become @dfn{inactive}. The variable | |
474 | @code{mark-active}, which is always local in all buffers, indicates | |
475 | whether the mark is active: non-@code{nil} means yes. | |
476 | ||
477 | A command can request deactivation of the mark upon return to the editor | |
478 | command loop by setting @code{deactivate-mark} to a non-@code{nil} | |
479 | value. Transient Mark mode works by causing the buffer modification | |
480 | primitives to set @code{deactivate-mark}. | |
481 | ||
482 | The variables @code{activate-mark-hook} and @code{deactivate-mark-hook} | |
483 | are normal hooks run, respectively, when the mark becomes active andwhen | |
484 | it becomes inactive. The hook @code{activate-mark-hook} is also run at | |
485 | the end of a command if the mark is active and the region may have | |
486 | changed. | |
487 | ||
488 | @item | |
489 | The function @code{move-to-column} now accepts a second optional | |
490 | argument @var{force}, in addition to @var{column}; if the requested | |
491 | column @var{column} is in the middle of a tab character and @var{force} | |
492 | is non-@code{nil}, @code{move-to-column} replaces the tab with the | |
493 | appropriate sequence of spaces so that it can place point exactly at | |
494 | @var{column}. | |
495 | ||
496 | @item | |
497 | The search functions when successful now return the value of point | |
498 | rather than just @code{t}. This affects the functions | |
499 | @code{search-forward}, @code{search-backward}, | |
500 | @code{word-search-forward}, @code{word-search-backward}, | |
501 | @code{re-search-forward}, and @code{re-search-backward}. | |
502 | ||
503 | @item | |
504 | When you do regular expression searching or matching, there is no longer | |
505 | a limit to how many @samp{\(@dots{}\)} pairs you can get information | |
506 | about with @code{match-beginning} and @code{match-end}. Also, these | |
507 | parenthetical groupings may now be nested to any degree. | |
508 | ||
509 | @item | |
510 | The new special form @code{save-match-data} preserves the regular | |
511 | expression match status. Usage: @code{(save-match-data | |
512 | @var{body}@dots{})}. | |
513 | ||
514 | @item | |
515 | The function @code{translate-region} applies a translation table to the | |
516 | characters in a part of the buffer. Invoke it as | |
517 | @code{(translate-region @var{start} @var{end} @var{table})}; @var{start} | |
518 | and @var{end} bound the region to translate. | |
519 | ||
520 | The translation table @var{table} is a string; @code{(aref @var{table} | |
521 | @var{ochar})} gives the translated character corresponding to | |
522 | @var{ochar}. If the length of @var{table} is less than 256, any | |
523 | characters with codes larger than the length of @var{table} are not | |
524 | altered by the translation. | |
525 | ||
526 | @code{translate-region} returns the number of characters which were | |
527 | actually changed by the translation. This does not count characters | |
528 | which were mapped into themselves in the translation table. | |
529 | ||
530 | @item | |
531 | There are two new hook variables that let you notice all changes in all | |
532 | buffers (or in a particular buffer, if you make them buffer-local): | |
533 | @code{before-change-function} and @code{after-change-function}. | |
534 | ||
535 | If @code{before-change-function} is non-@code{nil}, then it is called | |
536 | before any buffer modification. Its arguments are the beginning and end | |
537 | of the region that is going to change, represented as integers. The | |
538 | buffer that's about to change is always the current buffer. | |
539 | ||
540 | If @code{after-change-function} is non-@code{nil}, then it is called | |
541 | after any buffer modification. It takes three arguments: the beginning | |
542 | and end of the region just changed, and the length of the text that | |
543 | existed before the change. (To get the current length, subtract the | |
544 | rrgion beginning from the region end.) All three arguments are | |
545 | integers. The buffer that's about to change is always the current | |
546 | buffer. | |
547 | ||
548 | Both of these variables are temporarily bound to @code{nil} during the | |
549 | time that either of these hooks is running. This means that if one of | |
550 | these functions changes the buffer, that change won't run these | |
551 | functions. If you do want hooks to be run recursively, write your hook | |
552 | functions to bind these variables back to their usual values. | |
553 | ||
554 | @item | |
555 | The hook @code{first-change-hook} is run using @code{run-hooks} whenever | |
556 | a buffer is changed that was previously in the unmodified state. | |
557 | ||
558 | @item | |
559 | The second argument to @code{insert-abbrev-table-description} is | |
560 | now optional. | |
561 | @end itemize | |
562 | ||
563 | @section Text Properties | |
564 | ||
565 | Each character in a buffer or a string can have a @dfn{text property | |
566 | list}, much like the property list of a symbol. The properties belong | |
567 | to a particular character at a particular place, such as, the letter | |
568 | @samp{T} at the beginning of this sentence. Each property has a name, | |
569 | which is usually a symbol, and an associated value, which can be any | |
570 | Lisp object---just as for properties of symbols (@pxref{Property Lists}). | |
571 | ||
572 | You can use the property @code{face-code} to control the font and | |
573 | color of text. That is the only property name which currently has a | |
574 | special meaning, but you can create properties of any name and examine | |
575 | them later for your own purposes. | |
576 | ||
577 | Copying text between strings and buffers preserves the properties | |
578 | along with the characters; this includes such diverse functions as | |
579 | @code{substring}, @code{insert}, and @code{buffer-substring}. | |
580 | ||
581 | Since text properties are considered part of the buffer contents, | |
582 | changing properties in a buffer ``modifies'' the buffer, and you can | |
583 | also undo such changes. | |
584 | ||
585 | Strings with text properties have a special printed representation | |
586 | which describes all the properties. This representation is also the | |
587 | read syntax for such a string. It looks like this: | |
588 | ||
589 | @example | |
590 | #("@var{characters}" @var{property-data}...) | |
591 | @end example | |
592 | ||
593 | @noindent | |
594 | where @var{property-data} is zero or more elements in groups of three as | |
595 | follows: | |
596 | ||
597 | @example | |
598 | @var{beg} @var{end} @var{plist} | |
599 | @end example | |
600 | ||
601 | @noindent | |
602 | The elements @var{beg} and @var{end} are integers, and together specify | |
603 | a portion of the string; @var{plist} is the property list for that | |
604 | portion. | |
605 | ||
606 | @subsection Examining Text Properties | |
607 | ||
608 | The simplest way to examine text properties is to ask for the value of | |
609 | a particular property of a particular character. For that, use | |
610 | @code{get-text-property}. Use @code{text-properties-at} to get the | |
611 | entire property list of a character. @xref{Property Search}, for | |
612 | functions to examine the properties of a number of characters at once. | |
613 | ||
614 | @code{(get-text-property @var{pos} @var{prop} @var{object})} returns the | |
615 | @var{prop} property of the character after @var{pos} in @var{object} (a | |
616 | buffer or string). The argument @var{object} is optional and defaults | |
617 | to the current buffer. | |
618 | ||
619 | @code{(text-properties-at @var{pos} @var{object})} returns the entire | |
620 | property list of the character after @var{pos} in the string or buffer | |
621 | @var{object} (which defaults to the current buffer). | |
622 | ||
623 | @subsection Changing Text Properties | |
624 | ||
625 | There are three primitives for changing properties of a specified | |
626 | range of text: | |
627 | ||
628 | @table @code | |
629 | @item add-text-properties | |
630 | This function puts on specified properties, leaving other existing | |
631 | properties unaltered. | |
632 | ||
633 | @item put-text-property | |
634 | This function puts on a single specified property, leaving others | |
635 | unaltered. | |
636 | ||
637 | @item remove-text-properties | |
638 | This function removes specified properties, leaving other | |
639 | properties unaltered. | |
640 | ||
641 | @item set-text-properties | |
642 | This function replaces the entire property list, leaving no vessage of | |
643 | the properties that that text used to have. | |
644 | @end table | |
645 | ||
646 | All these functions take four arguments: @var{start}, @var{end}, | |
647 | @var{props}, and @var{object}. The last argument is optional and | |
648 | defaults to the current buffer. The argument @var{props} has the form | |
649 | of a property list. | |
650 | ||
651 | @subsection Property Search Functions | |
652 | ||
653 | In typical use of text properties, most of the time several or many | |
654 | consecutive characters have the same value for a property. Rather than | |
655 | writing your programs to examine characters one by one, it is much | |
656 | faster to process chunks of text that have the same property value. | |
657 | ||
658 | The functions @code{next-property-change} and | |
659 | @code{previous-property-change} scan forward or backward from position | |
660 | @var{pos} in @var{object}, looking for a change in any property between | |
661 | two characters scanned. They returns the position between those two | |
662 | characters, or @code{nil} if no change is found. | |
663 | ||
664 | The functions @code{next-single-property-change} and | |
665 | @code{previous-single-property-change} are similar except that you | |
666 | specify a particular property and they look for changes in the value of | |
667 | that property only. The property is the second argument, and | |
668 | @var{object} is third. | |
669 | ||
670 | @subsection Special Properties | |
671 | ||
672 | If a character has a @code{category} property, we call it the | |
673 | @dfn{category} of the character. It should be a symbol. The properties | |
674 | of the symbol serve as defaults for the properties of the character. | |
675 | ||
676 | You can use the property @code{face-code} to control the font and | |
677 | color of text. That is the only property name which currently has a | |
678 | special meaning, but you can create properties of any name and examine | |
679 | them later for your own purposes. | |
680 | about face codes. | |
681 | ||
682 | You can specify a different keymap for a portion of the text by means | |
683 | of a @code{local-map} property. The property's value, for the character | |
684 | after point, replaces the buffer's local map. | |
685 | ||
686 | If a character has the property @code{read-only}, then modifying that | |
687 | character is not allowed. Any command that would do so gets an error. | |
688 | ||
689 | If a character has the property @code{modification-hooks}, then its | |
690 | value should be a list of functions; modifying that character calls all | |
691 | of those functions. Each function receives two arguments: the beginning | |
692 | and end of the part of the buffer being modified. Note that if a | |
693 | particular modification hook function appears on several characters | |
694 | being modified by a single primitive, you can't predict how many times | |
695 | the function will be called. | |
696 | ||
697 | Insertion of text does not, strictly speaking, change any existing | |
698 | character, so there is a special rule for insertion. It compares the | |
699 | @code{read-only} properties of the two surrounding characters; if they | |
700 | are @code{eq}, then the insertion is not allowed. Assuming insertion is | |
701 | allowed, it then gets the @code{modification-hooks} properties of those | |
702 | characters and calls all the functions in each of them. (If a function | |
703 | appears on both characters, it may be called once or twice.) | |
704 | ||
705 | The special properties @code{point-entered} and @code{point-left} | |
706 | record hook functions that report motion of point. Each time point | |
707 | moves, Emacs compares these two property values: | |
708 | ||
709 | @itemize @bullet | |
710 | @item | |
711 | the @code{point-left} property of the character after the old location, | |
712 | and | |
713 | @item | |
714 | the @code{point-entered} property of the character after the new | |
715 | location. | |
716 | @end itemize | |
717 | ||
718 | @noindent | |
719 | If these two values differ, each of them is called (if not @code{nil}) | |
720 | with two arguments: the old value of point, and the new one. | |
721 | ||
722 | The same comparison is made for the characters before the old and new | |
723 | locations. The result may be to execute two @code{point-left} functions | |
724 | (which may be the same function) and/or two @code{point-entered} | |
725 | functions (which may be the same function). The @code{point-left} | |
726 | functions are always called before the @code{point-entered} functions. | |
727 | ||
728 | A primitive function may examine characters at various positions | |
729 | without moving point to those positions. Only an actual change in the | |
730 | value of point runs these hook functions. | |
731 | ||
732 | @section New Features for Files | |
733 | ||
734 | @itemize @bullet | |
735 | @item | |
736 | The new function @code{file-accessible-directory-p} tells you whether | |
737 | you can open files in a particular directory. Specify as an argument | |
738 | either a directory name or a file name which names a directory file. | |
739 | The function returns @code{t} if you can open existing files in that | |
740 | directory. | |
741 | ||
742 | @item | |
743 | The new function @code{file-executable-p} returns @code{t} if its | |
744 | argument is the name of a file you have permission to execute. | |
745 | ||
746 | @item | |
747 | The function @code{file-truename} returns the ``true name'' of a | |
748 | specified file. This is the name that you get by following symbolic | |
749 | links until none remain. The argument must be an absolute file name. | |
750 | ||
751 | @item | |
752 | New functions @code{make-directory} and @code{delete-directory} create and | |
753 | delete directories. They both take one argument, which is the name of | |
754 | the directory as a file. | |
755 | ||
756 | @item | |
757 | The function @code{read-file-name} now takes an additional argument | |
758 | which specifies an initial file name. If you specify this argument, | |
759 | @code{read-file-name} inserts it along with the directory name. It puts | |
760 | the cursor between the directory and the initial file name. | |
761 | ||
762 | The user can then use the initial file name unchanged, modify it, or | |
763 | simply kill it with @kbd{C-k}. | |
764 | ||
765 | If the variable @code{insert-default-directory} is @code{nil}, then the | |
766 | default directory is not inserted, and the new argument is ignored. | |
767 | ||
768 | @item | |
769 | The function @code{file-relative-name} does the inverse of | |
770 | expansion---it tries to return a relative name which is equivalent to | |
771 | @var{filename} when interpreted relative to @var{directory}. (If such a | |
772 | relative name would be longer than the absolute name, it returns the | |
773 | absolute name instead.) | |
774 | ||
775 | @item | |
776 | The function @code{file-newest-backup} returns the name of the most | |
777 | recent backup file for @var{filename}, or @code{nil} that file has no | |
778 | backup files. | |
779 | ||
780 | @item | |
781 | The list returned by @code{file-attributes} now has 12 elements. The | |
782 | 12th element is the file system number of the file system that the file | |
783 | is in. This element together with the file's inode number, which is the | |
784 | 11th element, give enough information to distinguish any two files on | |
785 | the system---no two files can have the same values for both of these | |
786 | numbers. | |
787 | ||
788 | @item | |
789 | The new function @code{set-visited-file-modtime} updates the current | |
790 | buffer's recorded modification time from the visited file's time. | |
791 | ||
792 | This is useful if the buffer was not read from the file normally, or | |
793 | if the file itself has been changed for some known benign reason. | |
794 | ||
795 | If you give the function an argument, that argument specifies the new | |
796 | value for the recorded modification time. The argument should be a list | |
797 | of the form @code{(@var{high} . @var{low})} or @code{(@var{high} | |
798 | @var{low})} containing two integers, each of which holds 16 bits of the | |
799 | time. (This is the same format that @code[file-attributes} uses to | |
800 | return time values.) | |
801 | ||
802 | The new function @code{visited-file-modtime} returns the recorded last | |
803 | modification time, in that same format. | |
804 | ||
805 | @item | |
806 | The function @code{directory-files} now takes an optional fourth | |
807 | argument which, if non-@code{nil}, inhibits sorting the file names. | |
808 | Use this if you want the utmost possible speed and don't care what order | |
809 | the files are processed in. | |
810 | ||
811 | If the order of processing is at all visible to the user, then the user | |
812 | will probably be happier if you do sort the names. | |
813 | ||
814 | @item | |
815 | The variable @code{directory-abbrev-alist} contains an alist of | |
816 | abbreviations to use for file directories. Each element has the form | |
