| 1 | @c -*-texinfo-*- |
| 2 | @c This is part of the GNU Emacs Lisp Reference Manual. |
| 3 | @c Copyright (C) 1990-1995, 1998-1999, 2001-2012 |
| 4 | @c Free Software Foundation, Inc. |
| 5 | @c See the file elisp.texi for copying conditions. |
| 6 | @node Minibuffers, Command Loop, Read and Print, Top |
| 7 | @chapter Minibuffers |
| 8 | @cindex arguments, reading |
| 9 | @cindex complex arguments |
| 10 | @cindex minibuffer |
| 11 | |
| 12 | A @dfn{minibuffer} is a special buffer that Emacs commands use to |
| 13 | read arguments more complicated than the single numeric prefix |
| 14 | argument. These arguments include file names, buffer names, and |
| 15 | command names (as in @kbd{M-x}). The minibuffer is displayed on the |
| 16 | bottom line of the frame, in the same place as the echo area |
| 17 | (@pxref{The Echo Area}), but only while it is in use for reading an |
| 18 | argument. |
| 19 | |
| 20 | @menu |
| 21 | * Intro to Minibuffers:: Basic information about minibuffers. |
| 22 | * Text from Minibuffer:: How to read a straight text string. |
| 23 | * Object from Minibuffer:: How to read a Lisp object or expression. |
| 24 | * Minibuffer History:: Recording previous minibuffer inputs |
| 25 | so the user can reuse them. |
| 26 | * Initial Input:: Specifying initial contents for the minibuffer. |
| 27 | * Completion:: How to invoke and customize completion. |
| 28 | * Yes-or-No Queries:: Asking a question with a simple answer. |
| 29 | * Multiple Queries:: Asking a series of similar questions. |
| 30 | * Reading a Password:: Reading a password from the terminal. |
| 31 | * Minibuffer Commands:: Commands used as key bindings in minibuffers. |
| 32 | * Minibuffer Windows:: Operating on the special minibuffer windows. |
| 33 | * Minibuffer Contents:: How such commands access the minibuffer text. |
| 34 | * Recursive Mini:: Whether recursive entry to minibuffer is allowed. |
| 35 | * Minibuffer Misc:: Various customization hooks and variables. |
| 36 | @end menu |
| 37 | |
| 38 | @node Intro to Minibuffers |
| 39 | @section Introduction to Minibuffers |
| 40 | |
| 41 | In most ways, a minibuffer is a normal Emacs buffer. Most operations |
| 42 | @emph{within} a buffer, such as editing commands, work normally in a |
| 43 | minibuffer. However, many operations for managing buffers do not apply |
| 44 | to minibuffers. The name of a minibuffer always has the form @w{@samp{ |
| 45 | *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are |
| 46 | displayed only in special windows used only for minibuffers; these |
| 47 | windows always appear at the bottom of a frame. (Sometimes frames have |
| 48 | no minibuffer window, and sometimes a special kind of frame contains |
| 49 | nothing but a minibuffer window; see @ref{Minibuffers and Frames}.) |
| 50 | |
| 51 | The text in the minibuffer always starts with the @dfn{prompt string}, |
| 52 | the text that was specified by the program that is using the minibuffer |
| 53 | to tell the user what sort of input to type. This text is marked |
| 54 | read-only so you won't accidentally delete or change it. It is also |
| 55 | marked as a field (@pxref{Fields}), so that certain motion functions, |
| 56 | including @code{beginning-of-line}, @code{forward-word}, |
| 57 | @code{forward-sentence}, and @code{forward-paragraph}, stop at the |
| 58 | boundary between the prompt and the actual text. |
| 59 | |
| 60 | @c See http://debbugs.gnu.org/11276 |
| 61 | The minibuffer's window is normally a single line; it grows |
| 62 | automatically if the contents require more space. Whilst it is |
| 63 | active, you can explicitly resize it temporarily with the window |
| 64 | sizing commands; it reverts to its normal size when the minibuffer is |
| 65 | exited. When the minibuffer is not active, you can resize it |
| 66 | permanently by using the window sizing commands in the frame's other |
| 67 | window, or dragging the mode line with the mouse. (Due to details of |
| 68 | the current implementation, for this to work @code{resize-mini-windows} |
| 69 | must be @code{nil}.) If the frame contains just a minibuffer, you can |
| 70 | change the minibuffer's size by changing the frame's size. |
| 71 | |
| 72 | Use of the minibuffer reads input events, and that alters the values |
| 73 | of variables such as @code{this-command} and @code{last-command} |
| 74 | (@pxref{Command Loop Info}). Your program should bind them around the |
| 75 | code that uses the minibuffer, if you do not want that to change them. |
| 76 | |
| 77 | Under some circumstances, a command can use a minibuffer even if |
| 78 | there is an active minibuffer; such a minibuffer is called a |
| 79 | @dfn{recursive minibuffer}. The first minibuffer is named |
| 80 | @w{@samp{ *Minibuf-1*}}. Recursive minibuffers are named by |
| 81 | incrementing the number at the end of the name. (The names begin with |
| 82 | a space so that they won't show up in normal buffer lists.) Of |
| 83 | several recursive minibuffers, the innermost (or most recently |
| 84 | entered) is the active minibuffer. We usually call this ``the'' |
| 85 | minibuffer. You can permit or forbid recursive minibuffers by setting |
| 86 | the variable @code{enable-recursive-minibuffers}, or by putting |
| 87 | properties of that name on command symbols (@xref{Recursive Mini}.) |
| 88 | |
| 89 | Like other buffers, a minibuffer uses a local keymap |
| 90 | (@pxref{Keymaps}) to specify special key bindings. The function that |
| 91 | invokes the minibuffer also sets up its local map according to the job |
| 92 | to be done. @xref{Text from Minibuffer}, for the non-completion |
| 93 | minibuffer local maps. @xref{Completion Commands}, for the minibuffer |
| 94 | local maps for completion. |
| 95 | |
| 96 | @cindex inactive minibuffer |
| 97 | When a minibuffer is inactive, its major mode is |
| 98 | @code{minibuffer-inactive-mode}, with keymap |
| 99 | @code{minibuffer-inactive-mode-map}. This is only really useful if |
| 100 | the minibuffer is in a separate frame. @xref{Minibuffers and Frames}. |
| 101 | |
| 102 | When Emacs is running in batch mode, any request to read from the |
| 103 | minibuffer actually reads a line from the standard input descriptor that |
| 104 | was supplied when Emacs was started. |
| 105 | |
| 106 | @node Text from Minibuffer |
| 107 | @section Reading Text Strings with the Minibuffer |
| 108 | |
| 109 | The most basic primitive for minibuffer input is |
| 110 | @code{read-from-minibuffer}, which can be used to read either a string |
| 111 | or a Lisp object in textual form. The function @code{read-regexp} is |
| 112 | used for reading regular expressions (@pxref{Regular Expressions}), |
| 113 | which are a special kind of string. There are also specialized |
| 114 | functions for reading commands, variables, file names, etc.@: |
| 115 | (@pxref{Completion}). |
| 116 | |
| 117 | In most cases, you should not call minibuffer input functions in the |
| 118 | middle of a Lisp function. Instead, do all minibuffer input as part of |
| 119 | reading the arguments for a command, in the @code{interactive} |
| 120 | specification. @xref{Defining Commands}. |
| 121 | |
| 122 | @defun read-from-minibuffer prompt &optional initial keymap read history default inherit-input-method |
| 123 | This function is the most general way to get input from the |
| 124 | minibuffer. By default, it accepts arbitrary text and returns it as a |
| 125 | string; however, if @var{read} is non-@code{nil}, then it uses |
| 126 | @code{read} to convert the text into a Lisp object (@pxref{Input |
| 127 | Functions}). |
| 128 | |
| 129 | The first thing this function does is to activate a minibuffer and |
| 130 | display it with @var{prompt} (which must be a string) as the |
| 131 | prompt. Then the user can edit text in the minibuffer. |
| 132 | |
| 133 | When the user types a command to exit the minibuffer, |
| 134 | @code{read-from-minibuffer} constructs the return value from the text in |
| 135 | the minibuffer. Normally it returns a string containing that text. |
| 136 | However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer} |
| 137 | reads the text and returns the resulting Lisp object, unevaluated. |
| 138 | (@xref{Input Functions}, for information about reading.) |
| 139 | |
| 140 | The argument @var{default} specifies default values to make available |
| 141 | through the history commands. It should be a string, a list of |
| 142 | strings, or @code{nil}. The string or strings become the minibuffer's |
| 143 | ``future history'', available to the user with @kbd{M-n}. |
| 144 | |
| 145 | If @var{read} is non-@code{nil}, then @var{default} is also used |
| 146 | as the input to @code{read}, if the user enters empty input. |
| 147 | If @var{default} is a list of strings, the first string is used as the input. |
| 148 | If @var{default} is @code{nil}, empty input results in an @code{end-of-file} error. |
| 149 | However, in the usual case (where @var{read} is @code{nil}), |
| 150 | @code{read-from-minibuffer} ignores @var{default} when the user enters |
| 151 | empty input and returns an empty string, @code{""}. In this respect, |
| 152 | it differs from all the other minibuffer input functions in this chapter. |
| 153 | |
| 154 | If @var{keymap} is non-@code{nil}, that keymap is the local keymap to |
| 155 | use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the |
| 156 | value of @code{minibuffer-local-map} is used as the keymap. Specifying |
| 157 | a keymap is the most important way to customize the minibuffer for |
| 158 | various applications such as completion. |
| 159 | |
| 160 | The argument @var{history} specifies a history list variable to use |
| 161 | for saving the input and for history commands used in the minibuffer. |
| 162 | It defaults to @code{minibuffer-history}. You can optionally specify |
| 163 | a starting position in the history list as well. @xref{Minibuffer History}. |
| 164 | |
| 165 | If the variable @code{minibuffer-allow-text-properties} is |
| 166 | non-@code{nil}, then the string that is returned includes whatever text |
| 167 | properties were present in the minibuffer. Otherwise all the text |
| 168 | properties are stripped when the value is returned. |
| 169 | |
| 170 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
| 171 | minibuffer inherits the current input method (@pxref{Input Methods}) and |
| 172 | the setting of @code{enable-multibyte-characters} (@pxref{Text |
| 173 | Representations}) from whichever buffer was current before entering the |
| 174 | minibuffer. |
| 175 | |
| 176 | Use of @var{initial} is mostly deprecated; we recommend using |
| 177 | a non-@code{nil} value only in conjunction with specifying a cons cell |
| 178 | for @var{history}. @xref{Initial Input}. |
| 179 | @end defun |
| 180 | |
| 181 | @defun read-string prompt &optional initial history default inherit-input-method |
| 182 | This function reads a string from the minibuffer and returns it. The |
| 183 | arguments @var{prompt}, @var{initial}, @var{history} and |
| 184 | @var{inherit-input-method} are used as in @code{read-from-minibuffer}. |
| 185 | The keymap used is @code{minibuffer-local-map}. |
| 186 | |
| 187 | The optional argument @var{default} is used as in |
| 188 | @code{read-from-minibuffer}, except that, if non-@code{nil}, it also |
| 189 | specifies a default value to return if the user enters null input. As |
| 190 | in @code{read-from-minibuffer} it should be a string, a list of |
| 191 | strings, or @code{nil}, which is equivalent to an empty string. When |
| 192 | @var{default} is a string, that string is the default value. When it |
| 193 | is a list of strings, the first string is the default value. (All |
| 194 | these strings are available to the user in the ``future minibuffer |
| 195 | history''.) |
| 196 | |
| 197 | This function works by calling the |
| 198 | @code{read-from-minibuffer} function: |
| 199 | |
| 200 | @smallexample |
| 201 | @group |
| 202 | (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit}) |
| 203 | @equiv{} |
| 204 | (let ((value |
| 205 | (read-from-minibuffer @var{prompt} @var{initial} nil nil |
| 206 | @var{history} @var{default} @var{inherit}))) |
| 207 | (if (and (equal value "") @var{default}) |
| 208 | (if (consp @var{default}) (car @var{default}) @var{default}) |
| 209 | value)) |
| 210 | @end group |
| 211 | @end smallexample |
| 212 | @end defun |
| 213 | |
| 214 | @defun read-regexp prompt &optional default |
| 215 | This function reads a regular expression as a string from the |
| 216 | minibuffer and returns it. The argument @var{prompt} is used as in |
| 217 | @code{read-from-minibuffer}. The keymap used is |
| 218 | @code{minibuffer-local-map}, and @code{regexp-history} is used as the |
| 219 | history list (@pxref{Minibuffer History, regexp-history}). |
| 220 | |
| 221 | The optional argument @var{default} specifies a default value to |
| 222 | return if the user enters null input; it should be a string, or |
| 223 | @code{nil}, which is equivalent to an empty string. |
| 224 | |
| 225 | In addition, @code{read-regexp} collects a few useful candidates for |
| 226 | input and passes them to @code{read-from-minibuffer}, to make them |
| 227 | available to the user as the ``future minibuffer history list'' |
| 228 | (@pxref{Minibuffer History, future list,, emacs, The GNU Emacs |
| 229 | Manual}). These candidates are: |