817 | @code{(@var{from} . @var{to})}, and says to replace @var{from} with | |
818 | @var{to} when it appears in a directory name. This replacement is done | |
819 | when setting up the default directory of a newly visited file. The | |
820 | @var{from} string is actually a regular expression; it should always | |
821 | start with @samp{^}. | |
822 | ||
823 | You can set this variable in @file{site-init.el} to describe the | |
824 | abbreviations appropriate for your site. | |
825 | ||
826 | @item | |
827 | The function @code{abbreviate-file-name} applies abbreviations from | |
828 | @code{directory-abbrev-alist} to its argument, and substitutes @samp{~} | |
829 | for the user's home directory. | |
830 | ||
831 | Abbreviated directory names are useful for directories that are normally | |
832 | accessed through symbolic links. If you think of the link's name as | |
833 | ``the name'' of the directory, you can define it as an abbreviation for | |
834 | the directory's official name; then ordinarily Emacs will call that | |
835 | directory by the link name you normally use. | |
836 | ||
837 | @item | |
838 | @code{write-region} can write a given string instead of text from the | |
839 | buffer. Use the string as the first argument (in place of the | |
840 | starting character position). | |
841 | ||
842 | You can supply a second file name as the fifth argument (@var{visit}). | |
843 | Use this to write the data to one file (the first argument, | |
844 | @var{filename}) while nominally visiting a different file (the fifth | |
845 | argument, @var{visit}). The argument @var{visit} is used in the echo | |
846 | area message and also for file locking; @var{visit} is stored in | |
847 | @code{buffer-file-name}. | |
848 | ||
849 | @item | |
850 | The value of @code{write-file-hooks} does not change when you switch to | |
851 | a new major mode. The intention is that these hooks have to do with | |
852 | where the file came from, and not with what it contains. | |
853 | ||
854 | @item | |
855 | There is a new hook variable for saving files: | |
856 | @code{write-contents-hooks}. It works just like @code{write-file-hooks} | |
857 | except that switching to a new major mode clears it back to @code{nil}. | |
858 | Major modes should use this hook variable rather than | |
859 | @code{write-file-hooks}. | |
860 | ||
861 | @item | |
862 | The hook @code{after-save-hook} runs just after a buffer has been saved | |
863 | in its visited file. | |
864 | ||
865 | @item | |
866 | The new function @code{set-default-file-modes} sets the file protection | |
867 | for new files created with Emacs. The argument must be an integer. (It | |
868 | would be better to permit symbolic arguments like the @code{chmod} | |
869 | program, but that would take more work than this function merits.) | |
870 | ||
871 | Use the new function @code{default-file-modes} to read the current | |
872 | default file mode. | |
873 | ||
874 | @item | |
875 | Call the new function @code{unix-sync} to force all pending disk output | |
876 | to happen as soon as possible. | |
877 | @end itemize | |
878 | ||
879 | @section Making Certain File Names ``Magic'' | |
880 | ||
881 | You can implement special handling for a class of file names. You must | |
882 | supply a regular expression to define the class of names (all those | |
883 | which match the regular expression), plus a handler that implements all | |
884 | the primitive Emacs file operations for file names that do match. | |
885 | ||
886 | The value of @code{file-name-handler-alist} is a list of handlers, | |
887 | together with regular expressions that decide when to apply each | |
888 | handler. Each element has the form @code{(@var{regexp} | |
889 | . @var{handler})}. If a file name matches @var{regexp}, then all work | |
890 | on that file is done by calling @var{handler}. | |
891 | ||
892 | All the Emacs primitives for file access and file name transformation | |
893 | check the given file name against @code{file-name-handler-alist}, and | |
894 | call @var{handler} to do the work if appropriate. The first argument | |
895 | given to @var{handler} is the name of the primitive; the remaining | |
896 | arguments are the arguments that were passed to that primitive. (The | |
897 | first of these arguments is typically the file name itself.) For | |
898 | example, if you do this: | |
899 | ||
900 | @example | |
901 | (file-exists-p @var{filename}) | |
902 | @end example | |
903 | ||
904 | @noindent | |
905 | and @var{filename} has handler @var{handler}, then @var{handler} is | |
906 | called like this: | |
907 | ||
908 | @example | |
909 | (funcall @var{handler} 'file-exists-p @var{filename}) | |
910 | @end example | |
911 | ||
912 | Here are the primitives that you can handle in this way: | |
913 | ||
914 | @quotation | |
915 | @code{add-name-to-file}, @code{copy-file}, @code{delete-directory}, | |
916 | @code{delete-file}, @code{directory-file-name}, @code{directory-files}, | |
917 | @code{dired-compress-file}, @code{dired-uncache}, | |
918 | @code{expand-file-name}, @code{file-accessible-directory-p}, | |
919 | @code{file-attributes}, @code{file-directory-p}, | |
920 | @code{file-executable-p}, @code{file-exists-p}, @code{file-local-copy}, | |
921 | @code{file-modes}, @code{file-name-all-completions}, | |
922 | @code{file-name-as-directory}, @code{file-name-completion}, | |
923 | @code{file-name-directory}, @code{file-name-nondirectory}, | |
924 | @code{file-name-sans-versions}, @code{file-newer-than-file-p}, | |
925 | @code{file-readable-p}, @code{file-symlink-p}, @code{file-writable-p}, | |
926 | @code{insert-directory}, @code{insert-file-contents}, | |
927 | @code{make-directory}, @code{make-symbolic-link}, @code{rename-file}, | |
928 | @code{set-file-modes}, @code{verify-visited-file-modtime}, | |
929 | @code{write-region}. | |
930 | @end quotation | |
931 | ||
932 | The handler function must handle all of the above operations, and | |
933 | possibly others to be added in the future. Therefore, it should always | |
934 | reinvoke the ordinary Lisp primitive when it receives an operation it | |
935 | does not recognize. Here's one way to do this: | |
936 | ||
937 | @smallexample | |
938 | (defun my-file-handler (primitive &rest args) | |
939 | ;; @r{First check for the specific operations} | |
940 | ;; @r{that we have special handling for.} | |
941 | (cond ((eq operation 'insert-file-contents) @dots{}) | |
942 | ((eq operation 'write-region) @dots{}) | |
943 | @dots{} | |
944 | ;; @r{Handle any operation we don't know about.} | |
945 | (t (let (file-name-handler-alist) | |
946 | (apply operation args))))) | |
947 | @end smallexample | |
948 | ||
949 | The function @code{file-local-copy} copies file @var{filename} to the | |
950 | local site, if it isn't there already. If @var{filename} specifies a | |
951 | ``magic'' file name which programs outside Emacs cannot directly read or | |
952 | write, this copies the contents to an ordinary file and returns that | |
953 | file's name. | |
954 | ||
955 | If @var{filename} is an ordinary file name, not magic, then this function | |
956 | does nothing and returns @code{nil}. | |
957 | ||
958 | The function @code{unhandled-file-name-directory} is used to get a | |
959 | non-magic directory name from an arbitrary file name. It uses the | |
960 | directory part of the specified file name if that is not magic. | |
961 | Otherwise, it asks the file name's handler what to do. | |
962 | ||
963 | @section Frames | |
964 | @cindex frame | |
965 | ||
966 | Emacs now supports multiple X windows via a new data type known as a | |
967 | @dfn{frame}. | |
968 | ||
969 | A frame is a rectangle on the screen that contains one or more Emacs | |
970 | windows. Subdividing a frame works just like subdividing the screen in | |
971 | earlier versions of Emacs. | |
972 | ||
973 | @cindex terminal frame | |
974 | There are two kinds of frames: terminal frames and X window frames. | |
975 | Emacs creates one terminal frame when it starts up with no X display; it | |
976 | uses Termcap or Terminfo to display using characters. There is no way | |
977 | to create another terminal frame after startup. If Emacs has an X | |
978 | display, it does not make a terminal frame, and there is none. | |
979 | ||
980 | @cindex X window frame | |
981 | When you are using X windows, Emacs starts out with a single X window | |
982 | frame. You can create any number of X window frames using | |
983 | @code{make-frame}. | |
984 | ||
985 | Use the predicate @code{framep} to determine whether a given Lisp object | |
986 | is a frame. | |
987 | ||
988 | The function @code{redraw-frame} redisplays the entire contents of a | |
989 | given frame. | |
990 | ||
991 | @subsection Creating and Deleting Frames | |
992 | ||
993 | Use @code{make-frame} to create a new frame (supported under X Windows | |
994 | only). This is the only primitive for creating frames. | |
995 | ||
996 | @code{make-frame} takes just one argument, which is an alist | |
997 | specifying frame parameters. Any parameters not mentioned in the | |
998 | argument alist default based on the value of @code{default-frame-alist}; | |
999 | parameters not specified there default from the standard X defaults file | |
1000 | and X resources. | |
1001 | ||
1002 | When you invoke Emacs, if you specify arguments for window appearance | |
1003 | and so forth, these go into @code{default-frame-alist} and that is how | |
1004 | they have their effect. | |
1005 | ||
1006 | You can specify the parameters for the initial startup X window frame by | |
1007 | setting @code{initial-frame-alist} in your @file{.emacs} file. If these | |
1008 | parameters specify a separate minibuffer-only frame, and you have not | |
1009 | created one, Emacs creates one for you, using the parameter values | |
1010 | specified in @code{minibuffer-frame-alist}. | |
1011 | ||
1012 | You can specify the size and position of a frame using the frame | |
1013 | parameters @code{left}, @code{top}, @code{height} and @code{width}. You | |
1014 | must specify either both size parameters or neither. You must specify | |
1015 | either both position parameters or neither. The geometry parameters | |
1016 | that you don't specify are chosen by the window manager in its usual | |
1017 | fashion. | |
1018 | ||
1019 | The function @code{x-parse-geometry} converts a standard X windows | |
1020 | geometry string to an alist which you can use as part of the argument to | |
1021 | @code{make-frame}. | |
1022 | ||
1023 | Use the function @code{delete-frame} to eliminate a frame. Frames are | |
1024 | like buffers where deletion is concerned; a frame actually continues to | |
1025 | exist as a Lisp object until it is deleted @emph{and} there are no | |
1026 | references to it, but once it is deleted, it has no further effect on | |
1027 | the screen. | |
1028 | ||
1029 | The function @code{frame-live-p} returns non-@code{nil} if the argument | |
1030 | (a frame) has not been deleted. | |
1031 | ||
1032 | @subsection Finding All Frames | |
1033 | ||
1034 | The function @code{frame-list} returns a list of all the frames that have | |
1035 | not been deleted. It is analogous to @code{buffer-list}. The list that | |
1036 | you get is newly created, so modifying the list doesn't have any effect | |
1037 | on the internals of Emacs. The function @code{visible-frame-list} returns | |
1038 | the list of just the frames that are visible. | |
1039 | ||
1040 | @code{next-frame} lets you cycle conveniently through all the frames from an | |
1041 | arbitrary starting point. Its first argument is a frame. Its second | |
1042 | argument @var{minibuf} says what to do about minibuffers: | |
1043 | ||
1044 | @table @asis | |
1045 | @item @code{nil} | |
1046 | Exclude minibuffer-only frames. | |
1047 | @item a window | |
1048 | Consider only the frames using that particular window as their | |
1049 | minibuffer. | |
1050 | @item anything else | |
1051 | Consider all frames. | |
1052 | @end table | |
1053 | ||
1054 | @subsection Frames and Windows | |
1055 | ||
1056 | All the non-minibuffer windows in a frame are arranged in a tree of | |
1057 | subdivisions; the root of this tree is available via the function | |
1058 | @code{frame-root-window}. Each window is part of one and only one | |
1059 | frame; you can get the frame with @code{window-frame}. | |
1060 | ||
1061 | At any time, exactly one window on any frame is @dfn{selected within the | |
1062 | frame}. You can get the frame's current selected window with | |
1063 | @code{frame-selected-window}. The significance of this designation is | |
1064 | that selecting the frame selects for Emacs as a whole the window | |
1065 | currently selected within that frame. | |
1066 | ||
1067 | Conversely, selecting a window for Emacs with @code{select-window} also | |
1068 | makes that window selected within its frame. | |
1069 | ||
1070 | @subsection Frame Visibility | |
1071 | ||
1072 | A frame may be @dfn{visible}, @dfn{invisible}, or @dfn{iconified}. If | |
1073 | it is invisible, it doesn't show in the screen, not even as an icon. | |
1074 | You can set the visibility status of a frame with | |
1075 | @code{make-frame-visible}, @code{make-frame-invisible}, and | |
1076 | @code{iconify-frame}. You can examine the visibility status with | |
1077 | @code{frame-visible-p}---it returns @code{t} for a visible frame, | |
1078 | @code{nil} for an invisible frame, and @code{icon} for an iconified | |
1079 | frame. | |
1080 | ||
1081 | @subsection Selected Frame | |
1082 | ||
1083 | At any time, one frame in Emacs is the @dfn{selected frame}. The selected | |
1084 | window always resides on the selected frame. | |
1085 | ||
1086 | @defun selected-frame | |
1087 | This function returns the selected frame. | |
1088 | @end defun | |
1089 | ||
1090 | The X server normally directs keyboard input to the X window that the | |
1091 | mouse is in. Some window managers use mouse clicks or keyboard events | |
1092 | to @dfn{shift the focus} to various X windows, overriding the normal | |
1093 | behavior of the server. | |
1094 | ||
1095 | Lisp programs can switch frames ``temporarily'' by calling the function | |
1096 | @code{select-frame}. This does not override the window manager; rather, | |
1097 | it escapes from the window manager's control until that control is | |
1098 | somehow reasserted. The function takes one argument, a frame, and | |
1099 | selects that frame. The selection lasts until the next time the user | |
1100 | does something to select a different frame, or until the next time this | |
1101 | function is called. | |
1102 | ||
1103 | Emacs cooperates with the X server and the window managers by arranging | |
1104 | to select frames according to what the server and window manager ask | |
1105 | for. It does so by generating a special kind of input event, called a | |
1106 | @dfn{focus} event. The command loop handles a focus event by calling | |
1107 | @code{internal-select-frame}. @xref{Focus Events}. | |
1108 | ||
1109 | @subsection Frame Size and Position | |
1110 | ||
1111 | The new functions @code{frame-height} and @code{frame-width} return the | |
1112 | height and width of a specified frame (or of the selected frame), | |
1113 | measured in characters. | |
1114 | ||
1115 | The new functions @code{frame-pixel-height} and @code{frame-pixel-width} | |
1116 | return the height and width of a specified frame (or of the selected | |
1117 | frame), measured in pixels. | |
1118 | ||
1119 | The new functions @code{frame-char-height} and @code{frame-char-width} | |
1120 | return the height and width of a character in a specified frame (or in | |
1121 | the selected frame), measured in pixels. | |
1122 | ||
1123 | @code{set-frame-size} sets the size of a frame, measured in characters; | |
1124 | its arguments are @var{frame}, @var{cols} and @var{rows}. To set the | |
1125 | size with values measured in pixels, you can use | |
1126 | @code{modify-frame-parameters}. | |
1127 | ||
1128 | The function @code{set-frame-position} sets the position of the top left | |
1129 | corner of a frame. Its arguments are @var{frame}, @var{left} and | |
1130 | @var{top}. | |
1131 | ||
1132 | @ignore | |
1133 | New functions @code{set-frame-height} and @code{set-frame-width} set the | |
1134 | size of a specified frame. The frame is the first argument; the size is | |
1135 | the second. | |
1136 | @end ignore | |
1137 | ||
1138 | @subsection Frame Parameters | |
1139 | ||
1140 | A frame has many parameters that affect how it displays. Use the | |
1141 | function @code{frame-parameters} to get an alist of all the parameters | |
1142 | of a given frame. To alter parameters, use | |
1143 | @code{modify-frame-parameters}, which takes two arguments: the frame to | |
1144 | modify, and an alist of parameters to change and their new values. Each | |
1145 | element of @var{alist} has the form @code{(@var{parm} . @var{value})}, | |
1146 | where @var{parm} is a symbol. Parameters that aren't meaningful are | |
1147 | ignored. If you don't mention a parameter in @var{alist}, its value | |
1148 | doesn't change. | |
1149 | ||
1150 | Just what parameters a frame has depends on what display mechanism it | |
1151 | uses. Here is a table of the parameters of an X | |
1152 | window frame: | |
1153 | ||
1154 | @table @code | |
1155 | @item name | |
1156 | The name of the frame. | |
1157 | ||
1158 | @item left | |
1159 | The screen position of the left edge. | |
1160 | ||
1161 | @item top | |
1162 | The screen position of the top edge. | |
1163 | ||
1164 | @item height | |
1165 | The height of the frame contents, in pixels. | |
1166 | ||
1167 | @item width | |
1168 | The width of the frame contents, in pixels. | |
1169 | ||
1170 | @item window-id | |
1171 | The number of the X window for the frame. | |
1172 | ||
1173 | @item minibuffer | |
1174 | Whether this frame has its own minibuffer. | |
1175 | @code{t} means yes, @code{none} means no, | |
1176 | @code{only} means this frame is just a minibuffer, | |
1177 | a minibuffer window (in some other frame) | |
1178 | means the new frame uses that minibuffer. | |
1179 | ||
1180 | @item font | |
1181 | The name of the font for the text. | |
1182 | ||
1183 | @item foreground-color | |
1184 | The color to use for the inside of a character. | |
1185 | Use strings to designate colors; | |
1186 | X windows defines the meaningful color names. | |
1187 | ||
1188 | @item background-color | |
1189 | The color to use for the background of text. | |
1190 | ||
1191 | @item mouse-color | |
1192 | The color for the mouse cursor. | |
1193 | ||
1194 | @item cursor-color | |
1195 | The color for the cursor that shows point. | |
1196 | ||
1197 | @item border-color | |
1198 | The color for the border of the frame. | |
1199 | ||
1200 | @item cursor-type | |
1201 | The way to display the cursor. There are two legitimate values: | |
1202 | @code{bar} and @code{box}. The value @code{bar} specifies a vertical | |
1203 | bar between characters as the cursor. The value @code{box} specifies an | |
1204 | ordinary black box overlaying the character after point; that is the | |
1205 | default. | |
1206 | ||
1207 | @item icon-type | |
1208 | Non-@code{nil} for a bitmap icon, @code{nil} for a text icon. | |
1209 | ||
1210 | @item border-width | |
1211 | The width in pixels of the window border. | |
1212 | ||
1213 | @item internal-border-width | |
1214 | The distance in pixels between text and border. | |
1215 | ||
1216 | @item auto-raise | |
1217 | Non-@code{nil} means selecting the frame raises it. | |
1218 | ||
1219 | @item auto-lower | |
1220 | Non-@code{nil} means deselecting the frame lowers it. | |
1221 | ||
1222 | @item vertical-scrollbar | |
1223 | Non-@code{nil} gives the frame a scroll bar | |
1224 | for vertical scrolling. | |
1225 | ||
1226 | @item horizontal-scrollbar | |
1227 | Non-@code{nil} gives the frame a scroll bar | |
1228 | for horizontal scrolling. | |
1229 | @end table | |
1230 | ||
1231 | @subsection Minibufferless Frames | |
1232 | ||
1233 | Normally, each frame has its own minibuffer window at the bottom, which | |
1234 | is used whenever that frame is selected. However, you can also create | |
1235 | frames with no minibuffers. These frames must use the minibuffer window | |
1236 | of some other frame. | |
1237 | ||
1238 | The variable @code{default-minibuffer-frame} specifies where to find a | |
1239 | minibuffer for frames created without minibuffers of their own. Its | |
1240 | value should be a frame which does have a minibuffer. | |
1241 | ||
1242 | You can also specify a minibuffer window explicitly when you create a | |
1243 | frame; then @code{default-minibuffer-frame} is not used. | |
1244 | ||
1245 | @section X Windows Features | |
1246 | ||
1247 | @itemize @bullet | |
1248 | @item | |
1249 | The new functions @code{mouse-position} and @code{set-mouse-position} give | |
1250 | access to the current position of the mouse. | |
1251 | ||
1252 | @code{mouse-position} returns a description of the position of the mouse. | |
1253 | The value looks like @code{(@var{frame} @var{x} . @var{y})}, where @var{x} | |
1254 | and @var{y} are measured in pixels relative to the top left corner of | |
1255 | the inside of @var{frame}. | |
1256 | ||
1257 | @code{set-mouse-position} takes three arguments, @var{frame}, @var{x} | |
1258 | and @var{y}, and warps the mouse cursor to that location on the screen. | |
1259 | ||
1260 | @item | |
1261 | @code{track-mouse} is a new special form for tracking mouse motion. | |
1262 | Use it in definitions of mouse clicks that want pay to attention to | |
1263 | the motion of the mouse, not just where the buttons are pressed and | |
1264 | released. Here is how to use it: | |
1265 | ||
1266 | @example | |
1267 | (track-mouse @var{body}@dots{}) | |
1268 | @end example | |
1269 | ||
1270 | While @var{body} executes, mouse motion generates input events just as mouse | |
1271 | clicks do. @var{body} can read them with @code{read-event} or | |
1272 | @code{read-key-sequence}. | |
1273 | ||
1274 | @code{track-mouse} returns the value of the last form in @var{body}. | |
1275 | ||
1276 | The format of these events is described under ``New features for key | |
1277 | bindings and input.'' | |
1278 | @c ??? | |
1279 | ||
1280 | @item | |
1281 | @code{x-set-selection} sets a ``selection'' in the X Windows server. | |
1282 | It takes two arguments: a selection type @var{type}, and the value to | |
1283 | assign to it, @var{data}. If @var{data} is @code{nil}, it means to | |
1284 | clear out the selection. Otherwise, @var{data} may be a string, a | |
1285 | symbol, an integer (or a cons of two integers or list of two integers), | |
1286 | or a cons of two markers pointing to the same buffer. In the last case, | |
1287 | the selection is considered to be the text between the markers. The | |
1288 | data may also be a vector of valid non-vector selection values. | |
1289 | ||
1290 | Each possible @var{type} has its own selection value, which changes | |
1291 | independently. The usual values of @var{type} are @code{PRIMARY} and | |
1292 | @code{SECONDARY}; these are symbols with upper-case names, in accord | |
1293 | with X Windows conventions. The default is @code{PRIMARY}. | |
1294 | ||
1295 | To get the value of the selection, call @code{x-get-selection}. This | |
1296 | function accesses selections set up by Emacs and those set up by other X | |
1297 | clients. It takes two optional arguments, @var{type} and | |
1298 | @var{data-type}. The default for @var{type} is @code{PRIMARY}. | |
1299 | ||
1300 | The @var{data-type} argument specifies the form of data conversion to | |
1301 | use; meaningful values include @code{TEXT}, @code{STRING}, | |
1302 | @code{TARGETS}, @code{LENGTH}, @code{DELETE}, @code{FILE_NAME}, | |
1303 | @code{CHARACTER_POSITION}, @code{LINE_NUMBER}, @code{COLUMN_NUMBER}, | |
1304 | @code{OWNER_OS}, @code{HOST_NAME}, @code{USER}, @code{CLASS}, | |
1305 | @code{NAME}, @code{ATOM}, and @code{INTEGER}. (These are symbols with | |
1306 | upper-case names in accord with X Windows conventions.) | |
1307 | The default for @var{data-type} is @code{STRING}. | |
1308 | ||
1309 | @item | |
1310 | X Windows has a set of numbered @dfn{cut buffers} which can store text | |
1311 | or other data being moved between applications. Use | |
1312 | @code{x-get-cut-buffer} to get the contents of a cut buffer; specify the | |
1313 | cut buffer number as argument. Use @code{x-set-cut-buffer} with | |
1314 | argument @var{string} to store a new string into the first cut buffer | |
1315 | (moving the other values down through the series of cut buffers, | |
1316 | kill-ring-style). | |
1317 | ||
1318 | Cut buffers are considered obsolete in X Windows, but Emacs supports | |
1319 | them for the sake of X clients that still use them. | |
1320 | ||
1321 | @item | |
1322 | You can close the connection with the X Windows server with | |
1323 | the function @code{x-close-current-connection}. This takes no arguments. | |
1324 | ||
1325 | Then you can connect to a different X Windows server with | |
1326 | @code{x-open-connection}. The first argument, @var{display}, is the | |
1327 | name of the display to connect to. | |
1328 | ||
1329 | The optional second argument @var{xrm-string} is a string of resource | |
1330 | names and values, in the same format used in the @file{.Xresources} | |
1331 | file. The values you specify override the resource values recorded in | |
1332 | the X Windows server itself. Here's an example of what this string | |
1333 | might look like: | |
1334 | ||
1335 | @example | |
1336 | "*BorderWidth: 3\n*InternalBorder: 2\n" | |
1337 | @end example | |
1338 | ||
1339 | @item | |
1340 | A series of new functions give you information about the X server and | |
1341 | the screen you are using. | |
1342 | ||
1343 | @table @code | |
1344 | @item x-display-screens | |
1345 | The number of screens associated with the current display. | |
1346 | ||
1347 | @item x-server-version | |
1348 | The version numbers of the X server in use. | |
1349 | ||
1350 | @item x-server-vendor | |
1351 | The vendor supporting the X server in use. | |
1352 | ||
1353 | @item x-display-pixel-height | |
1354 | The height of this X screen in pixels. | |
1355 | ||
1356 | @item x-display-mm-height | |
1357 | The height of this X screen in millimeters. | |
1358 | ||
1359 | @item x-display-pixel-width | |
1360 | The width of this X screen in pixels. | |
1361 | ||
1362 | @item x-display-mm-width | |
1363 | The width of this X screen in millimeters. | |
1364 | ||
1365 | @item x-display-backing-store | |
1366 | The backing store capability of this screen. Values can be the symbols | |
1367 | @code{always}, @code{when-mapped}, or @code{not-useful}. | |
1368 | ||
1369 | @item x-display-save-under | |
1370 | Non-@code{nil} if this X screen supports the SaveUnder feature. | |
1371 | ||
1372 | @item x-display-planes | |
1373 | The number of planes this display supports. | |
1374 | ||
1375 | @item x-display-visual-class | |
1376 | The visual class for this X screen. The value is one of the symbols | |
1377 | @code{static-gray}, @code{gray-scale}, @code{static-color}, | |
1378 | @code{pseudo-color}, @code{true-color}, and @code{direct-color}. | |
1379 | ||
1380 | @item x-display-color-p | |
1381 | @code{t} if the X screen in use is a color screen. | |
1382 | ||
1383 | @item x-display-color-cells | |
1384 | The number of color cells this X screen supports. | |
1385 | @end table | |
1386 | ||
1387 | There is also a variable @code{x-no-window-manager}, whose value is | |
1388 | @code{t} if no X window manager is in use. | |
1389 | ||
1390 | @item | |
1391 | The function @code{x-synchronize} enables or disables an X Windows | |
1392 | debugging mode: synchronous communication. It takes one argument, | |
1393 | non-@code{nil} to enable the mode and @code{nil} to disable. | |
1394 | ||
1395 | In synchronous mode, Emacs waits for a response to each X protocol | |
1396 | command before doing anything else. This means that errors are reported | |
1397 | right away, and you can directly find the erroneous command. | |
1398 | Synchronous mode is not the default because it is much slower. | |
1399 | ||
1400 | @item | |
1401 | The function @code{x-get-resource} retrieves a resource value from the X | |
1402 | Windows defaults database. Its three arguments are @var{attribute}, | |
1403 | @var{name} and @var{class}. It searches using a key of the form | |
1404 | @samp{@var{instance}.@var{attribute}}, with class @samp{Emacs}, where | |
1405 | @var{instance} is the name under which Emacs was invoked. | |
1406 | ||
1407 | The optional arguments @var{component} and @var{subclass} add to the key | |
1408 | and the class, respectively. You must specify both of them or neither. | |
1409 | If you specify them, the key is | |
1410 | @samp{@var{instance}.@var{component}.@var{attribute}}, and the class is | |
1411 | @samp{Emacs.@var{subclass}}. | |
1412 | ||
1413 | @item | |
1414 | @code{x-color-display-p} returns @code{t} if you are using an X Window | |
1415 | server with a color display, and @code{nil} otherwise. | |
1416 | ||
1417 | @c ??? Name being changed from x-defined-color. | |
1418 | @code{x-color-defined-p} takes as argument a string describing a color; it | |
1419 | returns @code{t} if the display supports that color. (If the color is | |
1420 | @code{"black"} or @code{"white"} then even black-and-white displays | |
1421 | support it.) | |
1422 | ||
1423 | @item | |
1424 | @code{x-popup-menu} has been generalized. It now accepts a keymap as | |
1425 | the @var{menu} argument. Then the menu items are the prompt strings of | |
1426 | individual key bindings, and the item values are the keys which have | |
1427 | those bindings. | |
1428 | ||
1429 | You can also supply a list of keymaps as the first argument; then each | |
1430 | keymap makes one menu pane (but keymaps that don't provide any menu | |
1431 | items don't appear in the menu at all). | |
1432 | ||
1433 | @code{x-popup-menu} also accepts a mouse button event as the | |
1434 | @var{position} argument. Then it displays the menu at the location at | |
1435 | which the event took place. This is convenient for mouse-invoked | |
1436 | commands that pop up menus. | |
1437 | ||
1438 | @ignore | |
1439 | @item | |
1440 | x-pointer-shape, x-nontext-pointer-shape, x-mode-pointer-shape. | |
1441 | @end ignore | |
1442 | ||
1443 | @item | |
1444 | You can use the function @code{x-rebind-key} to change the sequence | |
1445 | of characters generated by one of the keyboard keys. This works | |
1446 | only with X Windows. | |
1447 | ||
1448 | The first two arguments, @var{keycode} and @var{shift-mask}, should be | |
1449 | numbers representing the keyboard code and shift mask respectively. | |
1450 | They specify what key to change. | |
1451 | ||
1452 | The third argument, @var{newstring}, is the new definition of the key. | |
1453 | It is a sequence of characters that the key should produce as input. | |
1454 | ||
1455 | The shift mask value is a combination of bits according to this table: | |
1456 | ||
1457 | @table @asis | |
1458 | @item 8 | |
1459 | Control | |
1460 | @item 4 | |
1461 | Meta | |
1462 | @item 2 | |
1463 | Shift | |
1464 | @item 1 | |
1465 | Shift Lock | |
1466 | @end table | |
1467 | ||
1468 | If you specify @code{nil} for @var{shift-mask}, then the key specified | |
1469 | by @var{keycode} is redefined for all possible shift combinations. | |
1470 | ||
1471 | For the possible values of @var{keycode} and their meanings, see the | |
1472 | file @file{/usr/lib/Xkeymap.txt}. Keep in mind that the codes in that | |
1473 | file are in octal! | |
1474 | ||
1475 | @ignore @c Presumably this is already fixed | |
1476 | NOTE: due to an X bug, this function will not take effect unless the | |
1477 | user has a @file{~/.Xkeymap} file. (See the documentation for the | |
1478 | @code{keycomp} program.) This problem will be fixed in X version 11. | |
1479 | @end ignore | |
1480 | ||
1481 | The related function @code{x-rebind-keys} redefines a single keyboard | |
1482 | key, specifying the behavior for each of the 16 shift masks | |
1483 | independently. The first argument is @var{keycode}, as in | |
1484 | @code{x-rebind-key}. The second argument @var{strings} is a list of 16 | |
1485 | elements, one for each possible shift mask value; each element says how | |
1486 | to redefine the key @var{keycode} with the corresponding shift mask | |
1487 | value. If an element is a string, it is the new definition. If an | |
1488 | element is @code{nil}, the definition does not change for that shift | |
1489 | mask. | |
1490 | ||
1491 | @item | |
1492 | The function @code{x-geometry} parses a string specifying window size | |
1493 | and position in the usual fashion for X windows. It returns an alist | |
1494 | describing which parameters were specified, and the values that were | |
1495 | given for them. | |
1496 | ||
1497 | The elements of the alist look like @code{(@var{parameter} . | |
1498 | @var{value})}. The possible @var{parameter} values are @code{left}, | |
1499 | @code{top}, @code{width}, and @code{height}. | |
1500 | @end itemize | |
1501 | ||
1502 | @section New Window Features | |
1503 | ||
1504 | @itemize @bullet | |
1505 | @item | |
1506 | The new function @code{window-at} tells you which window contains a | |
1507 | given horizontal and vertical position on a specified frame. Call it | |
1508 | with three arguments, like this: | |
1509 | ||
1510 | @example | |
1511 | (window-at @var{x} @var{column} @var{frame}) | |
1512 | @end example | |
1513 | ||
1514 | The function returns the window which contains that cursor position in | |
1515 | the frame @var{frame}. If you omit @var{frame}, the selected frame is | |
1516 | used. | |
1517 | ||
1518 | @item | |
1519 | The function @code{coordinates-in-window-p} takes two arguments and | |
1520 | checks whether a particular frame position falls within a particular | |
1521 | window. | |
1522 | ||
1523 | @example | |
1524 | (coordinates-in-window-p @var{coordinates} @var{window}) | |
1525 | @end example | |
1526 | ||
1527 | The argument @var{coordinates} is a cons cell of this form: | |
1528 | ||
1529 | @example | |
1530 | (@var{x} . @var{y}) | |
1531 | @end example | |
1532 | ||
1533 | @noindent | |
1534 | The two coordinates are measured in characters, and count from the top | |
1535 | left corner of the screen or frame. | |
1536 | ||
1537 | The value of the function tells you what part of the window the position | |
1538 | is in. The possible values are: | |
1539 | ||
1540 | @table @code | |
1541 | @item (@var{relx} . @var{rely}) | |
1542 | The coordinates are inside @var{window}. The numbers @var{relx} and | |
1543 | @var{rely} are equivalent window-relative coordinates, counting from 0 | |
1544 | at the top left corner of the window. | |
1545 | ||
1546 | @item mode-line | |
1547 | The coordinates are in the mode line of @var{window}. | |
1548 | ||
1549 | @item vertical-split | |
1550 | The coordinates are in the vertical line between @var{window} and its | |
1551 | neighbor to the right. | |
1552 | ||
1553 | @item nil | |
1554 | The coordinates are not in any sense within @var{window}. | |
1555 | @end table | |
1556 | ||
1557 | You need not specify a frame when you call | |
1558 | @code{coordinates-in-window-p}, because it assumes you mean the frame | |