| 230 | |
| 231 | @itemize @minus |
| 232 | @item |
| 233 | The word or symbol at point. |
| 234 | @item |
| 235 | The last regexp used in an incremental search. |
| 236 | @item |
| 237 | The last string used in an incremental search. |
| 238 | @item |
| 239 | The last string or pattern used in query-replace commands. |
| 240 | @end itemize |
| 241 | |
| 242 | This function works by calling the @code{read-from-minibuffer} |
| 243 | function, after computing the list of defaults as described above. |
| 244 | @end defun |
| 245 | |
| 246 | @defvar minibuffer-allow-text-properties |
| 247 | If this variable is @code{nil}, then @code{read-from-minibuffer} |
| 248 | and @code{read-string} strip all text properties from the minibuffer |
| 249 | input before returning it. However, |
| 250 | @code{read-no-blanks-input} (see below), as well as |
| 251 | @code{read-minibuffer} and related functions (@pxref{Object from |
| 252 | Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all |
| 253 | functions that do minibuffer input with completion, discard text |
| 254 | properties unconditionally, regardless of the value of this variable. |
| 255 | @end defvar |
| 256 | |
| 257 | @defvar minibuffer-local-map |
| 258 | This |
| 259 | @anchor{Definition of minibuffer-local-map} |
| 260 | @c avoid page break at anchor; work around Texinfo deficiency |
| 261 | is the default local keymap for reading from the minibuffer. By |
| 262 | default, it makes the following bindings: |
| 263 | |
| 264 | @table @asis |
| 265 | @item @kbd{C-j} |
| 266 | @code{exit-minibuffer} |
| 267 | |
| 268 | @item @key{RET} |
| 269 | @code{exit-minibuffer} |
| 270 | |
| 271 | @item @kbd{C-g} |
| 272 | @code{abort-recursive-edit} |
| 273 | |
| 274 | @item @kbd{M-n} |
| 275 | @itemx @key{DOWN} |
| 276 | @code{next-history-element} |
| 277 | |
| 278 | @item @kbd{M-p} |
| 279 | @itemx @key{UP} |
| 280 | @code{previous-history-element} |
| 281 | |
| 282 | @item @kbd{M-s} |
| 283 | @code{next-matching-history-element} |
| 284 | |
| 285 | @item @kbd{M-r} |
| 286 | @code{previous-matching-history-element} |
| 287 | |
| 288 | @ignore |
| 289 | @c Does not seem worth/appropriate mentioning. |
| 290 | @item @kbd{C-@key{TAB}} |
| 291 | @code{file-cache-minibuffer-complete} |
| 292 | @end ignore |
| 293 | @end table |
| 294 | @end defvar |
| 295 | |
| 296 | @c In version 18, initial is required |
| 297 | @c Emacs 19 feature |
| 298 | @defun read-no-blanks-input prompt &optional initial inherit-input-method |
| 299 | This function reads a string from the minibuffer, but does not allow |
| 300 | whitespace characters as part of the input: instead, those characters |
| 301 | terminate the input. The arguments @var{prompt}, @var{initial}, and |
| 302 | @var{inherit-input-method} are used as in @code{read-from-minibuffer}. |
| 303 | |
| 304 | This is a simplified interface to the @code{read-from-minibuffer} |
| 305 | function, and passes the value of the @code{minibuffer-local-ns-map} |
| 306 | keymap as the @var{keymap} argument for that function. Since the keymap |
| 307 | @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is} |
| 308 | possible to put a space into the string, by quoting it. |
| 309 | |
| 310 | This function discards text properties, regardless of the value of |
| 311 | @code{minibuffer-allow-text-properties}. |
| 312 | |
| 313 | @smallexample |
| 314 | @group |
| 315 | (read-no-blanks-input @var{prompt} @var{initial}) |
| 316 | @equiv{} |
| 317 | (let (minibuffer-allow-text-properties) |
| 318 | (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map)) |
| 319 | @end group |
| 320 | @end smallexample |
| 321 | @end defun |
| 322 | |
| 323 | @c Slightly unfortunate name, suggesting it might be related to the |
| 324 | @c Nextstep port... |
| 325 | @defvar minibuffer-local-ns-map |
| 326 | This built-in variable is the keymap used as the minibuffer local keymap |
| 327 | in the function @code{read-no-blanks-input}. By default, it makes the |
| 328 | following bindings, in addition to those of @code{minibuffer-local-map}: |
| 329 | |
| 330 | @table @asis |
| 331 | @item @key{SPC} |
| 332 | @cindex @key{SPC} in minibuffer |
| 333 | @code{exit-minibuffer} |
| 334 | |
| 335 | @item @key{TAB} |
| 336 | @cindex @key{TAB} in minibuffer |
| 337 | @code{exit-minibuffer} |
| 338 | |
| 339 | @item @kbd{?} |
| 340 | @cindex @kbd{?} in minibuffer |
| 341 | @code{self-insert-and-exit} |
| 342 | @end table |
| 343 | @end defvar |
| 344 | |
| 345 | @node Object from Minibuffer |
| 346 | @section Reading Lisp Objects with the Minibuffer |
| 347 | |
| 348 | This section describes functions for reading Lisp objects with the |
| 349 | minibuffer. |
| 350 | |
| 351 | @defun read-minibuffer prompt &optional initial |
| 352 | This function reads a Lisp object using the minibuffer, and returns it |
| 353 | without evaluating it. The arguments @var{prompt} and @var{initial} are |
| 354 | used as in @code{read-from-minibuffer}. |
| 355 | |
| 356 | This is a simplified interface to the |
| 357 | @code{read-from-minibuffer} function: |
| 358 | |
| 359 | @smallexample |
| 360 | @group |
| 361 | (read-minibuffer @var{prompt} @var{initial}) |
| 362 | @equiv{} |
| 363 | (let (minibuffer-allow-text-properties) |
| 364 | (read-from-minibuffer @var{prompt} @var{initial} nil t)) |
| 365 | @end group |
| 366 | @end smallexample |
| 367 | |
| 368 | Here is an example in which we supply the string @code{"(testing)"} as |
| 369 | initial input: |
| 370 | |
| 371 | @smallexample |
| 372 | @group |
| 373 | (read-minibuffer |
| 374 | "Enter an expression: " (format "%s" '(testing))) |
| 375 | |
| 376 | ;; @r{Here is how the minibuffer is displayed:} |
| 377 | @end group |
| 378 | |
| 379 | @group |
| 380 | ---------- Buffer: Minibuffer ---------- |
| 381 | Enter an expression: (testing)@point{} |
| 382 | ---------- Buffer: Minibuffer ---------- |
| 383 | @end group |
| 384 | @end smallexample |
| 385 | |
| 386 | @noindent |
| 387 | The user can type @key{RET} immediately to use the initial input as a |
| 388 | default, or can edit the input. |
| 389 | @end defun |
| 390 | |
| 391 | @defun eval-minibuffer prompt &optional initial |
| 392 | This function reads a Lisp expression using the minibuffer, evaluates |
| 393 | it, then returns the result. The arguments @var{prompt} and |
| 394 | @var{initial} are used as in @code{read-from-minibuffer}. |
| 395 | |
| 396 | This function simply evaluates the result of a call to |
| 397 | @code{read-minibuffer}: |
| 398 | |
| 399 | @smallexample |
| 400 | @group |
| 401 | (eval-minibuffer @var{prompt} @var{initial}) |
| 402 | @equiv{} |
| 403 | (eval (read-minibuffer @var{prompt} @var{initial})) |
| 404 | @end group |
| 405 | @end smallexample |
| 406 | @end defun |
| 407 | |
| 408 | @defun edit-and-eval-command prompt form |
| 409 | This function reads a Lisp expression in the minibuffer, evaluates it, |
| 410 | then returns the result. The difference between this command and |
| 411 | @code{eval-minibuffer} is that here the initial @var{form} is not |
| 412 | optional and it is treated as a Lisp object to be converted to printed |
| 413 | representation rather than as a string of text. It is printed with |
| 414 | @code{prin1}, so if it is a string, double-quote characters (@samp{"}) |
| 415 | appear in the initial text. @xref{Output Functions}. |
| 416 | |
| 417 | In the following example, we offer the user an expression with initial |
| 418 | text that is already a valid form: |
| 419 | |
| 420 | @smallexample |
| 421 | @group |
| 422 | (edit-and-eval-command "Please edit: " '(forward-word 1)) |
| 423 | |
| 424 | ;; @r{After evaluation of the preceding expression,} |
| 425 | ;; @r{the following appears in the minibuffer:} |
| 426 | @end group |
| 427 | |
| 428 | @group |
| 429 | ---------- Buffer: Minibuffer ---------- |
| 430 | Please edit: (forward-word 1)@point{} |
| 431 | ---------- Buffer: Minibuffer ---------- |
| 432 | @end group |
| 433 | @end smallexample |
| 434 | |
| 435 | @noindent |
| 436 | Typing @key{RET} right away would exit the minibuffer and evaluate the |
| 437 | expression, thus moving point forward one word. |
| 438 | @end defun |
| 439 | |
| 440 | @node Minibuffer History |
| 441 | @section Minibuffer History |
| 442 | @cindex minibuffer history |
| 443 | @cindex history list |
| 444 | |
| 445 | A @dfn{minibuffer history list} records previous minibuffer inputs |
| 446 | so the user can reuse them conveniently. It is a variable whose value |
| 447 | is a list of strings (previous inputs), most recent first. |
| 448 | |
| 449 | There are many separate minibuffer history lists, used for different |
| 450 | kinds of inputs. It's the Lisp programmer's job to specify the right |
| 451 | history list for each use of the minibuffer. |
| 452 | |
| 453 | You specify a minibuffer history list with the optional @var{history} |
| 454 | argument to @code{read-from-minibuffer} or @code{completing-read}. |
| 455 | Here are the possible values for it: |
| 456 | |
| 457 | @table @asis |
| 458 | @item @var{variable} |
| 459 | Use @var{variable} (a symbol) as the history list. |
| 460 | |
| 461 | @item (@var{variable} . @var{startpos}) |
| 462 | Use @var{variable} (a symbol) as the history list, and assume that the |
| 463 | initial history position is @var{startpos} (a nonnegative integer). |
| 464 | |
| 465 | Specifying 0 for @var{startpos} is equivalent to just specifying the |
| 466 | symbol @var{variable}. @code{previous-history-element} will display |
| 467 | the most recent element of the history list in the minibuffer. If you |
| 468 | specify a positive @var{startpos}, the minibuffer history functions |
| 469 | behave as if @code{(elt @var{variable} (1- @var{startpos}))} were the |
| 470 | history element currently shown in the minibuffer. |
| 471 | |
| 472 | For consistency, you should also specify that element of the history |
| 473 | as the initial minibuffer contents, using the @var{initial} argument |
| 474 | to the minibuffer input function (@pxref{Initial Input}). |
| 475 | @end table |
| 476 | |
| 477 | If you don't specify @var{history}, then the default history list |
| 478 | @code{minibuffer-history} is used. For other standard history lists, |
| 479 | see below. You can also create your own history list variable; just |
| 480 | initialize it to @code{nil} before the first use. |
| 481 | |
| 482 | Both @code{read-from-minibuffer} and @code{completing-read} add new |
| 483 | elements to the history list automatically, and provide commands to |
| 484 | allow the user to reuse items on the list. The only thing your program |
| 485 | needs to do to use a history list is to initialize it and to pass its |
| 486 | name to the input functions when you wish. But it is safe to modify the |
| 487 | list by hand when the minibuffer input functions are not using it. |
| 488 | |
| 489 | Emacs functions that add a new element to a history list can also |
| 490 | delete old elements if the list gets too long. The variable |
| 491 | @code{history-length} specifies the maximum length for most history |
| 492 | lists. To specify a different maximum length for a particular history |
| 493 | list, put the length in the @code{history-length} property of the |
| 494 | history list symbol. The variable @code{history-delete-duplicates} |
| 495 | specifies whether to delete duplicates in history. |
| 496 | |
| 497 | @defun add-to-history history-var newelt &optional maxelt keep-all |
| 498 | This function adds a new element @var{newelt}, if it isn't the empty |
| 499 | string, to the history list stored in the variable @var{history-var}, |
| 500 | and returns the updated history list. It limits the list length to |
| 501 | the value of @var{maxelt} (if non-@code{nil}) or @code{history-length} |
| 502 | (described below). The possible values of @var{maxelt} have the same |
| 503 | meaning as the values of @code{history-length}. |
| 504 | |
| 505 | Normally, @code{add-to-history} removes duplicate members from the |
| 506 | history list if @code{history-delete-duplicates} is non-@code{nil}. |
| 507 | However, if @var{keep-all} is non-@code{nil}, that says not to remove |
| 508 | duplicates, and to add @var{newelt} to the list even if it is empty. |
| 509 | @end defun |
| 510 | |
| 511 | @defvar history-add-new-input |
| 512 | If the value of this variable is @code{nil}, standard functions that |
| 513 | read from the minibuffer don't add new elements to the history list. |
| 514 | This lets Lisp programs explicitly manage input history by using |
| 515 | @code{add-to-history}. The default value is @code{t}. |
| 516 | @end defvar |
| 517 | |
| 518 | @defopt history-length |
| 519 | The value of this variable specifies the maximum length for all |
| 520 | history lists that don't specify their own maximum lengths. If the |
| 521 | value is @code{t}, that means there is no maximum (don't delete old |
| 522 | elements). If a history list variable's symbol has a non-@code{nil} |
| 523 | @code{history-length} property, it overrides this variable for that |
| 524 | particular history list. |
| 525 | @end defopt |
| 526 | |
| 527 | @defopt history-delete-duplicates |
| 528 | If the value of this variable is @code{t}, that means when adding a |
| 529 | new history element, all previous identical elements are deleted. |
| 530 | @end defopt |
| 531 | |
| 532 | Here are some of the standard minibuffer history list variables: |
| 533 | |
| 534 | @defvar minibuffer-history |
| 535 | The default history list for minibuffer history input. |
| 536 | @end defvar |
| 537 | |
| 538 | @defvar query-replace-history |
| 539 | A history list for arguments to @code{query-replace} (and similar |
| 540 | arguments to other commands). |
| 541 | @end defvar |
| 542 | |
| 543 | @defvar file-name-history |
| 544 | A history list for file-name arguments. |
| 545 | @end defvar |
| 546 | |
| 547 | @defvar buffer-name-history |
| 548 | A history list for buffer-name arguments. |
| 549 | @end defvar |
| 550 | |
| 551 | @defvar regexp-history |
| 552 | A history list for regular expression arguments. |
| 553 | @end defvar |
| 554 | |
| 555 | @defvar extended-command-history |
| 556 | A history list for arguments that are names of extended commands. |
| 557 | @end defvar |
| 558 | |
| 559 | @defvar shell-command-history |
| 560 | A history list for arguments that are shell commands. |
| 561 | @end defvar |
| 562 | |
| 563 | @defvar read-expression-history |
| 564 | A history list for arguments that are Lisp expressions to evaluate. |
| 565 | @end defvar |
| 566 | |
| 567 | @defvar face-name-history |
| 568 | A history list for arguments that are faces. |
| 569 | @end defvar |
| 570 | |
| 571 | @c Less common: coding-system-history, input-method-history, |
| 572 | @c command-history, grep-history, grep-find-history, |
| 573 | @c read-envvar-name-history, setenv-history, yes-or-no-p-history. |
| 574 | |
| 575 | @node Initial Input |
| 576 | @section Initial Input |
| 577 | |
| 578 | Several of the functions for minibuffer input have an argument called |
| 579 | @var{initial}. This is a mostly-deprecated |
| 580 | feature for specifying that the minibuffer should start out with |
| 581 | certain text, instead of empty as usual. |
| 582 | |
| 583 | If @var{initial} is a string, the minibuffer starts out containing the |
| 584 | text of the string, with point at the end, when the user starts to |
| 585 | edit the text. If the user simply types @key{RET} to exit the |
| 586 | minibuffer, it will use the initial input string to determine the |
| 587 | value to return. |
| 588 | |
| 589 | @strong{We discourage use of a non-@code{nil} value for |
| 590 | @var{initial}}, because initial input is an intrusive interface. |
| 591 | History lists and default values provide a much more convenient method |
| 592 | to offer useful default inputs to the user. |
| 593 | |
| 594 | There is just one situation where you should specify a string for an |
| 595 | @var{initial} argument. This is when you specify a cons cell for the |
| 596 | @var{history} argument. @xref{Minibuffer History}. |
| 597 | |
| 598 | @var{initial} can also be a cons cell of the form @code{(@var{string} |
| 599 | . @var{position})}. This means to insert @var{string} in the |
| 600 | minibuffer but put point at @var{position} within the string's text. |
| 601 | |
| 602 | As a historical accident, @var{position} was implemented |
| 603 | inconsistently in different functions. In @code{completing-read}, |
| 604 | @var{position}'s value is interpreted as origin-zero; that is, a value |
| 605 | of 0 means the beginning of the string, 1 means after the first |
| 606 | character, etc. In @code{read-minibuffer}, and the other |
| 607 | non-completion minibuffer input functions that support this argument, |
| 608 | 1 means the beginning of the string, 2 means after the first character, |
| 609 | etc. |
| 610 | |
| 611 | Use of a cons cell as the value for @var{initial} arguments is deprecated. |
| 612 | |
| 613 | @node Completion |
| 614 | @section Completion |
| 615 | @cindex completion |
| 616 | |
| 617 | @dfn{Completion} is a feature that fills in the rest of a name |
| 618 | starting from an abbreviation for it. Completion works by comparing the |
| 619 | user's input against a list of valid names and determining how much of |
| 620 | the name is determined uniquely by what the user has typed. For |
| 621 | example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then |
| 622 | @c "This is the sort of English up with which I will not put." |
| 623 | type the first few letters of the name of the buffer to which you wish |
| 624 | to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs |
| 625 | extends the name as far as it can. |
| 626 | |
| 627 | Standard Emacs commands offer completion for names of symbols, files, |
| 628 | buffers, and processes; with the functions in this section, you can |
| 629 | implement completion for other kinds of names. |
| 630 | |
| 631 | The @code{try-completion} function is the basic primitive for |
| 632 | completion: it returns the longest determined completion of a given |
| 633 | initial string, with a given set of strings to match against. |
| 634 | |
| 635 | The function @code{completing-read} provides a higher-level interface |
| 636 | for completion. A call to @code{completing-read} specifies how to |
| 637 | determine the list of valid names. The function then activates the |
| 638 | minibuffer with a local keymap that binds a few keys to commands useful |
| 639 | for completion. Other functions provide convenient simple interfaces |
| 640 | for reading certain kinds of names with completion. |
| 641 | |
| 642 | @menu |
| 643 | * Basic Completion:: Low-level functions for completing strings. |
| 644 | * Minibuffer Completion:: Invoking the minibuffer with completion. |
| 645 | * Completion Commands:: Minibuffer commands that do completion. |
| 646 | * High-Level Completion:: Convenient special cases of completion |
| 647 | (reading buffer names, variable names, etc.). |
| 648 | * Reading File Names:: Using completion to read file names and |
| 649 | shell commands. |
| 650 | * Completion Variables:: Variables controlling completion behavior. |
| 651 | * Programmed Completion:: Writing your own completion function. |
| 652 | * Completion in Buffers:: Completing text in ordinary buffers. |
| 653 | @end menu |
| 654 | |
| 655 | @node Basic Completion |
| 656 | @subsection Basic Completion Functions |
| 657 | |
| 658 | The following completion functions have nothing in themselves to do |
| 659 | with minibuffers. We describe them here to keep them near the |
| 660 | higher-level completion features that do use the minibuffer. |
| 661 | |
| 662 | @defun try-completion string collection &optional predicate |
| 663 | This function returns the longest common substring of all possible |
| 664 | completions of @var{string} in @var{collection}. |
| 665 | |
| 666 | @cindex completion table |
| 667 | The @var{collection} argument is called the @dfn{completion table}. |
| 668 | Its value must be a list of strings, an alist whose keys are strings |
| 669 | or symbols, an obarray, a hash table, or a completion function. |
| 670 | |
| 671 | Completion compares @var{string} against each of the permissible |
| 672 | completions specified by @var{collection}. If no permissible |
| 673 | completions match, @code{try-completion} returns @code{nil}. If there |
| 674 | is just one matching completion, and the match is exact, it returns |
| 675 | @code{t}. Otherwise, it returns the longest initial sequence common |
| 676 | to all possible matching completions. |
| 677 | |
| 678 | If @var{collection} is an alist (@pxref{Association Lists}), the |
| 679 | permissible completions are the elements of the alist that are either |
| 680 | strings, or conses whose @sc{car} is a string or symbol. |
| 681 | Symbols are converted to strings using @code{symbol-name}. Other |
| 682 | elements of the alist are ignored. (Remember that in Emacs Lisp, the |
| 683 | elements of alists do not @emph{have} to be conses.) In particular, a |
| 684 | list of strings is allowed, even though we usually do not |
| 685 | think of such lists as alists. |
| 686 | |
| 687 | @cindex obarray in completion |
| 688 | If @var{collection} is an obarray (@pxref{Creating Symbols}), the names |
| 689 | of all symbols in the obarray form the set of permissible completions. |
| 690 | |
| 691 | If @var{collection} is a hash table, then the keys that are strings |
| 692 | are the possible completions. Other keys are ignored. |
| 693 | |
| 694 | You can also use a function as @var{collection}. Then the function is |
| 695 | solely responsible for performing completion; @code{try-completion} |
| 696 | returns whatever this function returns. The function is called with |
| 697 | three arguments: @var{string}, @var{predicate} and @code{nil} (the |
| 698 | third argument is so that the same function can be used |
| 699 | in @code{all-completions} and do the appropriate thing in either |
| 700 | case). @xref{Programmed Completion}. |
| 701 | |
| 702 | If the argument @var{predicate} is non-@code{nil}, then it must be a |
| 703 | function of one argument, unless @var{collection} is a hash table, in |
| 704 | which case it should be a function of two arguments. It is used to |
| 705 | test each possible match, and the match is accepted only if |
| 706 | @var{predicate} returns non-@code{nil}. The argument given to |
| 707 | @var{predicate} is either a string or a cons cell (the @sc{car} of |
| 708 | which is a string) from the alist, or a symbol (@emph{not} a symbol |
| 709 | name) from the obarray. If @var{collection} is a hash table, |
| 710 | @var{predicate} is called with two arguments, the string key and the |
| 711 | associated value. |
| 712 | |
| 713 | In addition, to be acceptable, a completion must also match all the |
| 714 | regular expressions in @code{completion-regexp-list}. (Unless |
| 715 | @var{collection} is a function, in which case that function has to |
| 716 | handle @code{completion-regexp-list} itself.) |
| 717 | |
| 718 | In the first of the following examples, the string @samp{foo} is |
| 719 | matched by three of the alist @sc{car}s. All of the matches begin with |
| 720 | the characters @samp{fooba}, so that is the result. In the second |
| 721 | example, there is only one possible match, and it is exact, so the |
| 722 | return value is @code{t}. |
| 723 | |
| 724 | @smallexample |
| 725 | @group |
| 726 | (try-completion |
| 727 | "foo" |
| 728 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))) |
| 729 | @result{} "fooba" |
| 730 | @end group |
| 731 | |
| 732 | @group |
| 733 | (try-completion "foo" '(("barfoo" 2) ("foo" 3))) |
| 734 | @result{} t |
| 735 | @end group |
| 736 | @end smallexample |
| 737 | |
| 738 | In the following example, numerous symbols begin with the characters |
| 739 | @samp{forw}, and all of them begin with the word @samp{forward}. In |
| 740 | most of the symbols, this is followed with a @samp{-}, but not in all, |
| 741 | so no more than @samp{forward} can be completed. |
| 742 | |
| 743 | @smallexample |
| 744 | @group |
| 745 | (try-completion "forw" obarray) |
| 746 | @result{} "forward" |
| 747 | @end group |
| 748 | @end smallexample |
| 749 | |
| 750 | Finally, in the following example, only two of the three possible |
| 751 | matches pass the predicate @code{test} (the string @samp{foobaz} is |
| 752 | too short). Both of those begin with the string @samp{foobar}. |
| 753 | |
| 754 | @smallexample |
| 755 | @group |
| 756 | (defun test (s) |
| 757 | (> (length (car s)) 6)) |
| 758 | @result{} test |
| 759 | @end group |
| 760 | @group |
| 761 | (try-completion |
| 762 | "foo" |
| 763 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) |
| 764 | 'test) |
| 765 | @result{} "foobar" |
| 766 | @end group |
| 767 | @end smallexample |
| 768 | @end defun |
| 769 | |
| 770 | @c Removed obsolete argument nospace. |
| 771 | @defun all-completions string collection &optional predicate |
| 772 | This function returns a list of all possible completions of |
| 773 | @var{string}. The arguments to this function |
| 774 | @c (aside from @var{nospace}) |
| 775 | are the same as those of @code{try-completion}, and it |
| 776 | uses @code{completion-regexp-list} in the same way that |
| 777 | @code{try-completion} does. |
| 778 | |
| 779 | @ignore |
| 780 | The optional argument @var{nospace} is obsolete. If it is |
| 781 | non-@code{nil}, completions that start with a space are ignored unless |
| 782 | @var{string} starts with a space. |
| 783 | @end ignore |
| 784 | |
| 785 | If @var{collection} is a function, it is called with three arguments: |
| 786 | @var{string}, @var{predicate} and @code{t}; then @code{all-completions} |
| 787 | returns whatever the function returns. @xref{Programmed Completion}. |
| 788 | |
| 789 | Here is an example, using the function @code{test} shown in the |
| 790 | example for @code{try-completion}: |
| 791 | |
| 792 | @smallexample |
| 793 | @group |
| 794 | (defun test (s) |
| 795 | (> (length (car s)) 6)) |
| 796 | @result{} test |
| 797 | @end group |
| 798 | |
| 799 | @group |
| 800 | (all-completions |
| 801 | "foo" |
| 802 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) |
| 803 | 'test) |
| 804 | @result{} ("foobar1" "foobar2") |
| 805 | @end group |
| 806 | @end smallexample |
| 807 | @end defun |
| 808 | |
| 809 | @defun test-completion string collection &optional predicate |
| 810 | @anchor{Definition of test-completion} |
| 811 | This function returns non-@code{nil} if @var{string} is a valid |
| 812 | completion alternative specified by @var{collection} and |
| 813 | @var{predicate}. The arguments are the same as in |
| 814 | @code{try-completion}. For instance, if @var{collection} is a list of |