1559 | which window @var{window} is on. | |
1560 | ||
1561 | @item | |
1562 | The function @code{minibuffer-window} now accepts a frame as argument | |
1563 | and returns the minibuffer window used for that frame. If you don't | |
1564 | specify a frame, the currently selected frame is used. The minibuffer | |
1565 | window may be on the frame in question, but if that frame has no | |
1566 | minibuffer of its own, it uses the minibuffer window of some other | |
1567 | frame, and @code{minibuffer-window} returns that window. | |
1568 | ||
1569 | @item | |
1570 | Use @code{window-live-p} to test whether a window is still alive (that | |
1571 | is, not deleted). | |
1572 | ||
1573 | @item | |
1574 | Use @code{window-minibuffer-p} to determine whether a given window is a | |
1575 | minibuffer or not. It no longer works to do this by comparing the | |
1576 | window with the result of @code{(minibuffer-window)}, because there can | |
1577 | be more than one minibuffer window at a time (if you have multiple | |
1578 | frames). | |
1579 | ||
1580 | @item | |
1581 | If you set the variable @code{pop-up-frames} non-@code{nil}, then the | |
1582 | functions to show something ``in another window'' actually create a new | |
1583 | frame for the new window. Thus, you will tend to have a frame for each | |
1584 | window, and you can easily have a frame for each buffer. | |
1585 | ||
1586 | The value of the variable @code{pop-up-frame-function} controls how new | |
1587 | frames are made. The value should be a function which takes no | |
1588 | arguments and returns a frame. The default value is a function which | |
1589 | creates a frame using parameters from @code{pop-up-frame-alist}. | |
1590 | ||
1591 | @item | |
1592 | @code{display-buffer} is the basic primitive for finding a way to show a | |
1593 | buffer on the screen. You can customize its behavior by storing a | |
1594 | function in the variable @code{display-buffer-function}. If this | |
1595 | variable is non-@code{nil}, then @code{display-buffer} calls it to do | |
1596 | the work. Your function should accept two arguments, as follows: | |
1597 | ||
1598 | @table @var | |
1599 | @item buffer | |
1600 | The buffer to be displayed. | |
1601 | ||
1602 | @item flag | |
1603 | A flag which, if non-@code{nil}, means you should find another window to | |
1604 | display @var{buffer} in, even if it is already visible in the selected | |
1605 | window. | |
1606 | @end table | |
1607 | ||
1608 | The function you supply will be used by commands such as | |
1609 | @code{switch-to-buffer-other-window} and @code{find-file-other-window} | |
1610 | as well as for your own calls to @code{display-buffer}. | |
1611 | ||
1612 | @item | |
1613 | @code{delete-window} now gives all of the deleted window's screen space | |
1614 | to a single neighboring window. Likewise, @code{enlarge-window} takes | |
1615 | space from only one neighboring window until that window disappears; | |
1616 | only then does it take from another window. | |
1617 | ||
1618 | @item | |
1619 | @code{next-window} and @code{previous-window} accept another argument, | |
1620 | @var{all-frames}. | |
1621 | ||
1622 | These functions now take three optional arguments: @var{window}, | |
1623 | @var{minibuf} and @var{all-frames}. @var{window} is the window to start | |
1624 | from (@code{nil} means use the selected window). @var{minibuf} says | |
1625 | whether to include the minibuffer in the windows to cycle through: | |
1626 | @code{t} means yes, @code{nil} means yes if it is active, and anything | |
1627 | else means no. | |
1628 | ||
1629 | Normally, these functions cycle through all the windows in the | |
1630 | selected frame, plus the minibuffer used by the selected frame even if | |
1631 | it lies in some other frame. | |
1632 | ||
1633 | If @var{all-frames} is @code{t}, then these functions cycle through | |
1634 | all the windows in all the frames that currently exist. If | |
1635 | @var{all-frames} is neither @code{t} nor @code{nil}, then they limit | |
1636 | themselves strictly to the windows in the selected frame, excluding the | |
1637 | minibuffer in use if it lies in some other frame. | |
1638 | ||
1639 | @item | |
1640 | The functions @code{get-lru-window} and @code{get-largest-window} now | |
1641 | take an optional argument @var{all-frames}. If it is non-@code{nil}, | |
1642 | the functions consider all windows on all frames. Otherwise, they | |
1643 | consider just the windows on the selected frame. | |
1644 | ||
1645 | Likewise, @code{get-buffer-window} takes an optional second argument | |
1646 | @var{all-frames}. | |
1647 | ||
1648 | @item | |
1649 | The variable @code{other-window-scroll-buffer} specifies which buffer | |
1650 | @code{scroll-other-window} should scroll. | |
1651 | ||
1652 | @item | |
1653 | You can now mark a window as ``dedicated'' to its buffer. | |
1654 | Then Emacs will not try to use that window for any other buffer | |
1655 | unless you explicitly request it. | |
1656 | ||
1657 | Use the new function @code{set-window-dedicated-p} to set the dedication | |
1658 | flag of a window @var{window} to the value @var{flag}. If @var{flag} is | |
1659 | @code{t}, this makes the window dedicated. If @var{flag} is | |
1660 | @code{nil}, this makes the window non-dedicated. | |
1661 | ||
1662 | Use @code{window-dedicated-p} to examine the dedication flag of a | |
1663 | specified window. | |
1664 | ||
1665 | @item | |
1666 | The new function @code{walk-windows} cycles through all visible | |
1667 | windows, calling @code{proc} once for each window with the window as | |
1668 | its sole argument. | |
1669 | ||
1670 | The optional second argument @var{minibuf} says whether to include minibuffer | |
1671 | windows. A value of @code{t} means count the minibuffer window even if | |
1672 | not active. A value of @code{nil} means count it only if active. Any | |
1673 | other value means not to count the minibuffer even if it is active. | |
1674 | ||
1675 | If the optional third argument @var{all-frames} is @code{t}, that means | |
1676 | include all windows in all frames. If @var{all-frames} is @code{nil}, | |
1677 | it means to cycle within the selected frame, but include the minibuffer | |
1678 | window (if @var{minibuf} says so) that that frame uses, even if it is on | |
1679 | another frame. If @var{all-frames} is neither @code{nil} nor @code{t}, | |
1680 | @code{walk-windows} sticks strictly to the selected frame. | |
1681 | ||
1682 | @item | |
1683 | The function @code{window-end} is a counterpart to @code{window-start}: | |
1684 | it returns the buffer position of the end of the display in a given | |
1685 | window (or the selected window). | |
1686 | ||
1687 | @item | |
1688 | The function @code{window-configuration-p} returns non-@code{nil} when | |
1689 | given an object that is a window configuration (such as is returned by | |
1690 | @code{current-window-configuration}). | |
1691 | @end itemize | |
1692 | ||
1693 | @section Display Features | |
1694 | ||
1695 | @itemize @bullet | |
1696 | @item | |
1697 | @samp{%l} as a mode line item displays the current line number. | |
1698 | ||
1699 | If the buffer is longer than @code{line-number-display-limit} | |
1700 | characters, or if lines are too long in the viscinity of the current | |
1701 | displayed text, then line number display is inhibited to save time. | |
1702 | ||
1703 | The default contents of the mode line include the line number if | |
1704 | @code{line-number-mode} is non-@code{nil}. | |
1705 | ||
1706 | @item | |
1707 | @code{baud-rate} is now a variable rather than a function. This is so | |
1708 | you can set it to reflect the effective speed of your terminal, when the | |
1709 | system doesn't accurately know the speed. | |
1710 | ||
1711 | @item | |
1712 | You can now remove any echo area message and make the minibuffer | |
1713 | visible. To do this, call @code{message} with @code{nil} as the only | |
1714 | argument. This clears any existing message, and lets the current | |
1715 | minibuffer contents show through. Previously, there was no reliable way | |
1716 | to make sure that the minibuffer contents were visible. | |
1717 | ||
1718 | @item | |
1719 | The variable @code{temp-buffer-show-hook} has been renamed | |
1720 | @code{temp-buffer-show-function}, because its value is a single function | |
1721 | (of one argument), not a normal hook. | |
1722 | ||
1723 | @item | |
1724 | The new function @code{force-mode-line-update} causes redisplay | |
1725 | of the current buffer's mode line. | |
1726 | @end itemize | |
1727 | ||
1728 | @section Display Tables | |
1729 | ||
1730 | @cindex display table | |
1731 | You can use the @dfn{display table} feature to control how all 256 | |
1732 | possible character codes display on the screen. This is useful for | |
1733 | displaying European languages that have letters not in the ASCII | |
1734 | character set. | |
1735 | ||
1736 | The display table maps each character code into a sequence of | |
1737 | @dfn{glyphs}, each glyph being an image that takes up one character | |
1738 | position on the screen. You can also define how to display each glyph | |
1739 | on your terminal, using the @dfn{glyph table}. | |
1740 | ||
1741 | @subsection Display Tables | |
1742 | ||
1743 | Use @code{make-display-table} to create a display table. The table | |
1744 | initially has @code{nil} in all elements. | |
1745 | ||
1746 | A display table is actually an array of 261 elements. The first 256 | |
1747 | elements of a display table control how to display each possible text | |
1748 | character. The value should be @code{nil} or a vector (which is a | |
1749 | sequence of glyphs; see below). @code{nil} as an element means to | |
1750 | display that character following the usual display conventions. | |
1751 | ||
1752 | The remaining five elements of a display table serve special purposes | |
1753 | (@code{nil} means use the default stated below): | |
1754 | ||
1755 | @table @asis | |
1756 | @item 256 | |
1757 | The glyph for the end of a truncated screen line (the default for this | |
1758 | is @samp{\}). | |
1759 | @item 257 | |
1760 | The glyph for the end of a continued line (the default is @samp{$}). | |
1761 | @item 258 | |
1762 | The glyph for the indicating an octal character code (the default is | |
1763 | @samp{\}). | |
1764 | @item 259 | |
1765 | The glyph for indicating a control characters (the default is @samp{^}). | |
1766 | @item 260 | |
1767 | The vector of glyphs for indicating the presence of invisible lines (the | |
1768 | default is @samp{...}). | |
1769 | @end table | |
1770 | ||
1771 | Each buffer typically has its own display table. The display table for | |
1772 | the current buffer is stored in @code{buffer-display-table}. (This | |
1773 | variable automatically becomes local if you set it.) If this variable | |
1774 | is @code{nil}, the value of @code{standard-display-table} is used in | |
1775 | that buffer. | |
1776 | ||
1777 | Each window can have its own display table, which overrides the display | |
1778 | table of the buffer it is showing. | |
1779 | ||
1780 | If neither the selected window nor the current buffer has a display | |
1781 | table, and if @code{standard-display-table} is @code{nil}, then Emacs | |
1782 | uses the usual display conventions: | |
1783 | ||
1784 | @itemize @bullet | |
1785 | @item | |
1786 | Character codes 32 through 127 map to glyph codes 32 through 127. | |
1787 | @item | |
1788 | Codes 0 through 31 map to sequences of two glyphs, where the first glyph | |
1789 | is the ASCII code for @samp{^}. | |
1790 | @item | |
1791 | Character codes 128 through 255 map to sequences of four glyphs, where | |
1792 | the first glyph is the ASCII code for @samp{\}, and the others represent | |
1793 | digits. | |
1794 | @end itemize | |
1795 | ||
1796 | The usual display conventions are also used for any character whose | |
1797 | entry in the active display table is @code{nil}. This means that when | |
1798 | you set up a display table, you need not specify explicitly what to do | |
1799 | with each character, only the characters for which you want unusual | |
1800 | behavior. | |
1801 | ||
1802 | @subsection Glyphs | |
1803 | ||
1804 | @cindex glyph | |
1805 | A glyph stands for an image that takes up a single character position on | |
1806 | the screen. A glyph is represented in Lisp as an integer. | |
1807 | ||
1808 | @cindex glyph table | |
1809 | The meaning of each integer, as a glyph, is defined by the glyph table, | |
1810 | which is the value of the variable @code{glyph-table}. It should be a | |
1811 | vector; the @var{g}th element defines glyph code @var{g}. The possible | |
1812 | definitions of a glyph code are: | |
1813 | ||
1814 | @table @var | |
1815 | @item integer | |
1816 | Define this glyph code as an alias for code @var{integer}. | |
1817 | This is used with X windows to specify a face code. | |
1818 | ||
1819 | @item string | |
1820 | Send the characters in @var{string} to the terminal to output | |
1821 | this glyph. This alternative is not available with X Windows. | |
1822 | ||
1823 | @item @code{nil} | |
1824 | This glyph is simple. On an ordinary terminal, the glyph code mod 256 | |
1825 | is the character to output. With X, the glyph code mod 256 is character | |
1826 | to output, and the glyph code divided by 256 specifies the @dfn{face | |
1827 | code} to use while outputting it. | |
1828 | @end table | |
1829 | ||
1830 | Any glyph code beyond the length of the glyph table is automatically simple. | |
1831 | ||
1832 | A face code for X windows is the combination of a font and a color. | |
1833 | Emacs uses integers to identify face codes. You can define a new face | |
1834 | code with @code{(x-set-face @var{face-code} @var{font} @var{foreground} | |
1835 | @var{background})}. @var{face-code} is an integer from 0 to 255; it | |
1836 | specifies which face to define. The other three arguments are strings: | |
1837 | @var{font} is the name of the font to use, and @var{foreground} and | |
1838 | @var{background} specify the colors to use. | |
1839 | ||
1840 | If @code{glyph-table} is @code{nil}, then all possible glyph codes are | |
1841 | simple. | |
1842 | ||
1843 | @subsection ISO Latin 1 | |
1844 | ||
1845 | If you have a terminal that can handle the entire ISO Latin 1 character | |
1846 | set, you can arrange to use that character set as follows: | |
1847 | ||
1848 | @example | |
1849 | (require 'disp-table) | |
1850 | (standard-display-8bit 0 255) | |
1851 | @end example | |
1852 | ||
1853 | If you are editing buffers written in the ISO Latin 1 character set and | |
1854 | your terminal doesn't handle anything but ASCII, you can load the file | |
1855 | @code{iso-ascii} to set up a display table which makes the other ISO | |
1856 | characters display as sequences of ASCII characters. For example, the | |
1857 | character ``o with umlaut'' displays as @samp{@{"o@}}. | |
1858 | ||
1859 | Some European countries have terminals that don't support ISO Latin 1 | |
1860 | but do support the special characters for that country's language. You | |
1861 | can define a display table to work one language using such terminals. | |
1862 | For an example, see @file{lisp/iso-swed.el}, which handles certain | |
1863 | Swedish terminals. | |
1864 | ||
1865 | You can load the appropriate display table for your terminal | |
1866 | automatically by writing a terminal-specific Lisp file for the terminal | |
1867 | type. | |
1868 | ||
1869 | @section New Input Event Formats | |
1870 | ||
1871 | Mouse clicks, mouse movements and function keys no longer appear in the | |
1872 | input stream as characters; instead, other kinds of Lisp objects | |
1873 | represent them as input. | |
1874 | ||
1875 | @itemize @bullet | |
1876 | @item | |
1877 | An ordinary input character event consists of a @dfn{basic code} between | |
1878 | 0 and 255, plus any or all of these @dfn{modifier bits}: | |
1879 | ||
1880 | @table @asis | |
1881 | @item meta | |
1882 | The 2**23 bit in the character code indicates a character | |
1883 | typed with the meta key held down. | |
1884 | ||
1885 | @item control | |
1886 | The 2**22 bit in the character code indicates a non-@sc{ASCII} | |
1887 | control character. | |
1888 | ||
1889 | @sc{ASCII} control characters such as @kbd{C-a} have special basic | |
1890 | codes of their own, so Emacs needs no special bit to indicate them. | |
1891 | Thus, the code for @kbd{C-a} is just 1. | |
1892 | ||
1893 | But if you type a control combination not in @sc{ASCII}, such as | |
1894 | @kbd{%} with the control key, the numeric value you get is the code | |
1895 | for @kbd{%} plus 2**22 (assuming the terminal supports non-@sc{ASCII} | |
1896 | control characters). | |
1897 | ||
1898 | @item shift | |
1899 | The 2**21 bit in the character code indicates an @sc{ASCII} control | |
1900 | character typed with the shift key held down. | |
1901 | ||
1902 | For letters, the basic code indicates upper versus lower case; for | |
1903 | digits and punctuation, the shift key selects an entirely different | |
1904 | character with a different basic code. In order to keep within | |
1905 | the @sc{ASCII} character set whenever possible, Emacs avoids using | |
1906 | the 2**21 bit for those characters. | |
1907 | ||
1908 | However, @sc{ASCII} provides no way to distinguish @kbd{C-A} from | |
1909 | @kbd{C-A}, so Emacs uses the 2**21 bit in @kbd{C-A} and not in | |
1910 | @kbd{C-a}. | |
1911 | ||
1912 | @item hyper | |
1913 | The 2**20 bit in the character code indicates a character | |
1914 | typed with the hyper key held down. | |
1915 | ||
1916 | @item super | |
1917 | The 2**19 bit in the character code indicates a character | |