| 815 | strings, this is true if @var{string} appears in the list and |
| 816 | @var{predicate} is satisfied. |
| 817 | |
| 818 | This function uses @code{completion-regexp-list} in the same |
| 819 | way that @code{try-completion} does. |
| 820 | |
| 821 | If @var{predicate} is non-@code{nil} and if @var{collection} contains |
| 822 | several strings that are equal to each other, as determined by |
| 823 | @code{compare-strings} according to @code{completion-ignore-case}, |
| 824 | then @var{predicate} should accept either all or none of them. |
| 825 | Otherwise, the return value of @code{test-completion} is essentially |
| 826 | unpredictable. |
| 827 | |
| 828 | If @var{collection} is a function, it is called with three arguments, |
| 829 | the values @var{string}, @var{predicate} and @code{lambda}; whatever |
| 830 | it returns, @code{test-completion} returns in turn. |
| 831 | @end defun |
| 832 | |
| 833 | @defun completion-boundaries string collection predicate suffix |
| 834 | This function returns the boundaries of the field on which @var{collection} |
| 835 | will operate, assuming that @var{string} holds the text before point |
| 836 | and @var{suffix} holds the text after point. |
| 837 | |
| 838 | Normally completion operates on the whole string, so for all normal |
| 839 | collections, this will always return @code{(0 . (length |
| 840 | @var{suffix}))}. But more complex completion such as completion on |
| 841 | files is done one field at a time. For example, completion of |
| 842 | @code{"/usr/sh"} will include @code{"/usr/share/"} but not |
| 843 | @code{"/usr/share/doc"} even if @code{"/usr/share/doc"} exists. |
| 844 | Also @code{all-completions} on @code{"/usr/sh"} will not include |
| 845 | @code{"/usr/share/"} but only @code{"share/"}. So if @var{string} is |
| 846 | @code{"/usr/sh"} and @var{suffix} is @code{"e/doc"}, |
| 847 | @code{completion-boundaries} will return @code{(5 . 1)} which tells us |
| 848 | that the @var{collection} will only return completion information that |
| 849 | pertains to the area after @code{"/usr/"} and before @code{"/doc"}. |
| 850 | @end defun |
| 851 | |
| 852 | If you store a completion alist in a variable, you should mark the |
| 853 | variable as ``risky'' by giving it a non-@code{nil} |
| 854 | @code{risky-local-variable} property. @xref{File Local Variables}. |
| 855 | |
| 856 | @defvar completion-ignore-case |
| 857 | If the value of this variable is non-@code{nil}, case is not |
| 858 | considered significant in completion. Within @code{read-file-name}, |
| 859 | this variable is overridden by |
| 860 | @code{read-file-name-completion-ignore-case} (@pxref{Reading File |
| 861 | Names}); within @code{read-buffer}, it is overridden by |
| 862 | @code{read-buffer-completion-ignore-case} (@pxref{High-Level |
| 863 | Completion}). |
| 864 | @end defvar |
| 865 | |
| 866 | @defvar completion-regexp-list |
| 867 | This is a list of regular expressions. The completion functions only |
| 868 | consider a completion acceptable if it matches all regular expressions |
| 869 | in this list, with @code{case-fold-search} (@pxref{Searching and Case}) |
| 870 | bound to the value of @code{completion-ignore-case}. |
| 871 | @end defvar |
| 872 | |
| 873 | @defmac lazy-completion-table var fun |
| 874 | This macro provides a way to initialize the variable @var{var} as a |
| 875 | collection for completion in a lazy way, not computing its actual |
| 876 | contents until they are first needed. You use this macro to produce a |
| 877 | value that you store in @var{var}. The actual computation of the |
| 878 | proper value is done the first time you do completion using @var{var}. |
| 879 | It is done by calling @var{fun} with no arguments. The |
| 880 | value @var{fun} returns becomes the permanent value of @var{var}. |
| 881 | |
| 882 | Here is an example: |
| 883 | |
| 884 | @smallexample |
| 885 | (defvar foo (lazy-completion-table foo make-my-alist)) |
| 886 | @end smallexample |
| 887 | @end defmac |
| 888 | |
| 889 | @node Minibuffer Completion |
| 890 | @subsection Completion and the Minibuffer |
| 891 | @cindex minibuffer completion |
| 892 | @cindex reading from minibuffer with completion |
| 893 | |
| 894 | This section describes the basic interface for reading from the |
| 895 | minibuffer with completion. |
| 896 | |
| 897 | @defun completing-read prompt collection &optional predicate require-match initial history default inherit-input-method |
| 898 | This function reads a string in the minibuffer, assisting the user by |
| 899 | providing completion. It activates the minibuffer with prompt |
| 900 | @var{prompt}, which must be a string. |
| 901 | |
| 902 | The actual completion is done by passing the completion table |
| 903 | @var{collection} and the completion predicate @var{predicate} to the |
| 904 | function @code{try-completion} (@pxref{Basic Completion}). This |
| 905 | happens in certain commands bound in the local keymaps used for |
| 906 | completion. Some of these commands also call @code{test-completion}. |
| 907 | Thus, if @var{predicate} is non-@code{nil}, it should be compatible |
| 908 | with @var{collection} and @code{completion-ignore-case}. |
| 909 | @xref{Definition of test-completion}. |
| 910 | |
| 911 | The value of the optional argument @var{require-match} determines how |
| 912 | the user may exit the minibuffer: |
| 913 | |
| 914 | @itemize @bullet |
| 915 | @item |
| 916 | If @code{nil}, the usual minibuffer exit commands work regardless of |
| 917 | the input in the minibuffer. |
| 918 | |
| 919 | @item |
| 920 | If @code{t}, the usual minibuffer exit commands won't exit unless the |
| 921 | input completes to an element of @var{collection}. |
| 922 | |
| 923 | @item |
| 924 | If @code{confirm}, the user can exit with any input, but is asked for |
| 925 | confirmation if the input is not an element of @var{collection}. |
| 926 | |
| 927 | @item |
| 928 | If @code{confirm-after-completion}, the user can exit with any input, |
| 929 | but is asked for confirmation if the preceding command was a |
| 930 | completion command (i.e., one of the commands in |
| 931 | @code{minibuffer-confirm-exit-commands}) and the resulting input is |
| 932 | not an element of @var{collection}. @xref{Completion Commands}. |
| 933 | |
| 934 | @item |
| 935 | Any other value of @var{require-match} behaves like @code{t}, except |
| 936 | that the exit commands won't exit if it performs completion. |
| 937 | @end itemize |
| 938 | |
| 939 | However, empty input is always permitted, regardless of the value of |
| 940 | @var{require-match}; in that case, @code{completing-read} returns the |
| 941 | first element of @var{default}, if it is a list; @code{""}, if |
| 942 | @var{default} is @code{nil}; or @var{default}. The string or strings |
| 943 | in @var{default} are also available to the user through the history |
| 944 | commands. |
| 945 | |
| 946 | The function @code{completing-read} uses |
| 947 | @code{minibuffer-local-completion-map} as the keymap if |
| 948 | @var{require-match} is @code{nil}, and uses |
| 949 | @code{minibuffer-local-must-match-map} if @var{require-match} is |
| 950 | non-@code{nil}. @xref{Completion Commands}. |
| 951 | |
| 952 | The argument @var{history} specifies which history list variable to use for |
| 953 | saving the input and for minibuffer history commands. It defaults to |
| 954 | @code{minibuffer-history}. @xref{Minibuffer History}. |
| 955 | |
| 956 | The argument @var{initial} is mostly deprecated; we recommend using a |
| 957 | non-@code{nil} value only in conjunction with specifying a cons cell |
| 958 | for @var{history}. @xref{Initial Input}. For default input, use |
| 959 | @var{default} instead. |
| 960 | |
| 961 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
| 962 | minibuffer inherits the current input method (@pxref{Input |
| 963 | Methods}) and the setting of @code{enable-multibyte-characters} |
| 964 | (@pxref{Text Representations}) from whichever buffer was current before |
| 965 | entering the minibuffer. |
| 966 | |
| 967 | If the variable @code{completion-ignore-case} is |
| 968 | non-@code{nil}, completion ignores case when comparing the input |
| 969 | against the possible matches. @xref{Basic Completion}. In this mode |
| 970 | of operation, @var{predicate} must also ignore case, or you will get |
| 971 | surprising results. |
| 972 | |
| 973 | Here's an example of using @code{completing-read}: |
| 974 | |
| 975 | @smallexample |
| 976 | @group |
| 977 | (completing-read |
| 978 | "Complete a foo: " |
| 979 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) |
| 980 | nil t "fo") |
| 981 | @end group |
| 982 | |
| 983 | @group |
| 984 | ;; @r{After evaluation of the preceding expression,} |
| 985 | ;; @r{the following appears in the minibuffer:} |
| 986 | |
| 987 | ---------- Buffer: Minibuffer ---------- |
| 988 | Complete a foo: fo@point{} |
| 989 | ---------- Buffer: Minibuffer ---------- |
| 990 | @end group |
| 991 | @end smallexample |
| 992 | |
| 993 | @noindent |
| 994 | If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}}, |
| 995 | @code{completing-read} returns @code{barfoo}. |
| 996 | |
| 997 | The @code{completing-read} function binds variables to pass |
| 998 | information to the commands that actually do completion. |
| 999 | They are described in the following section. |
| 1000 | @end defun |
| 1001 | |
| 1002 | @defvar completing-read-function |
| 1003 | The value of this variable must be a function, which is called by |
| 1004 | @code{completing-read} to actually do its work. It should accept the |
| 1005 | same arguments as @code{completing-read}. This can be bound to a |
| 1006 | different function to completely override the normal behavior of |
| 1007 | @code{completing-read}. |
| 1008 | @end defvar |
| 1009 | |
| 1010 | @node Completion Commands |
| 1011 | @subsection Minibuffer Commands that Do Completion |
| 1012 | |
| 1013 | This section describes the keymaps, commands and user options used |
| 1014 | in the minibuffer to do completion. |
| 1015 | |
| 1016 | @defvar minibuffer-completion-table |
| 1017 | The value of this variable is the completion table used for completion |
| 1018 | in the minibuffer. This is the global variable that contains what |
| 1019 | @code{completing-read} passes to @code{try-completion}. It is used by |
| 1020 | minibuffer completion commands such as |
| 1021 | @code{minibuffer-complete-word}. |
| 1022 | @end defvar |
| 1023 | |
| 1024 | @defvar minibuffer-completion-predicate |
| 1025 | This variable's value is the predicate that @code{completing-read} |
| 1026 | passes to @code{try-completion}. The variable is also used by the other |
| 1027 | minibuffer completion functions. |
| 1028 | @end defvar |
| 1029 | |
| 1030 | @defvar minibuffer-completion-confirm |
| 1031 | This variable determines whether Emacs asks for confirmation before |
| 1032 | exiting the minibuffer; @code{completing-read} binds this variable, |
| 1033 | and the function @code{minibuffer-complete-and-exit} checks the value |
| 1034 | before exiting. If the value is @code{nil}, confirmation is not |
| 1035 | required. If the value is @code{confirm}, the user may exit with an |
| 1036 | input that is not a valid completion alternative, but Emacs asks for |
| 1037 | confirmation. If the value is @code{confirm-after-completion}, the |
| 1038 | user may exit with an input that is not a valid completion |
| 1039 | alternative, but Emacs asks for confirmation if the user submitted the |
| 1040 | input right after any of the completion commands in |
| 1041 | @code{minibuffer-confirm-exit-commands}. |
| 1042 | @end defvar |
| 1043 | |
| 1044 | @defvar minibuffer-confirm-exit-commands |
| 1045 | This variable holds a list of commands that cause Emacs to ask for |
| 1046 | confirmation before exiting the minibuffer, if the @var{require-match} |
| 1047 | argument to @code{completing-read} is @code{confirm-after-completion}. |
| 1048 | The confirmation is requested if the user attempts to exit the |
| 1049 | minibuffer immediately after calling any command in this list. |
| 1050 | @end defvar |
| 1051 | |
| 1052 | @deffn Command minibuffer-complete-word |
| 1053 | This function completes the minibuffer contents by at most a single |
| 1054 | word. Even if the minibuffer contents have only one completion, |
| 1055 | @code{minibuffer-complete-word} does not add any characters beyond the |
| 1056 | first character that is not a word constituent. @xref{Syntax Tables}. |
| 1057 | @end deffn |
| 1058 | |
| 1059 | @deffn Command minibuffer-complete |
| 1060 | This function completes the minibuffer contents as far as possible. |
| 1061 | @end deffn |
| 1062 | |
| 1063 | @deffn Command minibuffer-complete-and-exit |
| 1064 | This function completes the minibuffer contents, and exits if |
| 1065 | confirmation is not required, i.e., if |
| 1066 | @code{minibuffer-completion-confirm} is @code{nil}. If confirmation |
| 1067 | @emph{is} required, it is given by repeating this command |
| 1068 | immediately---the command is programmed to work without confirmation |
| 1069 | when run twice in succession. |
| 1070 | @end deffn |
| 1071 | |
| 1072 | @deffn Command minibuffer-completion-help |
| 1073 | This function creates a list of the possible completions of the |
| 1074 | current minibuffer contents. It works by calling @code{all-completions} |