1918 | typed with the super key held down. | |
1919 | ||
1920 | @item alt | |
1921 | The 2**18 bit in the character code indicates a character typed with | |
1922 | the alt key held down. (On some terminals, the key labeled @key{ALT} | |
1923 | is actually the meta key.) | |
1924 | @end table | |
1925 | ||
1926 | In the future, Emacs may support a larger range of basic codes. We may | |
1927 | also move the modifier bits to larger bit numbers. Therefore, you | |
1928 | should avoid mentioning specific bit numbers in your program. Instead, | |
1929 | the way to test the modifier bits of a character is with the function | |
1930 | @code{event-modifiers} (see below). | |
1931 | ||
1932 | @item | |
1933 | Function keys are represented as symbols. The symbol's name is | |
1934 | the function key's label. For example, pressing a key labeled @key{F1} | |
1935 | places the symbol @code{f1} in the input stream. | |
1936 | ||
1937 | There are a few exceptions to the symbol naming convention: | |
1938 | ||
1939 | @table @asis | |
1940 | @item @code{kp-add}, @code{kp-decimal}, @code{kp-divide}, @dots{} | |
1941 | Keypad keys (to the right of the regular keyboard). | |
1942 | @item @code{kp-0}, @code{kp-1}, @dots{} | |
1943 | Keypad keys with digits. | |
1944 | @item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4} | |
1945 | Keypad PF keys. | |
1946 | @item @code{left}, @code{up}, @code{right}, @code{down} | |
1947 | Cursor arrow keys | |
1948 | @end table | |
1949 | ||
1950 | You can use the modifier keys @key{CTRL}, @key{META}, @key{HYPER}, | |
1951 | @key{SUPER}, @key{ALT} and @key{SHIFT} with function keys. The way | |
1952 | to represent them is with prefixes in the symbol name: | |
1953 | ||
1954 | @table @samp | |
1955 | @item A- | |
1956 | The alt modifier. | |
1957 | @item C- | |
1958 | The control modifier. | |
1959 | @item H- | |
1960 | The hyper modifier. | |
1961 | @item M- | |
1962 | The meta modifier. | |
1963 | @item s- | |
1964 | The super modifier. | |
1965 | @item S- | |
1966 | The shift modifier. | |
1967 | @end table | |
1968 | ||
1969 | Thus, the symbol for the key @key{F3} with @key{META} held down is | |
1970 | kbd{M-@key{F3}}. When you use more than one prefix, we recommend you | |
1971 | write them in alphabetical order (though the order does not matter in | |
1972 | arguments to the key-binding lookup and modification functions). | |
1973 | ||
1974 | @item | |
1975 | Mouse events are represented as lists. | |
1976 | ||
1977 | If you press a mouse button and release it at the same location, this | |
1978 | generates a ``click'' event. Mouse click events have this form: | |
1979 | ||
1980 | @example | |
1981 | (@var{button-symbol} | |
1982 | (@var{window} (@var{column} . @var{row}) | |
1983 | @var{buffer-pos} @var{timestamp})) | |
1984 | @end example | |
1985 | ||
1986 | Here is what the elements normally mean: | |
1987 | ||
1988 | @table @var | |
1989 | @item button-symbol | |
1990 | indicates which mouse button was used. It is one of the symbols | |
1991 | @code{mouse-1}, @code{mouse-2}, @dots{}, where the buttons are numbered | |
1992 | numbered left to right. | |
1993 | ||
1994 | You can also use prefixes @samp{A-}, @samp{C-}, @samp{H-}, @samp{M-}, | |
1995 | @samp{S-} and @samp{s-} for modifiers alt, control, hyper, meta, shift | |
1996 | and super, just as you would with function keys. | |
1997 | ||
1998 | @item window | |
1999 | is the window in which the click occurred. | |
2000 | ||
2001 | @item column | |
2002 | @itemx row | |
2003 | are the column and row of the click, relative to the top left corner of | |
2004 | @var{window}, which is @code{(0 . 0)}. | |
2005 | ||
2006 | @item buffer-pos | |
2007 | is the buffer position of the character clicked on. | |
2008 | ||
2009 | @item timestamp | |
2010 | is the time at which the event occurred, in milliseconds. (Since this | |
2011 | value wraps around the entire range of Emacs Lisp integers in about five | |
2012 | hours, it is useful only for relating the times of nearby events.) | |
2013 | @end table | |
2014 | ||
2015 | The meanings of @var{buffer-pos}, @var{row} and @var{column} are | |
2016 | somewhat different when the event location is in a special part of the | |
2017 | screen, such as the mode line or a scroll bar. | |
2018 | ||
2019 | If the position is in the window's scroll bar, then @var{buffer-pos} is | |
2020 | the symbol @code{vertical-scrollbar} or @code{horizontal-scrollbar}, and | |
2021 | the pair @code{(@var{column} . @var{row})} is instead a pair | |
2022 | @code{(@var{portion} . @var{whole})}, where @var{portion} is the | |
2023 | distance of the click from the top or left end of the scroll bar, and | |
2024 | @var{whole} is the length of the entire scroll bar. | |
2025 | ||
2026 | If the position is on a mode line or the vertical line separating | |
2027 | @var{window} from its neighbor to the right, then @var{buffer-pos} is | |
2028 | the symbol @code{mode-line} or @code{vertical-line}. In this case | |
2029 | @var{row} and @var{column} do not have meaningful data. | |
2030 | ||
2031 | @item | |
2032 | Releasing a mouse button above a different character position | |
2033 | generates a ``drag'' event, which looks like this: | |
2034 | ||
2035 | @example | |
2036 | (@var{button-symbol} | |
2037 | (@var{window1} (@var{column1} . @var{row1}) | |
2038 | @var{buffer-pos1} @var{timestamp1}) | |
2039 | (@var{window2} (@var{column2} . @var{row2}) | |
2040 | @var{buffer-pos2} @var{timestamp2})) | |
2041 | @end example | |
2042 | ||
2043 | The name of @var{button-symbol} contains the prefix @samp{drag-}. The | |
2044 | second and third elements of the event give the starting and ending | |
2045 | position of the drag. | |
2046 | ||
2047 | The @samp{drag-} prefix follows the modifier key prefixes such as | |
2048 | @samp{C-} and @samp{M-}. | |
2049 | ||
2050 | If @code{read-key-sequence} receives a drag event which has no key | |
2051 | binding, and the corresponding click event does have a binding, it | |
2052 | changes the drag event into a click event at the drag's starting | |
2053 | position. This means that you don't have to distinguish between click | |
2054 | and drag events unless you want to. | |
2055 | ||
2056 | @item | |
2057 | Click and drag events happen when you release a mouse button. Another | |
2058 | kind of event happens when you press a button. It looks just like a | |
2059 | click event, except that the name of @var{button-symbol} contains the | |
2060 | prefix @samp{down-}. The @samp{down-} prefix follows the modifier key | |
2061 | prefixes such as @samp{C-} and @samp{M-}. | |
2062 | ||
2063 | The function @code{read-key-sequence}, and the Emacs command loop, | |
2064 | ignore any down events that don't have command bindings. This means | |
2065 | that you need not worry about defining down events unless you want them | |
2066 | to do something. The usual reason to define a down event is so that you | |
2067 | can track mouse motion until the button is released. | |
2068 | ||
2069 | @item | |
2070 | For example, if the user presses and releases the left mouse button over | |
2071 | the same location, Emacs generates a sequence of events like this: | |
2072 | ||
2073 | @smallexample | |
2074 | (down-mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864320)) | |
2075 | (mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864180)) | |
2076 | @end smallexample | |
2077 | ||
2078 | Or, while holding the control key down, the user might hold down the | |
2079 | second mouse button, and drag the mouse from one line to the next. | |
2080 | That produces two events, as shown here: | |
2081 | ||
2082 | @smallexample | |
2083 | (C-down-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219)) | |
2084 | (C-drag-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219) | |
2085 | (#<window 18 on NEWS> 3510 (0 . 28) -729648)) | |
2086 | @end smallexample | |
2087 | ||
2088 | Or, while holding down the meta and shift keys, the user might press | |
2089 | the second mouse button on the window's mode line, and then drag the | |
2090 | mouse into another window. That produces an event like this: | |
2091 | ||
2092 | @smallexample | |
2093 | (M-S-down-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844)) | |
2094 | (M-S-drag-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844) | |
2095 | (#<window 20 on carlton-sanskrit.tex> 161 (33 . 3) | |
2096 | -453816)) | |
2097 | @end smallexample | |
2098 | ||
2099 | @item | |
2100 | A key sequence that starts with a mouse click is read using the keymaps | |
2101 | of the buffer in the window clicked on, not the current buffer. | |
2102 | ||
2103 | This does not imply that clicking in a window selects that window or its | |
2104 | buffer. The execution of the command begins with no change in the | |
2105 | selected window or current buffer. However, the command can switch | |
2106 | windows or buffers if programmed to do so. | |
2107 | ||
2108 | @item | |
2109 | Mouse motion events are represented by lists. During the execution of | |
2110 | the body of a @code{track-mouse} form, moving the mouse generates events | |
2111 | that look like this: | |
2112 | ||
2113 | @example | |
2114 | (mouse-movement (@var{window} (@var{column} . @var{row}) | |
2115 | @var{buffer-pos} @var{timestamp})) | |
2116 | @end example | |
2117 | ||
2118 | The second element of the list describes the current position of the | |
2119 | mouse, just as in a mouse click event. | |
2120 | ||
2121 | Outside of @code{track-mouse} forms, Emacs does not generate events for | |
2122 | mere motion of the mouse, and these events do not appear. | |
2123 | ||
2124 | @item | |
2125 | Focus shifts between frames are represented by lists. | |
2126 | ||
2127 | When the mouse shifts temporary input focus from one frame to another, | |
2128 | Emacs generates an event like this: | |
2129 | ||
2130 | @example | |
2131 | (switch-frame @var{new-frame}) | |
2132 | @end example | |
2133 | ||
2134 | @noindent | |
2135 | where @var{new-frame} is the frame switched to. | |
2136 | ||
2137 | In X windows, most window managers are set up so that just moving the | |
2138 | mouse into a window is enough to set the focus there. As far as the | |
2139 | user concern, Emacs behaves consistently with this. However, there is | |
2140 | no need for the Lisp program to know about the focus change until some | |
2141 | other kind of input arrives. So Emacs generates the focus event only | |
2142 | when the user actually types a keyboard key or presses a mouse button in | |
2143 | the new frame; just moving the mouse between frames does not generate a | |
2144 | focus event. | |
2145 | ||
2146 | The global key map usually binds this event to the | |
2147 | @code{internal-select-frame} function, so that characters typed at a | |
2148 | frame apply to that frame's selected window. | |
2149 | ||
2150 | If the user switches frames in the middle of a key sequence, then Emacs | |
2151 | delays the @code{switch-frame} event until the key sequence is over. | |
2152 | For example, suppose @kbd{C-c C-a} is a key sequence in the current | |
2153 | buffer's keymaps. If the user types @kbd{C-c}, moves the mouse to | |
2154 | another frame, and then types @kbd{C-a}, @code{read-key-sequence} | |
2155 | returns the sequence @code{"\C-c\C-a"}, and the next call to | |
2156 | @code{read-event} or @code{read-key-sequence} will return the | |
2157 | @code{switch-frame} event. | |
2158 | @end itemize | |
2159 | ||
2160 | @section Working with Input Events | |
2161 | ||
2162 | @itemize @bullet | |
2163 | @item | |
2164 | Functions which work with key sequences now handle non-character | |
2165 | events. Functions like @code{define-key}, @code{global-set-key}, and | |
2166 | @code{local-set-key} used to accept strings representing key sequences; | |
2167 | now, since events may be arbitrary lisp objects, they also accept | |
2168 | vectors. The function @code{read-key-sequence} may return a string or a | |
2169 | vector, depending on whether or not the sequence read contains only | |
2170 | characters. | |
2171 | ||
2172 | List events may be represented by the symbols at their head; to bind | |
2173 | clicks of the left mouse button, you need only present the symbol | |
2174 | @code{mouse-1}, not an entire mouse click event. If you do put an event | |
2175 | which is a list in a key sequence, only the event's head symbol is used | |
2176 | in key lookups. | |
2177 | ||
2178 | For example, to globally bind the left mouse button to the function | |
2179 | @code{mouse-set-point}, you could evaluate this: | |
2180 | ||
2181 | @example | |
2182 | (global-set-key [mouse-1] 'mouse-set-point) | |
2183 | @end example | |
2184 | ||
2185 | To bind the sequence @kbd{C-c @key{F1}} to the command @code{tex-view} | |
2186 | in @code{tex-mode-map}, you could evaluate this: | |
2187 | ||
2188 | @example | |
2189 | (define-key tex-mode-map [?\C-c f1] 'tex-view) | |
2190 | @end example | |
2191 | ||
2192 | To find the binding for the function key labeled @key{NEXT} in | |
2193 | @code{minibuffer-local-map}, you could evaluate this: | |
2194 | ||
2195 | @example | |
2196 | (lookup-key minibuffer-local-map [next]) | |
2197 | @result{} next-history-element | |
2198 | @end example | |
2199 | ||
2200 | If you call the function @code{read-key-sequence} and then press | |
2201 | @kbd{C-x C-@key{F5}}, here is how it behaves: | |
2202 | ||
2203 | @example | |
2204 | (read-key-sequence "Press `C-x C-F5': ") | |
2205 | @result{} [24 C-f5] | |
2206 | @end example | |
2207 | ||
2208 | Note that @samp{24} is the character @kbd{C-x}. | |
2209 | ||
2210 | @item | |
2211 | The documentation functions (@code{single-key-description}, | |
2212 | @code{key-description}, etc.) now handle the new event types. Wherever | |
2213 | a string of keyboard input characters was acceptable in previous | |
2214 | versions of Emacs, a vector of events should now work. | |
2215 | ||
2216 | @item | |
2217 | Special parts of a window can have their own bindings for mouse events. | |
2218 | ||
2219 | When mouse events occur in special parts of a window, such as a mode | |
2220 | line or a scroll bar, the event itself shows nothing special---only the | |
2221 | symbol that would normally represent that mouse button and modifier | |
2222 | keys. The information about the screen region is kept in other parts | |
2223 | of the event list. But @code{read-key-sequence} translates this | |
2224 | information into imaginary prefix keys, all of which are symbols: | |
2225 | @code{mode-line}, @code{vertical-line}, @code{horizontal-scrollbar} and | |
2226 | @code{vertical-scrollbar}. | |
2227 | ||
2228 | For example, if you call @code{read-key-sequence} and then click the | |
2229 | mouse on the window's mode line, this is what happens: | |
2230 | ||
2231 | @smallexample | |
2232 | (read-key-sequence "Click on the mode line: ") | |
2233 | @result{} [mode-line (mouse-1 (#<window 6 on NEWS> mode-line | |
2234 | (40 . 63) 5959987))] | |
2235 | @end smallexample | |
2236 | ||
2237 | You can define meanings for mouse clicks in special window regions by | |
2238 | defining key sequences using these imaginary prefix keys. For example, | |
2239 | here is how to bind the third mouse button on a window's mode line | |
2240 | delete the window: | |
2241 | ||
2242 | @example | |
2243 | (global-set-key [mode-line mouse-3] 'mouse-delete-window) | |
2244 | @end example | |
2245 | ||
2246 | Here's how to bind the middle button (modified by @key{META}) on the | |
2247 | vertical line at the right of a window to scroll the window to the | |
2248 | left. | |
2249 | ||
2250 | @example | |
2251 | (global-set-key [vertical-line M-mouse-2] 'scroll-left) | |
2252 | @end example | |
2253 | ||
2254 | @item | |
2255 | Decomposing an event symbol. | |
2256 | ||
2257 | Each symbol used to identify a function key or mouse button has a | |
2258 | property named @code{event-symbol-elements}, which is a list containing | |
2259 | an unmodified version of the symbol, followed by modifiers the symbol | |
2260 | name contains. The modifiers are symbols; they include @code{shift}, | |
2261 | @code{control}, and @code{meta}. In addition, a mouse event symbol has | |
2262 | one of @code{click}, @code{drag}, and @code{down}. For example: | |
2263 | ||
2264 | @example | |
2265 | (get 'f5 'event-symbol-elements) | |
2266 | @result{} (f5) | |
2267 | (get 'C-f5 'event-symbol-elements) | |
2268 | @result{} (f5 control) | |
2269 | (get 'M-S-f5 'event-symbol-elements) | |
2270 | @result{} (f5 meta shift) | |
2271 | (get 'mouse-1 'event-symbol-elements) | |
2272 | @result{} (mouse-1 click) | |
2273 | (get 'down-mouse-1 'event-symbol-elements) | |
2274 | @result{} (mouse-1 down) | |
2275 | @end example | |
2276 | ||
2277 | Note that the @code{event-symbol-elements} property for a mouse click | |
2278 | explicitly contains @code{click}, but the event symbol name itself does | |
2279 | not contain @samp{click}. | |
2280 | ||
2281 | @item | |
2282 | Use @code{read-event} to read input if you want to accept any kind of | |
2283 | event. The old function @code{read-char} now discards events other than | |
2284 | keyboard characters. | |
2285 | ||
2286 | @item | |
2287 | @code{last-command-char} and @code{last-input-char} can now hold any | |
2288 | kind of event. | |
2289 | ||
2290 | @item | |
2291 | The new variable @code{unread-command-events} is much like | |
2292 | @code{unread-command-char}. Its value is a list of events of any type, | |
2293 | to be processed as command input in order of appearance in the list. | |
2294 | ||
2295 | @item | |
2296 | The function @code{this-command-keys} may return a string or a vector, | |
2297 | depending on whether or not the sequence read contains only characters. | |
2298 | You may need to upgrade code which uses this function. | |
2299 | ||
2300 | The function @code{recent-keys} now returns a vector of events. | |
2301 | You may need to upgrade code which uses this function. | |
2302 | ||
2303 | @item | |
2304 | A keyboard macro's definition can now be either a string or a vector. | |
2305 | All that really matters is what elements it has. If the elements are | |
2306 | all characters, then the macro can be a string; otherwise, it has to be | |
2307 | a vector. | |
2308 | ||
2309 | @item | |
2310 | The variable @code{last-event-frame} records which frame the last input | |
2311 | event was directed to. Usually this is the frame that was selected when | |
2312 | the event was generated, but if that frame has redirected input focus to | |
2313 | another frame, @code{last-event-frame} is the frame to which the event | |
2314 | was redirected. | |
2315 | ||
2316 | @item | |
2317 | The interactive specification now allows a new code letter @samp{e} to | |
2318 | simplify commands bound to events which are lists. This code supplies | |
2319 | as an argument the complete event object. | |
2320 | ||
2321 | You can use @samp{e} more than once in a single command's interactive | |
2322 | specification. If the key sequence which invoked the command has | |
2323 | @var{n} events with parameters, the @var{n}th @samp{e} provides the | |
2324 | @var{n}th parameterized event. Events which are not lists, such as | |
2325 | function keys and ASCII keystrokes, do not count where @samp{e} is | |
2326 | concerned. | |
2327 | ||
2328 | @item | |
2329 | You can extract the starting and ending position values from a mouse | |
2330 | button or motion event using the two functions @code{event-start} and | |
2331 | @code{event-end}. These two functions return different values for drag | |
2332 | and motion events; for click and button-down events, they both return | |
2333 | the position of the event. | |
2334 | ||
2335 | @item | |
2336 | The position, a returned by @code{event-start} and @code{event-end}, is | |
2337 | a list of this form: | |
2338 | ||
2339 | @example | |
2340 | (@var{window} @var{buffer-position} (@var{col} . @var{row}) @var{timestamp}) | |
2341 | @end example | |
2342 | ||
2343 | You can extract parts of this list with the functions | |
2344 | @code{posn-window}, @code{posn-point}, @code{posn-col-row}, and | |
2345 | @code{posn-timestamp}. | |
2346 | ||
2347 | @item | |
2348 | The function @code{scroll-bar-scale} is useful for computing where to | |
2349 | scroll to in response to a mouse button event from a scroll bar. It | |
2350 | takes two arguments, @var{ratio} and @var{total}, and in effect | |
2351 | multiplies them. We say ``in effect'' because @var{ratio} is not a | |
2352 | number; rather a pair @code{(@var{num} . @var{denom}). | |
2353 | ||
2354 | Here's the usual way to use @code{scroll-bar-scale}: | |
2355 | ||
2356 | @example | |
2357 | (scroll-bar-scale (posn-col-row (event-start event)) | |
2358 | (buffer-size)) | |
2359 | @end example | |
2360 | @end itemize | |
2361 | ||
2362 | @section Putting Keyboard Events in Strings | |
2363 | ||
2364 | In most of the places where strings are used, we conceptualize the | |
2365 | string as containing text characters---the same kind of characters found | |
2366 | in buffers or files. Occasionally Lisp programs use strings which | |
2367 | conceptually contain keyboard characters; for example, they may be key | |
2368 | sequences or keyboard macro definitions. There are special rules for | |
2369 | how to put keyboard characters into a string, because they are not | |
2370 | limited to the range of 0 to 255 as text characters are. | |
2371 | ||
2372 | A keyboard character typed using the @key{META} key is called a | |
2373 | @dfn{meta character}. The numeric code for such an event includes the | |
2374 | 2**23 bit; it does not even come close to fitting in a string. However, | |
2375 | earlier Emacs versions used a different representation for these | |
2376 | characters, which gave them codes in the range of 128 to 255. That did | |
2377 | fit in a string, and many Lisp programs contain string constants that | |
2378 | use @samp{\M-} to express meta characters, especially as the argument to | |
2379 | @code{define-key} and similar functions. | |
2380 | ||
2381 | We provide backward compatibility to run those programs with special | |
2382 | rules for how to put a keyboard character event in a string. Here are | |
2383 | the rules: | |
2384 | ||
2385 | @itemize @bullet | |
2386 | @item | |
2387 | If the keyboard event value is in the range of 0 to 127, it can go in the | |
2388 | string unchanged. | |
2389 | ||
2390 | @item | |
2391 | The meta variants of those events, with codes in the range of 2**23 to | |
2392 | 2**23+127, can also go in the string, but you must change their numeric | |
2393 | values. You must set the 2**7 bit instead of the 2**23 bit, resulting | |
2394 | in a value between 128 and 255. | |
2395 | ||
2396 | @item | |
2397 | Other keyboard character events cannot fit in a string. This includes | |
2398 | keyboard events in the range of 128 to 255. | |
2399 | @end itemize | |
2400 | ||
2401 | Functions such as @code{read-key-sequence} that can construct strings | |
2402 | containing events follow these rules. | |
2403 | ||
2404 | When you use the read syntax @samp{\M-} in a string, it produces a | |
2405 | code in the range of 128 to 255---the same code that you get if you | |
2406 | modify the corresponding keyboard event to put it in the string. Thus, | |
2407 | meta events in strings work consistently regardless of how they get into | |
2408 | the strings. | |
2409 | ||
2410 | New programs can avoid dealing with these rules by using vectors | |
2411 | instead of strings for key sequences when there is any possibility that | |
2412 | these issues might arise. | |
2413 | ||
2414 | The reason we changed the representation of meta characters as | |
2415 | keyboard events is to make room for basic character codes beyond 127, | |
2416 | and support meta variants of such larger character codes. | |
2417 | ||
2418 | @section Menus | |
2419 | ||
2420 | You can now define menus conveniently as keymaps. Menus are normally | |
2421 | used with the mouse, but they can work with the keyboard also. | |
2422 | ||
2423 | @subsection Defining Menus | |
2424 | ||
2425 | A keymap is suitable for menu use if it has an @dfn{overall prompt | |
2426 | string}, which is a string that appears as an element of the keymap. It | |
2427 | should describes the purpose of the menu. The easiest way to construct | |
2428 | a keymap with a prompt string is to specify the string as an argument | |
2429 | when you run @code{make-keymap} or @code{make-sparse-keymap}. | |
2430 | ||
2431 | The individual bindings in the menu keymap should also have prompt | |
2432 | strings; these strings are the items in the menu. A binding with a | |
2433 | prompt string looks like this: | |
2434 | ||
2435 | @example | |
2436 | (@var{char} @var{string} . @var{real-binding}) | |
2437 | @end example | |
2438 | ||
2439 | As far as @code{define-key} is concerned, the string is part of the | |
2440 | character's binding---the binding looks like this: | |
2441 | ||
2442 | @example | |
2443 | (@var{string} . @var{real-binding}). | |
2444 | @end example | |
2445 | ||
2446 | However, only @var{real-binding} is used for executing the key. | |
2447 | ||
2448 | You can also supply a second string, called the help string, as follows: | |
2449 | ||
2450 | @example | |
2451 | (@var{char} @var{string} @var{help-string} . @var{real-binding}) | |
2452 | @end example | |
2453 | ||
2454 | Currently Emacs does not actually use @var{help-string}; it knows only | |
2455 | how to ignore @var{help-string} in order to extract @var{real-binding}. | |
2456 | In the future we hope to make @var{help-string} serve as longer | |
2457 | documentation for the menu item, available on request. | |
2458 | ||
2459 | The prompt string for a binding should be short---one or two words. Its | |
2460 | meaning should describe the command it corresponds to. | |
2461 | ||
2462 | If @var{real-binding} is @code{nil}, then @var{string} appears in the | |
2463 | menu but cannot be selected. | |
2464 | ||
2465 | If @var{real-binding} is a symbol, and has a non-@code{nil} | |
2466 | @code{menu-enable} property, that property is an expression which | |
2467 | controls whether the menu item is enabled. Every time the keymap is | |
2468 | used to display a menu, Emacs evaluates the expression, and it enables | |
2469 | the menu item only if the expression's value is non-@code{nil}. When a | |
2470 | menu item is disabled, it is displayed in a ``fuzzy'' fashion, and | |
2471 | cannot be selected with the mouse. | |
2472 | ||
2473 | @subsection Menus and the Mouse | |
2474 | ||
2475 | The way to make a menu keymap produce a menu is to make it the | |
2476 | definition of a prefix key. | |
2477 | ||
2478 | When the prefix key ends with a mouse event, Emacs handles the menu | |
2479 | keymap by popping up a visible menu that you can select from with the | |
2480 | mouse. When you click on a menu item, the event generated is whatever | |
2481 | character or symbol has the binding which brought about that menu item. | |
2482 | ||
2483 | A single keymap can appear as multiple panes, if you explicitly | |
2484 | arrange for this. The way to do this is to make a keymap for each | |
2485 | pane, then create a binding for each of those maps in the main keymap | |
2486 | of the menu. Give each of these bindings a prompt string that starts | |
2487 | with @samp{@@}. The rest of the prompt string becomes the name of the | |
2488 | pane. See the file @file{lisp/mouse.el} for an example of this. Any | |
2489 | ordinary bindings with prompt strings are grouped into one pane, which | |
2490 | appears along with the other panes explicitly created for the | |
2491 | submaps. | |
2492 | ||
2493 | You can also get multiple panes from separate keymaps. The full | |
2494 | definition of a prefix key always comes from merging the definitions | |
2495 | supplied by the various active keymaps (minor modes, local, and | |
2496 | global). When more than one of these keymaps is a menu, each of them | |
2497 | makes a separate pane or panes. | |
2498 | ||
2499 | @subsection Menus and the Keyboard | |
2500 | ||
2501 | When a prefix key ending with a keyboard event (a character or function | |
2502 | key) has a definition that is a menu keymap, you can use the keyboard | |
2503 | to choose a menu item. | |
2504 | ||
2505 | Emacs displays the menu alternatives in the echo area. If they don't | |
2506 | all fit at once, type @key{SPC} to see the next line of alternatives. | |
2507 | If you keep typing @key{SPC}, you eventually get to the end of the menu | |
2508 | and then cycle around to the beginning again. | |
2509 | ||
2510 | When you have found the alternative you want, type the corresponding | |
2511 | character---the one whose binding is that alternative. | |
2512 | ||
2513 | In a menu intended for keyboard use, each menu item must clearly | |
2514 | indicate what character to type. The best convention to use is to make | |
2515 | the character the first letter of the menu item prompt string. That is | |
2516 | something users will understand without being told. | |
2517 | ||
2518 | @subsection The Menu Bar | |
2519 | ||
2520 | Under X Windows, each frame can have a @dfn{menu bar}---a permanently | |
2521 | displayed menu stretching horizontally across the top of the frame. The | |
2522 | items of the menu bar are the subcommands of the fake ``function key'' | |
2523 | @code{menu-bar}, as defined by all the active keymaps. | |
2524 | ||
2525 | To add an item to the menu bar, invent a fake ``function key'' of your | |
2526 | own (let's call it @var{key}), and make a binding for the key sequence | |
2527 | @code{[menu-bar @var{key}]}. Most often, the binding is a menu keymap, | |
2528 | so that pressing a button on the menu bar item leads to another menu. | |
2529 | ||
2530 | In order for a frame to display a menu bar, its @code{menu-bar-lines} | |
2531 | property must be greater than zero. Emacs uses just one line for the | |
2532 | menu bar itself; if you specify more than one line, the other lines | |
2533 | serve to separate the menu bar from the windows in the frame. We | |
2534 | recommend you try one or two as the @code{menu-bar-lines} value. | |
2535 | ||
2536 | @section Keymaps | |
2537 | ||
2538 | @itemize @bullet | |
2539 | @item | |
2540 | The representation of keymaps has changed to support the new event | |
2541 | types. All keymaps now have the form @code{(keymap @var{element} | |
2542 | @var{element} @dots{})}. Each @var{element} takes one of the following | |
2543 | forms: | |
2544 | ||
2545 | @table @asis | |
2546 | @item @var{prompt-string} | |
2547 | A string as an element of the keymap marks the keymap as a menu, and | |
2548 | serves as the overal prompt string for it. | |
2549 | ||
2550 | @item @code{(@var{key} . @var{binding})} | |
2551 | A cons cell binds @var{key} to @var{definition}. Here @var{key} may be | |
2552 | any sort of event head---a character, a function key symbol, or a mouse | |
2553 | button symbol. | |
2554 | ||
2555 | @item @var{vector} | |
2556 | A vector of 128 elements binds all the ASCII characters; the @var{n}th | |
2557 | element holds the binding for character number @var{n}. | |
2558 | ||
2559 | @item @code{(t . @var{binding})} | |
2560 | A cons cell whose @sc{car} is @code{t} is a default binding; anything | |
2561 | not bound by previous keymap elements is given @var{binding} as its | |
2562 | binding. | |
2563 | ||
2564 | Default bindings are important because they allow a keymap to bind all | |
2565 | possible events without having to enumerate all the possible function | |
2566 | keys and mouse clicks, with all possible modifier prefixes. | |
2567 | ||
2568 | The function @code{lookup-key} (and likewise other functions for | |
2569 | examining a key binding) normally report only explicit bindings of the | |
2570 | specified key sequence; if there is none, they return @code{nil}, even | |
2571 | if there is a default binding that would apply to that key sequence if | |
2572 | it were actually typed in. However, these functions now take an | |
2573 | optional argument @var{accept-defaults} which, if non-@code{nil}, says | |
2574 | to consider default bindings. | |
2575 | ||
2576 | Note that if a vector in the keymap binds an ASCII character to | |
2577 | @code{nil} (thus making it ``unbound''), the default binding does not | |
2578 | apply to the character. Think of the vector element as an explicit | |
2579 | binding of @code{nil}. | |
2580 | ||
2581 | Note also that if the keymap for a minor or major mode contains a | |
2582 | default binding, it completely masks out any lower-priority keymaps. | |
2583 | @end table | |
2584 | ||
2585 | @item | |
2586 | A keymap can now inherit from another keymap. Do do this, make the | |
2587 | latter keymap the ``tail'' of the new one. Such a keymap looks like | |
2588 | this: | |
2589 | ||
2590 | @example | |
2591 | (keymap @var{bindings}@dots{} . @var{other-keymap}) | |
2592 | @end example | |
2593 | ||
2594 | The effect is that this keymap inherits all the bindings of | |
2595 | @var{other-keymap}, but can add to them or override them with | |
2596 | @var{bindings}. Subsequent changes in the bindings of | |
2597 | @var{other-keymap} @emph{do} affect this keymap. | |
2598 | ||
2599 | For example, | |
2600 | ||
2601 | @example | |
2602 | (setq my-mode-map (cons 'keymap text-mode-map)) | |
2603 | @end example | |
2604 | ||
2605 | @noindent | |
2606 | makes a keymap that by default inherits all the bindings of Text | |
2607 | mode---whatever they may be at the time a key is looked up. Any | |
2608 | bindings made explicitly in @code{my-mode-map} override the bindings | |
2609 | inherited from Text mode, however. | |
2610 | ||
2611 | @item | |
2612 | Minor modes can now have local keymaps. Thus, a key can act a special | |
2613 | way when a minor mode is in effect, and then revert to the major mode or | |
2614 | global definition when the minor mode is no longer in effect. The | |
2615 | precedence of keymaps is now: minor modes (in no particular order), then | |
2616 | major mode, and lastly the global map. | |
2617 | ||
2618 | The new @code{current-minor-mode-maps} function returns a list of all | |
2619 | the keymaps of currently enabled minor modes, in the other that they | |
2620 | apply. | |
2621 | ||
2622 | To set up a keymap for a minor mode, add an element to the alist | |
2623 | @code{minor-mode-map-alist}. Its elements look like this: | |
2624 | ||
2625 | @example | |
2626 | (@var{symbol} . @var{keymap}) | |
2627 | @end example | |
2628 | ||
2629 | The keymap @var{keymap} is active whenever @var{symbol} has a | |
2630 | non-@code{nil} value. Use for @var{symbol} the variable which indicates | |
2631 | whether the minor mode is enabled. | |
2632 | ||
2633 | When more than one minor mode keymap is active, their order of | |
2634 | precedence is the order of @code{minor-mode-map-alist}. But you should | |
2635 | design minor modes so that they don't interfere with each other, and if | |
2636 | you do this properly, the order will not matter. | |
2637 | ||
2638 | The function @code{minor-mode-key-binding} returns a list of all the | |
2639 | active minor mode bindings of @var{key}. More precisely, it returns an | |
2640 | alist of pairs @code{(@var{modename} . @var{binding})}, where | |