| 1075 | using the value of the variable @code{minibuffer-completion-table} as |
| 1076 | the @var{collection} argument, and the value of |
| 1077 | @code{minibuffer-completion-predicate} as the @var{predicate} argument. |
| 1078 | The list of completions is displayed as text in a buffer named |
| 1079 | @file{*Completions*}. |
| 1080 | @end deffn |
| 1081 | |
| 1082 | @defun display-completion-list completions &optional common-substring |
| 1083 | This function displays @var{completions} to the stream in |
| 1084 | @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more |
| 1085 | information about streams.) The argument @var{completions} is normally |
| 1086 | a list of completions just returned by @code{all-completions}, but it |
| 1087 | does not have to be. Each element may be a symbol or a string, either |
| 1088 | of which is simply printed. It can also be a list of two strings, |
| 1089 | which is printed as if the strings were concatenated. The first of |
| 1090 | the two strings is the actual completion, the second string serves as |
| 1091 | annotation. |
| 1092 | |
| 1093 | The argument @var{common-substring} is the prefix that is common to |
| 1094 | all the completions. With normal Emacs completion, it is usually the |
| 1095 | same as the string that was completed. @code{display-completion-list} |
| 1096 | uses this to highlight text in the completion list for better visual |
| 1097 | feedback. This is not needed in the minibuffer; for minibuffer |
| 1098 | completion, you can pass @code{nil}. |
| 1099 | |
| 1100 | This function is called by @code{minibuffer-completion-help}. A |
| 1101 | common way to use it is together with |
| 1102 | @code{with-output-to-temp-buffer}, like this: |
| 1103 | |
| 1104 | @example |
| 1105 | (with-output-to-temp-buffer "*Completions*" |
| 1106 | (display-completion-list |
| 1107 | (all-completions (buffer-string) my-alist) |
| 1108 | (buffer-string))) |
| 1109 | @end example |
| 1110 | @end defun |
| 1111 | |
| 1112 | @defopt completion-auto-help |
| 1113 | If this variable is non-@code{nil}, the completion commands |
| 1114 | automatically display a list of possible completions whenever nothing |
| 1115 | can be completed because the next character is not uniquely determined. |
| 1116 | @end defopt |
| 1117 | |
| 1118 | @defvar minibuffer-local-completion-map |
| 1119 | @code{completing-read} uses this value as the local keymap when an |
| 1120 | exact match of one of the completions is not required. By default, this |
| 1121 | keymap makes the following bindings: |
| 1122 | |
| 1123 | @table @asis |
| 1124 | @item @kbd{?} |
| 1125 | @code{minibuffer-completion-help} |
| 1126 | |
| 1127 | @item @key{SPC} |
| 1128 | @code{minibuffer-complete-word} |
| 1129 | |
| 1130 | @item @key{TAB} |
| 1131 | @code{minibuffer-complete} |
| 1132 | @end table |
| 1133 | |
| 1134 | @noindent |
| 1135 | and uses @code{minibuffer-local-map} as its parent keymap |
| 1136 | (@pxref{Definition of minibuffer-local-map}). |
| 1137 | @end defvar |
| 1138 | |
| 1139 | @defvar minibuffer-local-must-match-map |
| 1140 | @code{completing-read} uses this value as the local keymap when an |
| 1141 | exact match of one of the completions is required. Therefore, no keys |
| 1142 | are bound to @code{exit-minibuffer}, the command that exits the |
| 1143 | minibuffer unconditionally. By default, this keymap makes the following |
| 1144 | bindings: |
| 1145 | |
| 1146 | @table @asis |
| 1147 | @item @kbd{C-j} |
| 1148 | @code{minibuffer-complete-and-exit} |
| 1149 | |
| 1150 | @item @key{RET} |
| 1151 | @code{minibuffer-complete-and-exit} |
| 1152 | @end table |
| 1153 | |
| 1154 | @noindent |
| 1155 | and uses @code{minibuffer-local-completion-map} as its parent keymap. |
| 1156 | @end defvar |
| 1157 | |
| 1158 | @defvar minibuffer-local-filename-completion-map |
| 1159 | This is a sparse keymap that simply unbinds @key{SPC}; because |
| 1160 | filenames can contain spaces. The function @code{read-file-name} |
| 1161 | combines this keymap with either @code{minibuffer-local-completion-map} |
| 1162 | or @code{minibuffer-local-must-match-map}. |
| 1163 | @end defvar |
| 1164 | |
| 1165 | |
| 1166 | @node High-Level Completion |
| 1167 | @subsection High-Level Completion Functions |
| 1168 | |
| 1169 | This section describes the higher-level convenience functions for |
| 1170 | reading certain sorts of names with completion. |
| 1171 | |
| 1172 | In most cases, you should not call these functions in the middle of a |
| 1173 | Lisp function. When possible, do all minibuffer input as part of |
| 1174 | reading the arguments for a command, in the @code{interactive} |
| 1175 | specification. @xref{Defining Commands}. |
| 1176 | |
| 1177 | @defun read-buffer prompt &optional default require-match |
| 1178 | This function reads the name of a buffer and returns it as a string. |
| 1179 | The argument @var{default} is the default name to use, the value to |
| 1180 | return if the user exits with an empty minibuffer. If non-@code{nil}, |
| 1181 | it should be a string, a list of strings, or a buffer. If it is |
| 1182 | a list, the default value is the first element of this list. It is |
| 1183 | mentioned in the prompt, but is not inserted in the minibuffer as |
| 1184 | initial input. |
| 1185 | |
| 1186 | The argument @var{prompt} should be a string ending with a colon and a |
| 1187 | space. If @var{default} is non-@code{nil}, the function inserts it in |
| 1188 | @var{prompt} before the colon to follow the convention for reading from |
| 1189 | the minibuffer with a default value (@pxref{Programming Tips}). |
| 1190 | |
| 1191 | The optional argument @var{require-match} has the same meaning as in |
| 1192 | @code{completing-read}. @xref{Minibuffer Completion}. |
| 1193 | |
| 1194 | In the following example, the user enters @samp{minibuffer.t}, and |
| 1195 | then types @key{RET}. The argument @var{require-match} is @code{t}, |
| 1196 | and the only buffer name starting with the given input is |
| 1197 | @samp{minibuffer.texi}, so that name is the value. |
| 1198 | |
| 1199 | @example |
| 1200 | (read-buffer "Buffer name: " "foo" t) |
| 1201 | @group |
| 1202 | ;; @r{After evaluation of the preceding expression,} |
| 1203 | ;; @r{the following prompt appears,} |
| 1204 | ;; @r{with an empty minibuffer:} |
| 1205 | @end group |
| 1206 | |
| 1207 | @group |
| 1208 | ---------- Buffer: Minibuffer ---------- |
| 1209 | Buffer name (default foo): @point{} |
| 1210 | ---------- Buffer: Minibuffer ---------- |
| 1211 | @end group |
| 1212 | |
| 1213 | @group |
| 1214 | ;; @r{The user types @kbd{minibuffer.t @key{RET}}.} |
| 1215 | @result{} "minibuffer.texi" |
| 1216 | @end group |
| 1217 | @end example |
| 1218 | @end defun |
| 1219 | |
| 1220 | @defopt read-buffer-function |
| 1221 | This variable specifies how to read buffer names. The function is |
| 1222 | called with the arguments passed to @code{read-buffer}. For example, |
| 1223 | if you set this variable to @code{iswitchb-read-buffer}, all Emacs |
| 1224 | commands that call @code{read-buffer} to read a buffer name will |
| 1225 | actually use the @code{iswitchb} package to read it. |
| 1226 | @end defopt |
| 1227 | |
| 1228 | @defopt read-buffer-completion-ignore-case |
| 1229 | If this variable is non-@code{nil}, @code{read-buffer} ignores case |
| 1230 | when performing completion. |
| 1231 | @end defopt |
| 1232 | |
| 1233 | @defun read-command prompt &optional default |
| 1234 | This function reads the name of a command and returns it as a Lisp |
| 1235 | symbol. The argument @var{prompt} is used as in |
| 1236 | @code{read-from-minibuffer}. Recall that a command is anything for |
| 1237 | which @code{commandp} returns @code{t}, and a command name is a symbol |
| 1238 | for which @code{commandp} returns @code{t}. @xref{Interactive Call}. |
| 1239 | |
| 1240 | The argument @var{default} specifies what to return if the user enters |
| 1241 | null input. It can be a symbol, a string or a list of strings. If it |
| 1242 | is a string, @code{read-command} interns it before returning it. |
| 1243 | If it is a list, @code{read-command} interns the first element of this list. |
| 1244 | If @var{default} is @code{nil}, that means no default has been |
| 1245 | specified; then if the user enters null input, the return value is |
| 1246 | @code{(intern "")}, that is, a symbol whose name is an empty string. |
| 1247 | |
| 1248 | @example |
| 1249 | (read-command "Command name? ") |
| 1250 | |
| 1251 | @group |
| 1252 | ;; @r{After evaluation of the preceding expression,} |
| 1253 | ;; @r{the following prompt appears with an empty minibuffer:} |
| 1254 | @end group |
| 1255 | |
| 1256 | @group |
| 1257 | ---------- Buffer: Minibuffer ---------- |
| 1258 | Command name? |
| 1259 | ---------- Buffer: Minibuffer ---------- |
| 1260 | @end group |
| 1261 | @end example |
| 1262 | |
| 1263 | @noindent |
| 1264 | If the user types @kbd{forward-c @key{RET}}, then this function returns |
| 1265 | @code{forward-char}. |
| 1266 | |
| 1267 | The @code{read-command} function is a simplified interface to |
| 1268 | @code{completing-read}. It uses the variable @code{obarray} so as to |
| 1269 | complete in the set of extant Lisp symbols, and it uses the |
| 1270 | @code{commandp} predicate so as to accept only command names: |
| 1271 | |
| 1272 | @cindex @code{commandp} example |
| 1273 | @example |
| 1274 | @group |
| 1275 | (read-command @var{prompt}) |
| 1276 | @equiv{} |
| 1277 | (intern (completing-read @var{prompt} obarray |
| 1278 | 'commandp t nil)) |
| 1279 | @end group |
| 1280 | @end example |
| 1281 | @end defun |
| 1282 | |
| 1283 | @defun read-variable prompt &optional default |
| 1284 | @anchor{Definition of read-variable} |
| 1285 | This function reads the name of a customizable variable and returns it |
| 1286 | as a symbol. Its arguments have the same form as those of |
| 1287 | @code{read-command}. It behaves just like @code{read-command}, except |
| 1288 | that it uses the predicate @code{custom-variable-p} instead of |
| 1289 | @code{commandp}. |
| 1290 | @end defun |
| 1291 | |
| 1292 | @deffn Command read-color &optional prompt convert allow-empty display |
| 1293 | This function reads a string that is a color specification, either the |
| 1294 | color's name or an RGB hex value such as @code{#RRRGGGBBB}. It |
| 1295 | prompts with @var{prompt} (default: @code{"Color (name or #RGB triplet):"}) |
| 1296 | and provides completion for color names, but not for hex RGB values. |
| 1297 | In addition to names of standard colors, completion candidates include |
| 1298 | the foreground and background colors at point. |
| 1299 | |
| 1300 | Valid RGB values are described in @ref{Color Names}. |
| 1301 | |
| 1302 | The function's return value is the string typed by the user in the |
| 1303 | minibuffer. However, when called interactively or if the optional |
| 1304 | argument @var{convert} is non-@code{nil}, it converts any input color |
| 1305 | name into the corresponding RGB value string and instead returns that. |
| 1306 | This function requires a valid color specification to be input. |
| 1307 | Empty color names are allowed when @var{allow-empty} is |
| 1308 | non-@code{nil} and the user enters null input. |
| 1309 | |
| 1310 | Interactively, or when @var{display} is non-@code{nil}, the return |
| 1311 | value is also displayed in the echo area. |
| 1312 | @end deffn |
| 1313 | |
| 1314 | See also the functions @code{read-coding-system} and |
| 1315 | @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}, |
| 1316 | and @code{read-input-method-name}, in @ref{Input Methods}. |
| 1317 | |
| 1318 | @node Reading File Names |
| 1319 | @subsection Reading File Names |
| 1320 | @cindex read file names |
| 1321 | @cindex prompt for file name |
| 1322 | |
| 1323 | The high-level completion functions @code{read-file-name}, |
| 1324 | @code{read-directory-name}, and @code{read-shell-command} are designed |
| 1325 | to read file names, directory names, and shell commands, respectively. |
| 1326 | They provide special features, including automatic insertion of the |
| 1327 | default directory. |
| 1328 | |
| 1329 | @defun read-file-name prompt &optional directory default require-match initial predicate |
| 1330 | This function reads a file name, prompting with @var{prompt} and |
| 1331 | providing completion. |
| 1332 | |
| 1333 | As an exception, this function reads a file name using a graphical |
| 1334 | file dialog instead of the minibuffer, if all of the following are |
| 1335 | true: |
| 1336 | |
| 1337 | @enumerate |
| 1338 | @item |
| 1339 | It is invoked via a mouse command. |
| 1340 | |
| 1341 | @item |
| 1342 | The selected frame is on a graphical display supporting such dialogs. |
| 1343 | |
| 1344 | @item |
| 1345 | The variable @code{use-dialog-box} is non-@code{nil}. |
| 1346 | @xref{Dialog Boxes,, Dialog Boxes, emacs, The GNU Emacs Manual}. |
| 1347 | |
| 1348 | @item |
| 1349 | The @var{directory} argument, described below, does not specify a |
| 1350 | remote file. @xref{Remote Files,, Remote Files, emacs, The GNU Emacs Manual}. |
| 1351 | @end enumerate |
| 1352 | |
| 1353 | @noindent |
| 1354 | The exact behavior when using a graphical file dialog is |
| 1355 | platform-dependent. Here, we simply document the behavior when using |
| 1356 | the minibuffer. |
| 1357 | |
| 1358 | @code{read-file-name} does not automatically expand the returned file |
| 1359 | name. You must call @code{expand-file-name} yourself if an absolute |
| 1360 | file name is required. |
| 1361 | |
| 1362 | The optional argument @var{require-match} has the same meaning as in |
| 1363 | @code{completing-read}. @xref{Minibuffer Completion}. |
| 1364 | |
| 1365 | The argument @var{directory} specifies the directory to use for |
| 1366 | completing relative file names. It should be an absolute directory |
| 1367 | name. If the variable @code{insert-default-directory} is non-@code{nil}, |
| 1368 | @var{directory} is also inserted in the minibuffer as initial input. |
| 1369 | It defaults to the current buffer's value of @code{default-directory}. |
| 1370 | |
| 1371 | If you specify @var{initial}, that is an initial file name to insert |
| 1372 | in the buffer (after @var{directory}, if that is inserted). In this |
| 1373 | case, point goes at the beginning of @var{initial}. The default for |
| 1374 | @var{initial} is @code{nil}---don't insert any file name. To see what |
| 1375 | @var{initial} does, try the command @kbd{C-x C-v} in a buffer visiting |
| 1376 | a file. @strong{Please note:} we recommend using @var{default} rather |
| 1377 | than @var{initial} in most cases. |
| 1378 | |
| 1379 | If @var{default} is non-@code{nil}, then the function returns |
| 1380 | @var{default} if the user exits the minibuffer with the same non-empty |
| 1381 | contents that @code{read-file-name} inserted initially. The initial |
| 1382 | minibuffer contents are always non-empty if |
| 1383 | @code{insert-default-directory} is non-@code{nil}, as it is by |
| 1384 | default. @var{default} is not checked for validity, regardless of the |
| 1385 | value of @var{require-match}. However, if @var{require-match} is |
| 1386 | non-@code{nil}, the initial minibuffer contents should be a valid file |
| 1387 | (or directory) name. Otherwise @code{read-file-name} attempts |
| 1388 | completion if the user exits without any editing, and does not return |
| 1389 | @var{default}. @var{default} is also available through the history |
| 1390 | commands. |
| 1391 | |
| 1392 | If @var{default} is @code{nil}, @code{read-file-name} tries to find a |
| 1393 | substitute default to use in its place, which it treats in exactly the |
| 1394 | same way as if it had been specified explicitly. If @var{default} is |
| 1395 | @code{nil}, but @var{initial} is non-@code{nil}, then the default is |
| 1396 | the absolute file name obtained from @var{directory} and |
| 1397 | @var{initial}. If both @var{default} and @var{initial} are @code{nil} |
| 1398 | and the buffer is visiting a file, @code{read-file-name} uses the |
| 1399 | absolute file name of that file as default. If the buffer is not |
| 1400 | visiting a file, then there is no default. In that case, if the user |
| 1401 | types @key{RET} without any editing, @code{read-file-name} simply |
| 1402 | returns the pre-inserted contents of the minibuffer. |
| 1403 | |
| 1404 | If the user types @key{RET} in an empty minibuffer, this function |
| 1405 | returns an empty string, regardless of the value of |
| 1406 | @var{require-match}. This is, for instance, how the user can make the |
| 1407 | current buffer visit no file using @code{M-x set-visited-file-name}. |
| 1408 | |
| 1409 | If @var{predicate} is non-@code{nil}, it specifies a function of one |
| 1410 | argument that decides which file names are acceptable completion |
| 1411 | alternatives. A file name is an acceptable value if @var{predicate} |
| 1412 | returns non-@code{nil} for it. |
| 1413 | |
| 1414 | Here is an example of using @code{read-file-name}: |
| 1415 | |
| 1416 | @example |
| 1417 | @group |
| 1418 | (read-file-name "The file is ") |
| 1419 | |
| 1420 | ;; @r{After evaluation of the preceding expression,} |
| 1421 | ;; @r{the following appears in the minibuffer:} |
| 1422 | @end group |
| 1423 | |
| 1424 | @group |
| 1425 | ---------- Buffer: Minibuffer ---------- |
| 1426 | The file is /gp/gnu/elisp/@point{} |
| 1427 | ---------- Buffer: Minibuffer ---------- |
| 1428 | @end group |
| 1429 | @end example |
| 1430 | |
| 1431 | @noindent |
| 1432 | Typing @kbd{manual @key{TAB}} results in the following: |
| 1433 | |
| 1434 | @example |
| 1435 | @group |
| 1436 | ---------- Buffer: Minibuffer ---------- |
| 1437 | The file is /gp/gnu/elisp/manual.texi@point{} |
| 1438 | ---------- Buffer: Minibuffer ---------- |
| 1439 | @end group |
| 1440 | @end example |
| 1441 | |
| 1442 | @c Wordy to avoid overfull hbox in smallbook mode. |
| 1443 | @noindent |
| 1444 | If the user types @key{RET}, @code{read-file-name} returns the file name |
| 1445 | as the string @code{"/gp/gnu/elisp/manual.texi"}. |
| 1446 | @end defun |
| 1447 | |
| 1448 | @defvar read-file-name-function |
| 1449 | If non-@code{nil}, this should be a function that accepts the same |
| 1450 | arguments as @code{read-file-name}. When @code{read-file-name} is |
| 1451 | called, it calls this function with the supplied arguments instead of |
| 1452 | doing its usual work. |
| 1453 | @end defvar |
| 1454 | |
| 1455 | @defopt read-file-name-completion-ignore-case |
| 1456 | If this variable is non-@code{nil}, @code{read-file-name} ignores case |
| 1457 | when performing completion. |
| 1458 | @end defopt |
| 1459 | |
| 1460 | @defun read-directory-name prompt &optional directory default require-match initial |
| 1461 | This function is like @code{read-file-name} but allows only directory |
| 1462 | names as completion alternatives. |
| 1463 | |
| 1464 | If @var{default} is @code{nil} and @var{initial} is non-@code{nil}, |
| 1465 | @code{read-directory-name} constructs a substitute default by |
| 1466 | combining @var{directory} (or the current buffer's default directory |
| 1467 | if @var{directory} is @code{nil}) and @var{initial}. If both |
| 1468 | @var{default} and @var{initial} are @code{nil}, this function uses |
| 1469 | @var{directory} as substitute default, or the current buffer's default |
| 1470 | directory if @var{directory} is @code{nil}. |
| 1471 | @end defun |
| 1472 | |
| 1473 | @defopt insert-default-directory |
| 1474 | This variable is used by @code{read-file-name}, and thus, indirectly, |
| 1475 | by most commands reading file names. (This includes all commands that |
| 1476 | use the code letters @samp{f} or @samp{F} in their interactive form. |
| 1477 | @xref{Interactive Codes,, Code Characters for interactive}.) Its |
| 1478 | value controls whether @code{read-file-name} starts by placing the |
| 1479 | name of the default directory in the minibuffer, plus the initial file |
| 1480 | name, if any. If the value of this variable is @code{nil}, then |
| 1481 | @code{read-file-name} does not place any initial input in the |
| 1482 | minibuffer (unless you specify initial input with the @var{initial} |
| 1483 | argument). In that case, the default directory is still used for |
| 1484 | completion of relative file names, but is not displayed. |
| 1485 | |
| 1486 | If this variable is @code{nil} and the initial minibuffer contents are |
| 1487 | empty, the user may have to explicitly fetch the next history element |
| 1488 | to access a default value. If the variable is non-@code{nil}, the |
| 1489 | initial minibuffer contents are always non-empty and the user can |
| 1490 | always request a default value by immediately typing @key{RET} in an |
| 1491 | unedited minibuffer. (See above.) |
| 1492 | |
| 1493 | For example: |
| 1494 | |
| 1495 | @example |
| 1496 | @group |
| 1497 | ;; @r{Here the minibuffer starts out with the default directory.} |
| 1498 | (let ((insert-default-directory t)) |
| 1499 | (read-file-name "The file is ")) |
| 1500 | @end group |
| 1501 | |
| 1502 | @group |
| 1503 | ---------- Buffer: Minibuffer ---------- |
| 1504 | The file is ~lewis/manual/@point{} |
| 1505 | ---------- Buffer: Minibuffer ---------- |
| 1506 | @end group |
| 1507 | |
| 1508 | @group |
| 1509 | ;; @r{Here the minibuffer is empty and only the prompt} |
| 1510 | ;; @r{appears on its line.} |
| 1511 | (let ((insert-default-directory nil)) |
| 1512 | (read-file-name "The file is ")) |
| 1513 | @end group |
| 1514 | |
| 1515 | @group |
| 1516 | ---------- Buffer: Minibuffer ---------- |
| 1517 | The file is @point{} |
| 1518 | ---------- Buffer: Minibuffer ---------- |
| 1519 | @end group |
| 1520 | @end example |
| 1521 | @end defopt |
| 1522 | |
| 1523 | @defun read-shell-command prompt &optional initial history &rest args |
| 1524 | This function reads a shell command from the minibuffer, prompting |
| 1525 | with @var{prompt} and providing intelligent completion. It completes |
| 1526 | the first word of the command using candidates that are appropriate |
| 1527 | for command names, and the rest of the command words as file names. |
| 1528 | |
| 1529 | This function uses @code{minibuffer-local-shell-command-map} as the |
| 1530 | keymap for minibuffer input. The @var{history} argument specifies the |
| 1531 | history list to use; if is omitted or @code{nil}, it defaults to |
| 1532 | @code{shell-command-history} (@pxref{Minibuffer History, |
| 1533 | shell-command-history}). The optional argument @var{initial} |
| 1534 | specifies the initial content of the minibuffer (@pxref{Initial |
| 1535 | Input}). The rest of @var{args}, if present, are used as the |
| 1536 | @var{default} and @var{inherit-input-method} arguments in |
| 1537 | @code{read-from-minibuffer} (@pxref{Text from Minibuffer}). |
| 1538 | @end defun |
| 1539 | |
| 1540 | @defvar minibuffer-local-shell-command-map |
| 1541 | This keymap is used by @code{read-shell-command} for completing |
| 1542 | command and file names that are part of a shell command. It uses |
| 1543 | @code{minibuffer-local-map} as its parent keymap, and binds @key{TAB} |
| 1544 | to @code{completion-at-point}. |
| 1545 | @end defvar |
| 1546 | |
| 1547 | @node Completion Variables |
| 1548 | @subsection Completion Variables |
| 1549 | |
| 1550 | Here are some variables that can be used to alter the default |
| 1551 | completion behavior. |
| 1552 | |
| 1553 | @cindex completion styles |
| 1554 | @defopt completion-styles |
| 1555 | The value of this variable is a list of completion style (symbols) to |
| 1556 | use for performing completion. A @dfn{completion style} is a set of |
| 1557 | rules for generating completions. Each symbol occurring this list |
| 1558 | must have a corresponding entry in @code{completion-styles-alist}. |
| 1559 | @end defopt |
| 1560 | |
| 1561 | @defvar completion-styles-alist |
| 1562 | This variable stores a list of available completion styles. Each |
| 1563 | element in the list has the form |
| 1564 | |
| 1565 | @example |
| 1566 | (@var{style} @var{try-completion} @var{all-completions} @var{doc}) |
| 1567 | @end example |
| 1568 | |
| 1569 | @noindent |
| 1570 | Here, @var{style} is the name of the completion style (a symbol), |
| 1571 | which may be used in the @code{completion-styles} variable to refer to |
| 1572 | this style; @var{try-completion} is the function that does the |
| 1573 | completion; @var{all-completions} is the function that lists the |
| 1574 | completions; and @var{doc} is a string describing the completion |
| 1575 | style. |
| 1576 | |
| 1577 | The @var{try-completion} and @var{all-completions} functions should |
| 1578 | each accept four arguments: @var{string}, @var{collection}, |
| 1579 | @var{predicate}, and @var{point}. The @var{string}, @var{collection}, |
| 1580 | and @var{predicate} arguments have the same meanings as in |
| 1581 | @code{try-completion} (@pxref{Basic Completion}), and the @var{point} |
| 1582 | argument is the position of point within @var{string}. Each function |
| 1583 | should return a non-@code{nil} value if it performed its job, and |
| 1584 | @code{nil} if it did not (e.g.@: if there is no way to complete |
| 1585 | @var{string} according to the completion style). |
| 1586 | |
| 1587 | When the user calls a completion command like |
| 1588 | @code{minibuffer-complete} (@pxref{Completion Commands}), Emacs looks |
| 1589 | for the first style listed in @code{completion-styles} and calls its |
| 1590 | @var{try-completion} function. If this function returns @code{nil}, |
| 1591 | Emacs moves to the next listed completion style and calls its |
| 1592 | @var{try-completion} function, and so on until one of the |
| 1593 | @var{try-completion} functions successfully performs completion and |
| 1594 | returns a non-@code{nil} value. A similar procedure is used for |
| 1595 | listing completions, via the @var{all-completions} functions. |
| 1596 | |
| 1597 | @xref{Completion Styles,,, emacs, The GNU Emacs Manual}, for a |
| 1598 | description of the available completion styles. |
| 1599 | @end defvar |
| 1600 | |
| 1601 | @defopt completion-category-overrides |
| 1602 | This variable specifies special completion styles and other completion |
| 1603 | behaviors to use when completing certain types of text. Its value |
| 1604 | should be an alist with elements of the form @code{(@var{category} |
| 1605 | . @var{alist})}. @var{category} is a symbol describing what is being |
| 1606 | completed; currently, the @code{buffer}, @code{file}, and |
| 1607 | @code{unicode-name} categories are defined, but others can be defined |
| 1608 | via specialized completion functions (@pxref{Programmed Completion}). |