2641 | @var{modename} is the the variable which enables the minor mode, and | |
2642 | @var{binding} is @var{key}'s definition in that mode. If @var{key} has | |
2643 | no minor-mode bindings, the value is @code{nil}. | |
2644 | ||
2645 | If the first binding is a non-prefix, all subsequent bindings from other | |
2646 | minor modes are omitted, since they would be completely shadowed. | |
2647 | Similarly, the list omits non-prefix bindings that follow prefix | |
2648 | bindings. | |
2649 | ||
2650 | @item | |
2651 | The new function @code{copy-keymap} copies a keymap, producing a new | |
2652 | keymap with the same key bindings in it. If the keymap contains other | |
2653 | keymaps directly, these subkeymaps are copied recursively. | |
2654 | ||
2655 | If you want to, you can define a prefix key with a binding that is a | |
2656 | symbol whose function definition is another keymap. In this case, | |
2657 | @code{copy-keymap} does not look past the symbol; it doesn't copy the | |
2658 | keymap inside the symbol. | |
2659 | ||
2660 | @item | |
2661 | @code{substitute-key-definition} now accepts an optional fourth | |
2662 | argument, which is a keymap to use as a template. | |
2663 | ||
2664 | @example | |
2665 | (substitute-key-definition olddef newdef keymap oldmap) | |
2666 | @end example | |
2667 | ||
2668 | @noindent | |
2669 | finds all characters defined in @var{oldmap} as @var{olddef}, | |
2670 | and defines them in @var{keymap} as @var{newdef}. | |
2671 | ||
2672 | In addition, this function now operates recursively on the keymaps that | |
2673 | define prefix keys within @var{keymap} and @var{oldmap}. | |
2674 | @end itemize | |
2675 | ||
2676 | @section Minibuffer Features | |
2677 | ||
2678 | The minibuffer input functions @code{read-from-minibuffer} and | |
2679 | @code{completing-read} have new features. | |
2680 | ||
2681 | @subsection Minibuffer History | |
2682 | ||
2683 | A new optional argument @var{hist} specifies which history list to use. | |
2684 | If you specify a variable (a symbol), that variable is the history | |
2685 | list. If you specify a cons cell @code{(@var{variable} | |
2686 | . @var{startpos})}, then @var{variable} is the history list variable, | |
2687 | and @var{startpos} specifies the initial history position (an integer, | |
2688 | counting from zero which specifies the most recent element of the | |
2689 | history). | |
2690 | ||
2691 | If you specify @var{startpos}, then you should also specify that element | |
2692 | of the history as @var{initial-input}, for consistency. | |
2693 | ||
2694 | If you don't specify @var{hist}, then the default history list | |
2695 | @code{minibuffer-history} is used. Other standard history lists that | |
2696 | you can use when appropriate include @code{query-replace-history}, | |
2697 | @code{command-history}, and @code{file-name-history}. | |
2698 | ||
2699 | The value of the history list variable is a list of strings, most recent | |
2700 | first. You should set a history list variable to @code{nil} before | |
2701 | using it for the first time. | |
2702 | ||
2703 | @code{read-from-minibuffer} and @code{completing-read} add new elements | |
2704 | to the history list automatically, and provide commands to allow the | |
2705 | user to reuse items on the list. The only thing your program needs to | |
2706 | do to use a history list is to initialize it and to pass its name to the | |
2707 | input functions when you wish. But it is safe to modify the list by | |
2708 | hand when the minibuffer input functions are not using it. | |
2709 | ||
2710 | @subsection Other Minibuffer Features | |
2711 | ||
2712 | The @var{initial} argument to @code{read-from-minibufer} and other | |
2713 | minibuffer input functions can now be a cons cell @code{(@var{string} | |
2714 | . @var{position})}. This means to start off with @var{string} in the | |
2715 | minibuffer, but put the cursor @var{position} characters from the | |
2716 | beginning, rather than at the end. | |
2717 | ||
2718 | In @code{read-no-blanks-input}, the @var{initial} argument is now | |
2719 | optional; if it is omitted, the initial input string is the empty | |
2720 | string. | |
2721 | ||
2722 | @section New Features for Defining Commands | |
2723 | ||
2724 | @itemize @bullet | |
2725 | @item | |
2726 | If the interactive specification begins with @samp{@@}, this means to | |
2727 | select the window under the mouse. This selection takes place before | |
2728 | doing anything else with the command. | |
2729 | ||
2730 | You can use both @samp{@@} and @samp{*} together in one command; they | |
2731 | are processed in order of appearance. | |
2732 | ||
2733 | @item | |
2734 | Prompts in an interactive specification can incorporate the values of | |
2735 | the preceding arguments. Emacs replaces @samp{%}-sequences (as used | |
2736 | with the @code{format} function) in the prompt with the interactive | |
2737 | arguments that have been read so far. For example, a command with this | |
2738 | interactive specification | |
2739 | ||
2740 | @example | |
2741 | (interactive "sReplace: \nsReplace %s with: ") | |
2742 | @end example | |
2743 | ||
2744 | @noindent | |
2745 | prompts for the first argument with @samp{Replace: }, and then prompts | |
2746 | for the second argument with @samp{Replace @var{foo} with: }, where | |
2747 | @var{foo} is the string read as the first argument. | |
2748 | ||
2749 | @item | |
2750 | If a command name has a property @code{enable-recursive-minibuffers} | |
2751 | which is non-@code{nil}, then the command can use the minibuffer to read | |
2752 | arguments even if it is invoked from the minibuffer. The minibuffer | |
2753 | command @code{next-matching-history-element} (normally bound to | |
2754 | @kbd{M-s} in the minibuffer) uses this feature. | |
2755 | @end itemize | |
2756 | ||
2757 | @section New Features for Reading Input | |
2758 | ||
2759 | @itemize @bullet | |
2760 | @item | |
2761 | The function @code{set-input-mode} now takes four arguments. The last | |
2762 | argument is optional. Their names are @var{interrupt}, @var{flow}, | |
2763 | @var{meta} and @var{quit}. | |
2764 | ||
2765 | The argument @var{interrupt} says whether to use interrupt-driven | |
2766 | input. Non-@code{nil} means yes, and @code{nil} means no (use CBREAK | |
2767 | mode). | |
2768 | ||
2769 | The argument @var{flow} says whether to enable terminal flow control. | |
2770 | Non-@code{nil} means yes. | |
2771 | ||
2772 | The argument @var{meta} says whether to enable the use of a Meta key. | |
2773 | Non-@code{nil} means yes. | |
2774 | ||
2775 | If @var{quit} non-@code{nil}, it is the character to use for quitting. | |
2776 | (Normally this is @kbd{C-g}.) | |
2777 | ||
2778 | @item | |
2779 | The variable @code{meta-flag} has been deleted; use | |
2780 | @code{set-input-mode} to enable or disable support for a @key{META} | |
2781 | key. This change was made because @code{set-input-mode} can send the | |
2782 | terminal the appropriate commands to enable or disable operation of the | |
2783 | @key{META} key. | |
2784 | ||
2785 | @item | |
2786 | The new variable @code{extra-keyboard-modifiers} lets Lisp programs | |
2787 | ``press'' the modifier keys on the keyboard. | |
2788 | The value is a bit mask: | |
2789 | ||
2790 | @table @asis | |
2791 | @item 1 | |
2792 | The @key{SHIFT} key. | |
2793 | @item 2 | |
2794 | The @key{LOCK} key. | |
2795 | @item 4 | |
2796 | The @key{CTL} key. | |
2797 | @item 8 | |
2798 | The @key{META} key. | |
2799 | @end table | |
2800 | ||
2801 | When you use X windows, the program can press any of the modifier keys | |
2802 | in this way. Otherwise, only the @key{CTL} and @key{META} keys can be | |
2803 | virtually pressed. | |
2804 | ||
2805 | @item | |
2806 | You can use the new function @code{keyboard-translate} to set up | |
2807 | @code{keyboard-translate-table} conveniently. | |
2808 | ||
2809 | @item | |
2810 | Y-or-n questions using the @code{y-or-n-p} function now accept @kbd{C-]} | |
2811 | (usually mapped to @code{abort-recursive-edit}) as well as @kbd{C-g} to | |
2812 | quit. | |
2813 | ||
2814 | @item | |
2815 | The variable @code{num-input-keys} is the total number of key sequences | |
2816 | that the user has typed during this Emacs session. | |
2817 | ||
2818 | @item | |
2819 | A new Lisp variable, @code{function-key-map}, holds a keymap which | |
2820 | describes the character sequences sent by function keys on an ordinary | |
2821 | character terminal. This uses the same keymap data structure that is | |
2822 | used to hold bindings of key sequences, but it has a different meaning: | |
2823 | it specifies translations to make while reading a key sequence. | |
2824 | ||
2825 | If @code{function-key-map} ``binds'' a key sequence @var{k} to a vector | |
2826 | @var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a | |
2827 | key sequence, it is replaced with @var{v}. | |
2828 | ||
2829 | For example, VT100 terminals send @kbd{@key{ESC} O P} when the ``keypad'' | |
2830 | PF1 key is pressed. Thus, on a VT100, @code{function-key-map} should | |
2831 | ``bind'' that sequence to @code{[pf1]}. This specifies translation of | |
2832 | @kbd{@key{ESC} O P} into @key{PF1} anywhere in a key sequence. | |
2833 | ||
2834 | Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c | |
2835 | @key{ESC} O P}, but @code{read-key-sequence} translates this back into | |
2836 | @kbd{C-c @key{PF1}}, which it returns as the vector @code{[?\C-c PF1]}. | |
2837 | ||
2838 | Entries in @code{function-key-map} are ignored if they conflict with | |
2839 | bindings made in the minor mode, local, or global keymaps. | |
2840 | ||
2841 | The value of @code{function-key-map} is usually set up automatically | |
2842 | according to the terminal's Terminfo or Termcap entry, and the | |
2843 | terminal-specific Lisp files. Emacs comes with a number of | |
2844 | terminal-specific files for many common terminals; their main purpose is | |
2845 | to make entries in @code{function-key-map} beyond those that can be | |
2846 | deduced from Termcap and Terminfo. | |
2847 | ||
2848 | @item | |
2849 | The variable @code{key-translation-map} works like @code{function-key-map} | |
2850 | except for two things: | |
2851 | ||
2852 | @itemize @bullet | |
2853 | @item | |
2854 | @code{key-translation-map} goes to work after @code{function-key-map} is | |
2855 | finished; it receives the results of translation by | |
2856 | @code{function-key-map}. | |
2857 | ||
2858 | @item | |
2859 | @code{key-translation-map} overrides actual key bindings. | |
2860 | @end itemize | |
2861 | ||
2862 | The intent of @code{key-translation-map} is for users to map one | |
2863 | character set to another, including ordinary characters normally bound | |
2864 | to @code{self-insert-command}. | |
2865 | @end itemize | |
2866 | ||
2867 | @section New Syntax Table Features | |
2868 | ||
2869 | @itemize @bullet | |
2870 | @item | |
2871 | You can use two new functions to move across characters in certain | |
2872 | syntax classes. | |
2873 | ||
2874 | @code{skip-syntax-forward} moves point forward across characters whose | |
2875 | syntax classes are mentioned in its first argument, a string. It stops | |
2876 | when it encounters the end of the buffer, or position @var{lim} (the | |
2877 | optional second argument), or a character it is not supposed to skip. | |
2878 | The function @code{skip-syntax-backward} is similar but moves backward. | |
2879 | ||
2880 | @item | |
2881 | The new function @code{forward-comment} moves point by comments. It | |
2882 | takes one argument, @var{count}; it moves point forward across | |
2883 | @var{count} comments (backward, if @var{count} is negative). If it | |
2884 | finds anything other than a comment or whitespace, it stops, leaving | |
2885 | point at the far side of the last comment found. It also stops after | |
2886 | satisfying @var{count}. | |
2887 | ||
2888 | @item | |
2889 | The new variable @code{words-include-escapes} affects the behavior of | |
2890 | @code{forward-word} and everything that uses it. If it is | |
2891 | non-@code{nil}, then characters in the ``escape'' and ``character | |
2892 | quote'' syntax classes count as part of words. | |
2893 | ||
2894 | @item | |
2895 | There are two new syntax flags for use in syntax tables. | |
2896 | ||
2897 | @itemize - | |
2898 | @item | |
2899 | The prefix flag. | |
2900 | ||
2901 | The @samp{p} flag identifies additional ``prefix characters'' in Lisp | |
2902 | syntax. You can set this flag with @code{modify-syntax-entry} by | |
2903 | including the letter @samp{p} in the syntax specification. | |
2904 | ||
2905 | These characters are treated as whitespace when they appear between | |
2906 | expressions. When they appear withing an expression, they are handled | |
2907 | according to their usual syntax codes. | |
2908 | ||
2909 | The function @code{backward-prefix-chars} moves back over these | |
2910 | characters, as well as over characters whose primary syntax class is | |
2911 | prefix (@samp{'}). | |
2912 | ||
2913 | @item | |
2914 | The @samp{b} comment style flag. | |
2915 | ||
2916 | Emacs can now supports two comment styles simultaneously. (This is for | |
2917 | the sake of C++.) More specifically, it can recognize two different | |
2918 | comment-start sequences. Both must share the same first character; only | |
2919 | the second character may differ. Mark the second character of the | |
2920 | @samp{b}-style comment start sequence with the @samp{b} flag. You can | |
2921 | set this flag with @code{modify-syntax-entry} by including the letter | |
2922 | @samp{b} in the syntax specification. | |
2923 | ||
2924 | The two styles of comment can have different comment-end sequences. A | |
2925 | comment-end sequence (one or two characters) applies to the @samp{b} | |
2926 | style if its first character has the @samp{b} flag set; otherwise, it | |
2927 | applies to the @samp{a} style. | |
2928 | ||
2929 | The appropriate comment syntax settings for C++ are as follows: | |
2930 | ||
2931 | @table @asis | |
2932 | @item @samp{/} | |
2933 | @samp{124b} | |
2934 | @item @samp{*} | |
2935 | @samp{23} | |
2936 | @item newline | |
2937 | @samp{>b} | |
2938 | @end table | |
2939 | ||
2940 | Thus @samp{/*} is a comment-start sequence for @samp{a} style, @samp{//} | |
2941 | is a comment-start sequence for @samp{b} style, @samp{*/} is a | |
2942 | comment-end sequence for @samp{a} style, and newline is a comment-end | |
2943 | sequence for @samp{b} style. | |
2944 | @end itemize | |
2945 | @end itemize | |
2946 | ||
2947 | @section The Case Table | |
2948 | ||
2949 | You can customize case conversion using the new case table feature. A | |
2950 | case table is a collection of strings that specifies the mapping between | |
2951 | upper case and lower case letters. Each buffer has its own case table. | |
2952 | You need a case table if you are using a language which has letters that | |
2953 | are not standard ASCII letters. | |
2954 | ||
2955 | A case table is a list of this form: | |
2956 | ||
2957 | @example | |
2958 | (@var{downcase} @var{upcase} @var{canonicalize} @var{equivalences}) | |
2959 | @end example | |
2960 | ||
2961 | @noindent | |
2962 | where each element is either @code{nil} or a string of length 256. The | |
2963 | element @var{downcase} says how to map each character to its lower-case | |
2964 | equivalent. The element @var{upcase} maps each character to its | |
2965 | upper-case equivalent. If lower and upper case characters are in 1-1 | |
2966 | correspondence, use @code{nil} for @var{upcase}; then Emacs deduces the | |
2967 | upcase table from @var{downcase}. | |
2968 | ||
2969 | For some languages, upper and lower case letters are not in 1-1 | |
2970 | correspondence. There may be two different lower case letters with the | |
2971 | same upper case equivalent. In these cases, you need to specify the | |
2972 | maps for both directions. | |
2973 | ||
2974 | The element @var{canonicalize} maps each character to a canonical | |
2975 | equivalent; any two characters that are related by case-conversion have | |
2976 | the same canonical equivalent character. | |
2977 | ||
2978 | The element @var{equivalences} is a map that cyclicly permutes each | |
2979 | equivalence class (of characters with the same canonical equivalent). | |
2980 | ||
2981 | You can provide @code{nil} for both @var{canonicalize} and | |
2982 | @var{equivalences}, in which case both are deduced from @var{downcase} | |
2983 | and @var{upcase}. | |
2984 | ||
2985 | Here are the functions for working with case tables: | |
2986 | ||
2987 | @code{case-table-p} is a predicate that says whether a Lisp object is a | |
2988 | valid case table. | |
2989 | ||
2990 | @code{set-standard-case-table} takes one argument and makes that | |
2991 | argument the case table for new buffers created subsequently. | |
2992 | @code{standard-case-table} returns the current value of the new buffer | |
2993 | case table. | |
2994 | ||
2995 | @code{current-case-table} returns the case table of the current buffer. | |
2996 | @code{set-case-table} sets the current buffer's case table to the | |
2997 | argument. | |
2998 | ||
2999 | @code{set-case-syntax-pair} is a convenient function for specifying a | |
3000 | pair of letters, upper case and lower case. Call it with two arguments, | |
3001 | the upper case letter and the lower case letter. It modifies the | |
3002 | standard case table and a few syntax tables that are predefined in | |
3003 | Emacs. This function is intended as a subroutine for packages that | |
3004 | define non-ASCII character sets. | |
3005 | ||
3006 | Load the library @file{iso-syntax} to set up the syntax and case table for | |