| 1609 | @var{alist} is an association list describing how completion should |
| 1610 | behave for the corresponding category. The following alist keys are |
| 1611 | supported: |
| 1612 | |
| 1613 | @table @code |
| 1614 | @item styles |
| 1615 | The value should be a list of completion styles (symbols). |
| 1616 | |
| 1617 | @item cycle |
| 1618 | The value should be a value for @code{completion-cycle-threshold} |
| 1619 | (@pxref{Completion Options,,, emacs, The GNU Emacs Manual}) for this |
| 1620 | category. |
| 1621 | @end table |
| 1622 | |
| 1623 | @noindent |
| 1624 | Additional alist entries may be defined in the future. |
| 1625 | @end defopt |
| 1626 | |
| 1627 | @defvar completion-extra-properties |
| 1628 | This variable is used to specify extra properties of the current |
| 1629 | completion command. It is intended to be let-bound by specialized |
| 1630 | completion commands. Its value should be a list of property and value |
| 1631 | pairs. The following properties are supported: |
| 1632 | |
| 1633 | @table @code |
| 1634 | @item :annotation-function |
| 1635 | The value should be a function to add annotations in the completions |
| 1636 | buffer. This function must accept one argument, a completion, and |
| 1637 | should either return @code{nil} or a string to be displayed next to |
| 1638 | the completion. |
| 1639 | |
| 1640 | @item :exit-function |
| 1641 | The value should be a function to run after performing completion. |
| 1642 | The function should accept two arguments, @var{string} and |
| 1643 | @var{status}, where @var{string} is the text to which the field was |
| 1644 | completed, and @var{status} indicates what kind of operation happened: |
| 1645 | @code{finished} if text is now complete, @code{sole} if the text |
| 1646 | cannot be further completed but completion is not finished, or |
| 1647 | @code{exact} if the text is a valid completion but may be further |
| 1648 | completed. |
| 1649 | @end table |
| 1650 | @end defvar |
| 1651 | |
| 1652 | @node Programmed Completion |
| 1653 | @subsection Programmed Completion |
| 1654 | @cindex programmed completion |
| 1655 | |
| 1656 | Sometimes it is not possible or convenient to create an alist or |
| 1657 | an obarray containing all the intended possible completions ahead |
| 1658 | of time. In such a case, you can supply your own function to compute |
| 1659 | the completion of a given string. This is called @dfn{programmed |
| 1660 | completion}. Emacs uses programmed completion when completing file |
| 1661 | names (@pxref{File Name Completion}), among many other cases. |
| 1662 | |
| 1663 | To use this feature, pass a function as the @var{collection} |
| 1664 | argument to @code{completing-read}. The function |
| 1665 | @code{completing-read} arranges to pass your completion function along |
| 1666 | to @code{try-completion}, @code{all-completions}, and other basic |
| 1667 | completion functions, which will then let your function do all |
| 1668 | the work. |
| 1669 | |
| 1670 | The completion function should accept three arguments: |
| 1671 | |
| 1672 | @itemize @bullet |
| 1673 | @item |
| 1674 | The string to be completed. |
| 1675 | |
| 1676 | @item |
| 1677 | A predicate function with which to filter possible matches, or |
| 1678 | @code{nil} if none. The function should call the predicate for each |
| 1679 | possible match, and ignore the match if the predicate returns |
| 1680 | @code{nil}. |
| 1681 | |
| 1682 | @item |
| 1683 | A flag specifying the type of completion operation to perform. This |
| 1684 | is one of the following four values: |
| 1685 | |
| 1686 | @table @code |
| 1687 | @item nil |
| 1688 | This specifies a @code{try-completion} operation. The function should |
| 1689 | return @code{t} if the specified string is a unique and exact match; |
| 1690 | if there is more than one match, it should return the common substring |
| 1691 | of all matches (if the string is an exact match for one completion |
| 1692 | alternative but also matches other longer alternatives, the return |
| 1693 | value is the string); if there are no matches, it should return |
| 1694 | @code{nil}. |
| 1695 | |
| 1696 | @item t |
| 1697 | This specifies an @code{all-completions} operation. The function |
| 1698 | should return a list of all possible completions of the specified |
| 1699 | string. |
| 1700 | |
| 1701 | @item lambda |
| 1702 | This specifies a @code{test-completion} operation. The function |
| 1703 | should return @code{t} if the specified string is an exact match for |
| 1704 | some completion alternative; @code{nil} otherwise. |
| 1705 | |
| 1706 | @item (boundaries . @var{suffix}) |
| 1707 | This specifies a @code{completion-boundaries} operation. The function |
| 1708 | should return @code{(boundaries @var{start} . @var{end})}, where |
| 1709 | @var{start} is the position of the beginning boundary in the specified |
| 1710 | string, and @var{end} is the position of the end boundary in |
| 1711 | @var{suffix}. |
| 1712 | |
| 1713 | @item metadata |
| 1714 | This specifies a request for information about the state of the |
| 1715 | current completion. The function should return an alist, as described |
| 1716 | below. The alist may contain any number of elements. |
| 1717 | @end table |
| 1718 | |
| 1719 | @noindent |
| 1720 | If the flag has any other value, the completion function should return |
| 1721 | @code{nil}. |
| 1722 | @end itemize |
| 1723 | |
| 1724 | The following is a list of metadata entries that a completion function |
| 1725 | may return in response to a @code{metadata} flag argument: |
| 1726 | |
| 1727 | @table @code |
| 1728 | @item category |
| 1729 | The value should be a symbol describing what kind of text the |
| 1730 | completion function is trying to complete. If the symbol matches one |
| 1731 | of the keys in @code{completion-category-overrides}, the usual |
| 1732 | completion behavior is overridden. @xref{Completion Variables}. |
| 1733 | |
| 1734 | @item annotation-function |
| 1735 | The value should be a function for @dfn{annotating} completions. The |
| 1736 | function should take one argument, @var{string}, which is a possible |
| 1737 | completion. It should return a string, which is displayed after the |
| 1738 | completion @var{string} in the @file{*Completions*} buffer. |
| 1739 | |
| 1740 | @item display-sort-function |
| 1741 | The value should be a function for sorting completions. The function |
| 1742 | should take one argument, a list of completion strings, and return a |
| 1743 | sorted list of completion strings. It is allowed to alter the input |
| 1744 | list destructively. |
| 1745 | |
| 1746 | @item cycle-sort-function |
| 1747 | The value should be a function for sorting completions, when |
| 1748 | @code{completion-cycle-threshold} is non-@code{nil} and the user is |
| 1749 | cycling through completion alternatives. @xref{Completion Options,,, |
| 1750 | emacs, The GNU Emacs Manual}. Its argument list and return value are |
| 1751 | the same as for @code{display-sort-function}. |
| 1752 | @end table |
| 1753 | |
| 1754 | @defun completion-table-dynamic function |
| 1755 | This function is a convenient way to write a function that can act as |
| 1756 | a programmed completion function. The argument @var{function} should be |
| 1757 | a function that takes one argument, a string, and returns an alist of |
| 1758 | possible completions of it. You can think of |
| 1759 | @code{completion-table-dynamic} as a transducer between that interface |
| 1760 | and the interface for programmed completion functions. |
| 1761 | @end defun |
| 1762 | |
| 1763 | @node Completion in Buffers |
| 1764 | @subsection Completion in Ordinary Buffers |
| 1765 | @cindex inline completion |
| 1766 | |
| 1767 | @findex completion-at-point |
| 1768 | Although completion is usually done in the minibuffer, the |
| 1769 | completion facility can also be used on the text in ordinary Emacs |
| 1770 | buffers. In many major modes, in-buffer completion is performed by |
| 1771 | the @kbd{C-M-i} or @kbd{M-@key{TAB}} command, bound to |
| 1772 | @code{completion-at-point}. @xref{Symbol Completion,,, emacs, The GNU |
| 1773 | Emacs Manual}. This command uses the abnormal hook variable |
| 1774 | @code{completion-at-point-functions}: |
| 1775 | |
| 1776 | @defvar completion-at-point-functions |
| 1777 | The value of this abnormal hook should be a list of functions, which |
| 1778 | are used to compute a completion table for completing the text at |
| 1779 | point. It can be used by major modes to provide mode-specific |
| 1780 | completion tables (@pxref{Major Mode Conventions}). |
| 1781 | |
| 1782 | When the command @code{completion-at-point} runs, it calls the |
| 1783 | functions in the list one by one, without any argument. Each function |
| 1784 | should return @code{nil} if it is unable to produce a completion table |
| 1785 | for the text at point. Otherwise it should return a list of the form |
| 1786 | |
| 1787 | @example |
| 1788 | (@var{start} @var{end} @var{collection} . @var{props}) |
| 1789 | @end example |
| 1790 | |
| 1791 | @noindent |
| 1792 | @var{start} and @var{end} delimit the text to complete (which should |
| 1793 | enclose point). @var{collection} is a completion table for completing |
| 1794 | that text, in a form suitable for passing as the second argument to |
| 1795 | @code{try-completion} (@pxref{Basic Completion}); completion |
| 1796 | alternatives will be generated from this completion table in the usual |
| 1797 | way, via the completion styles defined in @code{completion-styles} |
| 1798 | (@pxref{Completion Variables}). @var{props} is a property list for |
| 1799 | additional information; any of the properties in |
| 1800 | @code{completion-extra-properties} are recognized (@pxref{Completion |
| 1801 | Variables}), as well as the following additional ones: |
| 1802 | |
| 1803 | @table @code |
| 1804 | @item :predicate |
| 1805 | The value should be a predicate that completion candidates need to |
| 1806 | satisfy. |
| 1807 | |
| 1808 | @item :exclusive |
| 1809 | If the value is @code{no}, then if the completion table fails to match |
| 1810 | the text at point, @code{completion-at-point} moves on to the |
| 1811 | next function in @code{completion-at-point-functions} instead of |
| 1812 | reporting a completion failure. |
| 1813 | @end table |
| 1814 | |
| 1815 | A function in @code{completion-at-point-functions} may also return a |
| 1816 | function. In that case, that returned function is called, with no |
| 1817 | argument, and it is entirely responsible for performing the |
| 1818 | completion. We discourage this usage; it is intended to help convert |
| 1819 | old code to using @code{completion-at-point}. |
| 1820 | |
| 1821 | The first function in @code{completion-at-point-functions} to return a |
| 1822 | non-@code{nil} value is used by @code{completion-at-point}. The |
| 1823 | remaining functions are not called. The exception to this is when |
| 1824 | there is an @code{:exclusive} specification, as described above. |
| 1825 | @end defvar |
| 1826 | |
| 1827 | The following function provides a convenient way to perform |
| 1828 | completion on an arbitrary stretch of text in an Emacs buffer: |
| 1829 | |
| 1830 | @defun completion-in-region start end collection &optional predicate |
| 1831 | This function completes the text in the current buffer between the |
| 1832 | positions @var{start} and @var{end}, using @var{collection}. The |
| 1833 | argument @var{collection} has the same meaning as in |
| 1834 | @code{try-completion} (@pxref{Basic Completion}). |
| 1835 | |
| 1836 | This function inserts the completion text directly into the current |
| 1837 | buffer. Unlike @code{completing-read} (@pxref{Minibuffer |
| 1838 | Completion}), it does not activate the minibuffer. |
| 1839 | |
| 1840 | For this function to work, point must be somewhere between @var{start} |
| 1841 | and @var{end}. |
| 1842 | @end defun |
| 1843 | |
| 1844 | |
| 1845 | @node Yes-or-No Queries |
| 1846 | @section Yes-or-No Queries |
| 1847 | @cindex asking the user questions |
| 1848 | @cindex querying the user |
| 1849 | @cindex yes-or-no questions |
| 1850 | |
| 1851 | This section describes functions used to ask the user a yes-or-no |
| 1852 | question. The function @code{y-or-n-p} can be answered with a single |
| 1853 | character; it is useful for questions where an inadvertent wrong answer |
| 1854 | will not have serious consequences. @code{yes-or-no-p} is suitable for |
| 1855 | more momentous questions, since it requires three or four characters to |
| 1856 | answer. |
| 1857 | |
| 1858 | If either of these functions is called in a command that was invoked |
| 1859 | using the mouse---more precisely, if @code{last-nonmenu-event} |
| 1860 | (@pxref{Command Loop Info}) is either @code{nil} or a list---then it |
| 1861 | uses a dialog box or pop-up menu to ask the question. Otherwise, it |
| 1862 | uses keyboard input. You can force use either of the mouse or of keyboard |
| 1863 | input by binding @code{last-nonmenu-event} to a suitable value around |
| 1864 | the call. |
| 1865 | |
| 1866 | Strictly speaking, @code{yes-or-no-p} uses the minibuffer and |
| 1867 | @code{y-or-n-p} does not; but it seems best to describe them together. |
| 1868 | |
| 1869 | @defun y-or-n-p prompt |
| 1870 | This function asks the user a question, expecting input in the echo |