3007 | the 256 bit ISO Latin 1 character set. | |
3008 | ||
3009 | @section New Features for Dealing with Buffers | |
3010 | ||
3011 | @itemize @bullet | |
3012 | @item | |
3013 | The new function @code{buffer-modified-tick} returns a buffer's | |
3014 | modification-count that ticks every time the buffer is modified. It | |
3015 | takes one optional argument, which is the buffer you want to examine. | |
3016 | If the argument is @code{nil} (or omitted), the current buffer is used. | |
3017 | ||
3018 | @item | |
3019 | @code{buffer-disable-undo} is a new name for the function | |
3020 | formerly known as @code{buffer-flush-undo}. This turns off recording | |
3021 | of undo information in the buffer given as argument. | |
3022 | ||
3023 | @item | |
3024 | The new function @code{generate-new-buffer-name} chooses a name that | |
3025 | would be unique for a new buffer---but does not create the buffer. Give | |
3026 | it one argument, a starting name. It produces a name not in use for a | |
3027 | buffer by appending a number inside of @samp{<@dots{}>}. | |
3028 | ||
3029 | @item | |
3030 | The function @code{rename-buffer} now takes an option second argument | |
3031 | which tells it that if the specified new name corresponds to an existing | |
3032 | buffer, it should use @code{generate-new-buffer-name} to modify the name | |
3033 | to be unique, rather than signaling an error. | |
3034 | ||
3035 | @code{rename-buffer} now returns the name to which the buffer was | |
3036 | renamed. | |
3037 | ||
3038 | @item | |
3039 | The function @code{list-buffers} now looks at the local variable | |
3040 | @code{list-buffers-directory} in each non-file-visiting buffer, and | |
3041 | shows its value where the file would normally go. Dired sets this | |
3042 | variable in each Dired buffer, so the buffer list now shows which | |
3043 | directory each Dired buffer is editing. | |
3044 | ||
3045 | @item | |
3046 | The function @code{other-buffer} now takes an optional second argument | |
3047 | @var{visible-ok} which, if non-@code{nil}, indicates that buffers | |
3048 | currently being displayed in windows may be returned even if there are | |
3049 | other buffers not visible. Normally, @code{other-buffer} returns a | |
3050 | currently visible buffer only as a last resort, if there are no suitable | |
3051 | nonvisible buffers. | |
3052 | ||
3053 | @item | |
3054 | The hook @code{kill-buffer-hook} now runs whenever a buffer is killed. | |
3055 | @end itemize | |
3056 | ||
3057 | @section Local Variables Features | |
3058 | ||
3059 | @itemize @bullet | |
3060 | @item | |
3061 | If a local variable name has a non-@code{nil} @code{permanent-local} | |
3062 | property, then @code{kill-all-local-variables} does not kill it. Such | |
3063 | local variables are ``permanent''---they remain unchanged even if you | |
3064 | select a different major mode. | |
3065 | ||
3066 | Permanent locals are useful when they have to do with where the file | |
3067 | came from or how to save it, rather than with how to edit the contents. | |
3068 | ||
3069 | @item | |
3070 | The function @code{make-local-variable} now never changes the value of the variable | |
3071 | that it makes local. If the variable had no value before, it still has | |
3072 | no value after becoming local. | |
3073 | ||
3074 | @item | |
3075 | The new function @code{default-boundp} tells you whether a variable has | |
3076 | a default value (as opposed to being unbound in its default value). If | |
3077 | @code{(default-boundp 'foo)} returns @code{nil}, then | |
3078 | @code{(default-value 'foo)} would get an error. | |
3079 | ||
3080 | @code{default-boundp} is to @code{default-value} as @code{boundp} is to | |
3081 | @code{symbol-value}. | |
3082 | ||
3083 | @item | |
3084 | The special forms @code{defconst} and @code{defvar}, when the variable | |
3085 | is local in the current buffer, now set the variable's default value | |
3086 | rather than its local value. | |
3087 | @end itemize | |
3088 | ||
3089 | @section New Features for Subprocesses | |
3090 | ||
3091 | @itemize @bullet | |
3092 | @item | |
3093 | @code{call-process} and @code{call-process-region} now return a value | |
3094 | that indicates how the synchronous subprocess terminated. It is either | |
3095 | a number, which is the exit status of a process, or a signal name | |
3096 | represented as a string. | |
3097 | ||
3098 | @item | |
3099 | @code{process-status} now returns @code{open} and @code{closed} as the | |
3100 | status values for network connections. | |
3101 | ||
3102 | @item | |
3103 | The standard asynchronous subprocess features work on VMS now, | |
3104 | and the special VMS asynchronous subprocess functions have been deleted. | |
3105 | ||
3106 | @item | |
3107 | You can use the transaction queue feature for more convenient | |
3108 | communication with subprocesses using transactions. | |
3109 | ||
3110 | Call @code{tq-create} to create a transaction queue communicating with a | |
3111 | specified process. Then you can call @code{tq-enqueue} to send a | |
3112 | transaction. @code{tq-enqueue} takes these five arguments: | |
3113 | ||
3114 | @example | |
3115 | (tq-enqueue @var{tq} @var{question} @var{regexp} @var{closure} @var{fn}) | |
3116 | @end example | |
3117 | ||
3118 | @var{tq} is the queue to use. (Specifying the queue has the effect of | |
3119 | specifying the process to talk to.) The argument @var{question} is the | |
3120 | outgoing message which starts the transaction. The argument @var{fn} is | |
3121 | the function to call when the corresponding answer comes back; it is | |
3122 | called with two arguments: @var{closure}, and the answer received. | |
3123 | ||
3124 | The argument @var{regexp} is a regular expression to match the entire | |
3125 | answer; that's how @code{tq-enqueue} tells where the answer ends. | |
3126 | ||
3127 | Call @code{tq-close} to shut down a transaction queue and terminate its | |
3128 | subprocess. | |
3129 | ||
3130 | @item | |
3131 | The function @code{signal-process} sends a signal to process @var{pid}, | |
3132 | which need not be a child of Emacs. The second argument @var{signal} | |
3133 | specifies which signal to send; it should be an integer. | |
3134 | @end itemize | |
3135 | ||
3136 | @section New Features for Dealing with Times And Time Delays | |
3137 | ||
3138 | @itemize @bullet | |
3139 | @item | |
3140 | The new function @code{current-time} returns the system's time value as | |
3141 | a list of three integers: @code{(@var{high} @var{low} @var{microsec})}. | |
3142 | The integers @var{high} and @var{low} combine to give the number of | |
3143 | seconds since 0:00 January 1, 1970, which is @var{high} * 2**16 + | |
3144 | @var{low}. | |
3145 | ||
3146 | @var{microsec} gives the microseconds since the start of the current | |
3147 | second (or 0 for systems that return time only on the resolution of a | |
3148 | second). | |
3149 | ||
3150 | @item | |
3151 | The function @code{current-time-string} accepts an optional argument | |
3152 | @var{time-value}. If given, this specifies a time to format instead of | |
3153 | the current time. The argument should be a cons cell containing two | |
3154 | integers, or a list whose first two elements are integers. Thus, you | |
3155 | can use times obtained from @code{current-time} (see above) and from | |
3156 | @code{file-attributes}. | |
3157 | ||
3158 | @item | |
3159 | You can now find out the user's time zone using @code{current-time-zone}. | |
3160 | It takes no arguments, and returns a list of this form: | |
3161 | ||
3162 | @example | |
3163 | (@var{offset} @var{savings-flag} @var{standard} @var{savings}) | |
3164 | @end example | |
3165 | ||
3166 | @var{offset} is an integer specifying how many minutes east of Greenwich | |
3167 | the current time zone is located. A negative value means west of | |
3168 | Greenwich. Note that this describes the standard time; if daylight | |
3169 | savings time is in effect, it does not affect this value. | |
3170 | ||
3171 | @var{savings-flag} is non-@code{nil} iff daylight savings time or some other | |
3172 | sort of seasonal time adjustment is in effect. | |
3173 | ||
3174 | @var{standard} is a string giving the name of the time zone when no | |
3175 | seasonal time adjustment is in effect. | |
3176 | ||
3177 | @var{savings} is a string giving the name of the time zone when there is a | |
3178 | seasonal time adjustment in effect. | |
3179 | ||
3180 | If the user has specified a region that does not use a seasonal time | |
3181 | adjustment, @var{savings-flag} is always @code{nil}, and @var{standard} | |
3182 | and @var{savings} are equal. | |
3183 | ||
3184 | @item | |
3185 | @code{sit-for}, @code{sleep-for} now let you specify the time period in | |
3186 | milliseconds as well as in seconds. The first argument gives the number | |
3187 | of seconds, as before, and the optional second argument gives additional | |
3188 | milliseconds. The time periods specified by these two arguments are | |
3189 | added together. | |
3190 | ||
3191 | Not all systems support this; you get an error if you specify nonzero | |
3192 | milliseconds and it isn't supported. | |
3193 | ||
3194 | @code{sit-for} also accepts an optional third argument @var{nodisp}. If | |
3195 | this is non-@code{nil}, @code{sit-for} does not redisplay. It still | |
3196 | waits for the specified time or until input is available. | |
3197 | ||
3198 | @item | |
3199 | @code{accept-process-output} now accepts a timeout specified by optional | |
3200 | second and third arguments. The second argument specifies the number of | |
3201 | seconds, while the third specifies the number of milliseconds. The time | |
3202 | periods specified by these two arguments are added together. | |
3203 | ||
3204 | Not all systems support this; you get an error if you specify nonzero | |
3205 | milliseconds and it isn't supported. | |
3206 | ||
3207 | The function returns @code{nil} if the timeout expired before output | |
3208 | arrived, or non-@code{nil} if it did get some output. | |
3209 | ||
3210 | @item | |
3211 | You can set up a timer to call a function at a specified future time. | |
3212 | To do so, call @code{run-at-time}, like this: | |
3213 | ||
3214 | @example | |
3215 | (run-at-time @var{time} @var{repeat} @var{function} @var{args}@dots{}) | |
3216 | @end example | |
3217 | ||
3218 | Here, @var{time} is a string saying when to call the function. The | |
3219 | argument @var{function} is the function to call later, and @var{args} | |
3220 | are the arguments to give it when it is called. | |
3221 | ||
3222 | The argument @var{repeat} specifies how often to repeat the call. If | |
3223 | @var{repeat} is @code{nil}, there are no repetitions; @var{function} is | |
3224 | called just once, at @var{time}. If @var{repeat} is an integer, it | |
3225 | specifies a repetition period measured in seconds. | |
3226 | ||
3227 | Absolute times may be specified in a wide variety of formats; The form | |
3228 | @samp{@var{hour}:@var{min}:@var{sec} @var{timezone} | |
3229 | @var{month}/@var{day}/@var{year}}, where all fields are numbers, works; | |
3230 | the format that @code{current-time-string} returns is also allowed. | |
3231 | ||
3232 | To specify a relative time, use numbers followed by units. | |
3233 | For example: | |
3234 | ||
3235 | @table @samp | |
3236 | @item 1 min | |
3237 | denotes 1 minute from now. | |
3238 | @item 1 min 5 sec | |
3239 | denotes 65 seconds from now. | |
3240 | @item 1 min 2 sec 3 hour 4 day 5 week 6 fortnight 7 month 8 year | |
3241 | denotes exactly 103 months, 123 days, and 10862 seconds from now. | |
3242 | @end table | |
3243 | ||
3244 | If @var{time} is an integer, that specifies a relative time measured in | |
3245 | seconds. | |
3246 | @end itemize | |
3247 | ||
3248 | To cancel the requested future action, pass the value that @code{run-at-time} | |
3249 | returned to the function @code{cancel-timer}. | |
3250 | ||
3251 | @section Profiling Lisp Programs | |
3252 | ||
3253 | You can now make execution-time profiles of Emacs Lisp programs using | |
3254 | the @file{profile} library. See the file @file{profile.el} for | |
3255 | instructions; if you have written a Lisp program big enough to be worth | |
3256 | profiling, you can surely understand them. | |
3257 | ||
3258 | @section New Features for Lisp Debuggers | |
3259 | ||
3260 | @itemize @bullet | |
3261 | @item | |
3262 | You can now specify which kinds of errors should invoke the Lisp | |
3263 | debugger by setting the variable @code{debug-on-error} to a list of error | |
3264 | conditions. For example, if you set it to the list @code{(void-variable)}, | |
3265 | then only errors about a variable that has no value invoke the | |
3266 | debugger. | |
3267 | ||
3268 | @item | |
3269 | The variable @code{command-debug-status} is used by Lisp debuggers. It | |
3270 | records the debugging status of current interactive command. Each time | |
3271 | a command is called interactively, this variable is bound to | |
3272 | @code{nil}. The debugger can set this variable to leave information for | |
3273 | future debugger invocations during the same command. | |
3274 | ||
3275 | The advantage of this variable over some other variable in the debugger | |
3276 | itself is that the data will not be visible for any other command | |
3277 | invocation. | |
3278 | ||
3279 | @item | |
3280 | The function @code{backtrace-frame} is intended for use in Lisp | |
3281 | debuggers. It returns information about what a frame on the Lisp call | |
3282 | stack is doing. You specify one argument, which is the number of stack | |
3283 | frames to count up from the current execution point. | |
3284 | ||
3285 | If that stack frame has not evaluated the arguments yet (or is a special | |
3286 | form), the value is @code{(nil @var{function} @var{arg-forms}@dots{})}. | |
3287 | ||
3288 | If that stack frame has evaluated its arguments and called its function | |
3289 | already, the value is @code{(t @var{function} | |
3290 | @var{arg-values}@dots{})}. | |
3291 | ||
3292 | In the return value, @var{function} is whatever was supplied as @sc{car} | |
3293 | of evaluated list, or a @code{lambda} expression in the case of a macro | |
3294 | call. If the function has a @code{&rest} argument, that is represented | |
3295 | as the tail of the list @var{arg-values}. | |
3296 | ||
3297 | If the argument is out of range, @code{backtrace-frame} returns | |
3298 | @code{nil}. | |
3299 | @end itemize | |
3300 | ||
3301 | @ignore | |
3302 | ||
3303 | @item | |
3304 | @code{kill-ring-save} now gives visual feedback to indicate the region | |
3305 | of text being added to the kill ring. If the opposite end of the | |
3306 | region is visible in the current window, the cursor blinks there. | |
3307 | Otherwise, some text from the other end of the region is displayed in | |
3308 | the message area. | |
3309 | @end ignore | |
3310 | ||
3311 | @section Memory Allocation Changes | |
3312 | ||
3313 | The list that @code{garbage-collect} returns now has one additional | |
3314 | element. This is a cons cell containing two numbers. It gives | |
3315 | information about the number of used and free floating point numbers, | |
3316 | much as the first element gives such information about the number of | |
3317 | used and free cons cells. | |
3318 | ||
3319 | The new function @code{memory-limit} returns an indication of the last | |
3320 | address allocated by Emacs. More precisely, it returns that address | |
3321 | divided by 1024. You can use this to get a general idea of how your | |
3322 | actions affect the memory usage. | |
3323 | ||
3324 | @section Hook Changes | |
3325 | ||
3326 | @itemize @bullet | |
3327 | @item | |
3328 | Expanding an abbrev first runs the new hook | |
3329 | @code{pre-abbrev-expand-hook}. | |
3330 | ||
3331 | @item | |
3332 | The editor command loop runs the normal hook @code{pre-command-hook} | |
3333 | before each command, and runs @code{post-command-hook} after each | |
3334 | command. | |
3335 | ||
3336 | @item | |
3337 | Auto-saving runs the new hook @code{auto-save-hook} before actually | |
3338 | starting to save any files. | |
3339 | ||
3340 | @item | |
3341 | The new variable @code{revert-buffer-insert-file-contents-function} | |
3342 | holds a function that @code{revert-buffer} now uses to read in the | |
3343 | contents of the reverted buffer---instead of calling | |
3344 | @code{insert-file-contents}. | |
3345 | ||
3346 | @item | |
3347 | The variable @code{lisp-indent-hook} has been renamed to | |
3348 | @code{lisp-indent-function}. | |
3349 | ||
3350 | @item | |
3351 | The variable @code{auto-fill-hook} has been renamed to | |
3352 | @code{auto-fill-function}. | |
3353 | ||
3354 | @item | |
3355 | The variable @code{blink-paren-hook} has been renamed to | |
3356 | @code{blink-paren-function}. | |
3357 | ||
3358 | @item | |
3359 | The variable @code{temp-buffer-show-hook} has been renamed to | |
3360 | @code{temp-buffer-show-function}. | |
3361 | ||
3362 | @item | |
3363 | The variable @code{suspend-hook} has been renamed to | |
3364 | @code{suspend-hooks}, because it is a list of functions but is not a | |
3365 | normal hook. | |
3366 | ||
3367 | @item | |
3368 | The new function @code{add-hook} provides a handy way to add a function | |
3369 | to a hook variable. For example, | |
3370 | ||
3371 | @example | |
3372 | (add-hook 'text-mode-hook 'my-text-hook-function) | |
3373 | @end example | |
3374 | ||
3375 | @noindent | |
3376 | arranges to call @code{my-text-hook-function} | |
3377 | when entering Text mode or related modes. | |
3378 | @end itemize | |
3379 | ||
3380 | @bye |