| 1871 | area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the |
| 1872 | user types @kbd{n}. This function also accepts @key{SPC} to mean yes |
| 1873 | and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like |
| 1874 | @kbd{C-g}, because the question might look like a minibuffer and for |
| 1875 | that reason the user might try to use @kbd{C-]} to get out. The answer |
| 1876 | is a single character, with no @key{RET} needed to terminate it. Upper |
| 1877 | and lower case are equivalent. |
| 1878 | |
| 1879 | ``Asking the question'' means printing @var{prompt} in the echo area, |
| 1880 | followed by the string @w{@samp{(y or n) }}. If the input is not one of |
| 1881 | the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}}, |
| 1882 | @kbd{@key{DEL}}, or something that quits), the function responds |
| 1883 | @samp{Please answer y or n.}, and repeats the request. |
| 1884 | |
| 1885 | This function does not actually use the minibuffer, since it does not |
| 1886 | allow editing of the answer. It actually uses the echo area (@pxref{The |
| 1887 | Echo Area}), which uses the same screen space as the minibuffer. The |
| 1888 | cursor moves to the echo area while the question is being asked. |
| 1889 | |
| 1890 | The answers and their meanings, even @samp{y} and @samp{n}, are not |
| 1891 | hardwired. The keymap @code{query-replace-map} specifies them. |
| 1892 | @xref{Search and Replace}. |
| 1893 | |
| 1894 | In the following example, the user first types @kbd{q}, which is |
| 1895 | invalid. At the next prompt the user types @kbd{y}. |
| 1896 | |
| 1897 | @c Need an interactive example, because otherwise the return value |
| 1898 | @c obscures the display of the valid answer. |
| 1899 | @smallexample |
| 1900 | @group |
| 1901 | (defun ask () |
| 1902 | (interactive) |
| 1903 | (y-or-n-p "Do you need a lift? ")) |
| 1904 | |
| 1905 | ;; @r{After evaluation of the preceding definition, @kbd{M-x ask}} |
| 1906 | ;; @r{causes the following prompt to appear in the echo area:} |
| 1907 | @end group |
| 1908 | |
| 1909 | @group |
| 1910 | ---------- Echo area ---------- |
| 1911 | Do you need a lift? (y or n) |
| 1912 | ---------- Echo area ---------- |
| 1913 | @end group |
| 1914 | |
| 1915 | ;; @r{If the user then types @kbd{q}, the following appears:} |
| 1916 | |
| 1917 | @group |
| 1918 | ---------- Echo area ---------- |
| 1919 | Please answer y or n. Do you need a lift? (y or n) |
| 1920 | ---------- Echo area ---------- |
| 1921 | @end group |
| 1922 | |
| 1923 | ;; @r{When the user types a valid answer,} |
| 1924 | ;; @r{it is displayed after the question:} |
| 1925 | |
| 1926 | @group |
| 1927 | ---------- Echo area ---------- |
| 1928 | Do you need a lift? (y or n) y |
| 1929 | ---------- Echo area ---------- |
| 1930 | @end group |
| 1931 | @end smallexample |
| 1932 | |
| 1933 | @noindent |
| 1934 | We show successive lines of echo area messages, but only one actually |
| 1935 | appears on the screen at a time. |
| 1936 | @end defun |
| 1937 | |
| 1938 | @defun y-or-n-p-with-timeout prompt seconds default |
| 1939 | Like @code{y-or-n-p}, except that if the user fails to answer within |
| 1940 | @var{seconds} seconds, this function stops waiting and returns |
| 1941 | @var{default}. It works by setting up a timer; see @ref{Timers}. |
| 1942 | The argument @var{seconds} may be an integer or a floating point number. |
| 1943 | @end defun |
| 1944 | |
| 1945 | @defun yes-or-no-p prompt |
| 1946 | This function asks the user a question, expecting input in the |
| 1947 | minibuffer. It returns @code{t} if the user enters @samp{yes}, |
| 1948 | @code{nil} if the user types @samp{no}. The user must type @key{RET} to |
| 1949 | finalize the response. Upper and lower case are equivalent. |
| 1950 | |
| 1951 | @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area, |
| 1952 | followed by @w{@samp{(yes or no) }}. The user must type one of the |
| 1953 | expected responses; otherwise, the function responds @samp{Please answer |
| 1954 | yes or no.}, waits about two seconds and repeats the request. |
| 1955 | |
| 1956 | @code{yes-or-no-p} requires more work from the user than |
| 1957 | @code{y-or-n-p} and is appropriate for more crucial decisions. |
| 1958 | |
| 1959 | Here is an example: |
| 1960 | |
| 1961 | @smallexample |
| 1962 | @group |
| 1963 | (yes-or-no-p "Do you really want to remove everything? ") |
| 1964 | |
| 1965 | ;; @r{After evaluation of the preceding expression,} |
| 1966 | ;; @r{the following prompt appears,} |
| 1967 | ;; @r{with an empty minibuffer:} |
| 1968 | @end group |
| 1969 | |
| 1970 | @group |
| 1971 | ---------- Buffer: minibuffer ---------- |
| 1972 | Do you really want to remove everything? (yes or no) |
| 1973 | ---------- Buffer: minibuffer ---------- |
| 1974 | @end group |
| 1975 | @end smallexample |
| 1976 | |
| 1977 | @noindent |
| 1978 | If the user first types @kbd{y @key{RET}}, which is invalid because this |
| 1979 | function demands the entire word @samp{yes}, it responds by displaying |
| 1980 | these prompts, with a brief pause between them: |
| 1981 | |
| 1982 | @smallexample |
| 1983 | @group |
| 1984 | ---------- Buffer: minibuffer ---------- |
| 1985 | Please answer yes or no. |
| 1986 | Do you really want to remove everything? (yes or no) |
| 1987 | ---------- Buffer: minibuffer ---------- |
| 1988 | @end group |
| 1989 | @end smallexample |
| 1990 | @end defun |
| 1991 | |
| 1992 | @node Multiple Queries |
| 1993 | @section Asking Multiple Y-or-N Questions |
| 1994 | |
| 1995 | When you have a series of similar questions to ask, such as ``Do you |
| 1996 | want to save this buffer'' for each buffer in turn, you should use |
| 1997 | @code{map-y-or-n-p} to ask the collection of questions, rather than |
| 1998 | asking each question individually. This gives the user certain |
| 1999 | convenient facilities such as the ability to answer the whole series at |
| 2000 | once. |
| 2001 | |
| 2002 | @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area |
| 2003 | This function asks the user a series of questions, reading a |
| 2004 | single-character answer in the echo area for each one. |
| 2005 | |
| 2006 | The value of @var{list} specifies the objects to ask questions about. |
| 2007 | It should be either a list of objects or a generator function. If it is |
| 2008 | a function, it should expect no arguments, and should return either the |
| 2009 | next object to ask about, or @code{nil}, meaning to stop asking questions. |
| 2010 | |
| 2011 | The argument @var{prompter} specifies how to ask each question. If |
| 2012 | @var{prompter} is a string, the question text is computed like this: |
| 2013 | |
| 2014 | @example |
| 2015 | (format @var{prompter} @var{object}) |
| 2016 | @end example |
| 2017 | |
| 2018 | @noindent |
| 2019 | where @var{object} is the next object to ask about (as obtained from |
| 2020 | @var{list}). |
| 2021 | |
| 2022 | If not a string, @var{prompter} should be a function of one argument |
| 2023 | (the next object to ask about) and should return the question text. If |
| 2024 | the value is a string, that is the question to ask the user. The |
| 2025 | function can also return @code{t}, meaning do act on this object (and |
| 2026 | don't ask the user), or @code{nil}, meaning ignore this object (and don't |
| 2027 | ask the user). |
| 2028 | |
| 2029 | The argument @var{actor} says how to act on the answers that the user |
| 2030 | gives. It should be a function of one argument, and it is called with |
| 2031 | each object that the user says yes for. Its argument is always an |
| 2032 | object obtained from @var{list}. |
| 2033 | |
| 2034 | If the argument @var{help} is given, it should be a list of this form: |
| 2035 | |
| 2036 | @example |
| 2037 | (@var{singular} @var{plural} @var{action}) |
| 2038 | @end example |
| 2039 | |
| 2040 | @noindent |
| 2041 | where @var{singular} is a string containing a singular noun that |
| 2042 | describes the objects conceptually being acted on, @var{plural} is the |
| 2043 | corresponding plural noun, and @var{action} is a transitive verb |
| 2044 | describing what @var{actor} does. |
| 2045 | |
| 2046 | If you don't specify @var{help}, the default is @code{("object" |
| 2047 | "objects" "act on")}. |
| 2048 | |
| 2049 | Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or |
| 2050 | @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip |
| 2051 | that object; @kbd{!} to act on all following objects; @key{ESC} or |
| 2052 | @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on |
| 2053 | the current object and then exit; or @kbd{C-h} to get help. These are |
| 2054 | the same answers that @code{query-replace} accepts. The keymap |
| 2055 | @code{query-replace-map} defines their meaning for @code{map-y-or-n-p} |
| 2056 | as well as for @code{query-replace}; see @ref{Search and Replace}. |
| 2057 | |
| 2058 | You can use @var{action-alist} to specify additional possible answers |
| 2059 | and what they mean. It is an alist of elements of the form |
| 2060 | @code{(@var{char} @var{function} @var{help})}, each of which defines one |
| 2061 | additional answer. In this element, @var{char} is a character (the |
| 2062 | answer); @var{function} is a function of one argument (an object from |
| 2063 | @var{list}); @var{help} is a string. |
| 2064 | |
| 2065 | When the user responds with @var{char}, @code{map-y-or-n-p} calls |
| 2066 | @var{function}. If it returns non-@code{nil}, the object is considered |
| 2067 | ``acted upon'', and @code{map-y-or-n-p} advances to the next object in |
| 2068 | @var{list}. If it returns @code{nil}, the prompt is repeated for the |
| 2069 | same object. |
| 2070 | |
| 2071 | Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while |
| 2072 | prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it |
| 2073 | does not do that. |
| 2074 | |
| 2075 | If @code{map-y-or-n-p} is called in a command that was invoked using the |
| 2076 | mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command |
| 2077 | Loop Info}) is either @code{nil} or a list---then it uses a dialog box |
| 2078 | or pop-up menu to ask the question. In this case, it does not use |
| 2079 | keyboard input or the echo area. You can force use either of the mouse or |
| 2080 | of keyboard input by binding @code{last-nonmenu-event} to a suitable |
| 2081 | value around the call. |
| 2082 | |
| 2083 | The return value of @code{map-y-or-n-p} is the number of objects acted on. |
| 2084 | @end defun |
| 2085 | @c FIXME An example of this would be more useful than all the |
| 2086 | @c preceding examples of simple things. |
| 2087 | |
| 2088 | @node Reading a Password |
| 2089 | @section Reading a Password |
| 2090 | @cindex passwords, reading |
| 2091 | |
| 2092 | To read a password to pass to another program, you can use the |
| 2093 | function @code{read-passwd}. |
| 2094 | |
| 2095 | @defun read-passwd prompt &optional confirm default |
| 2096 | This function reads a password, prompting with @var{prompt}. It does |
| 2097 | not echo the password as the user types it; instead, it echoes @samp{.} |
| 2098 | for each character in the password. |
| 2099 | |
| 2100 | The optional argument @var{confirm}, if non-@code{nil}, says to read the |
| 2101 | password twice and insist it must be the same both times. If it isn't |
| 2102 | the same, the user has to type it over and over until the last two |
| 2103 | times match. |
| 2104 | |
| 2105 | The optional argument @var{default} specifies the default password to |
| 2106 | return if the user enters empty input. If @var{default} is @code{nil}, |
| 2107 | then @code{read-passwd} returns the null string in that case. |
| 2108 | @end defun |
| 2109 | |
| 2110 | @node Minibuffer Commands |
| 2111 | @section Minibuffer Commands |
| 2112 | |
| 2113 | This section describes some commands meant for use in the |
| 2114 | minibuffer. |
| 2115 | |
| 2116 | @deffn Command exit-minibuffer |
| 2117 | This command exits the active minibuffer. It is normally bound to |
| 2118 | keys in minibuffer local keymaps. |
| 2119 | @end deffn |
| 2120 | |
| 2121 | @deffn Command self-insert-and-exit |
| 2122 | This command exits the active minibuffer after inserting the last |
| 2123 | character typed on the keyboard (found in @code{last-command-event}; |
| 2124 | @pxref{Command Loop Info}). |
| 2125 | @end deffn |
| 2126 | |
| 2127 | @deffn Command previous-history-element n |
| 2128 | This command replaces the minibuffer contents with the value of the |
| 2129 | @var{n}th previous (older) history element. |
| 2130 | @end deffn |
| 2131 | |
| 2132 | @deffn Command next-history-element n |
| 2133 | This command replaces the minibuffer contents with the value of the |
| 2134 | @var{n}th more recent history element. |
| 2135 | @end deffn |
| 2136 | |
| 2137 | @deffn Command previous-matching-history-element pattern n |
| 2138 | This command replaces the minibuffer contents with the value of the |
| 2139 | @var{n}th previous (older) history element that matches @var{pattern} (a |
| 2140 | regular expression). |
| 2141 | @end deffn |
| 2142 | |
| 2143 | @deffn Command next-matching-history-element pattern n |
| 2144 | This command replaces the minibuffer contents with the value of the |
| 2145 | @var{n}th next (newer) history element that matches @var{pattern} (a |
| 2146 | regular expression). |
| 2147 | @end deffn |
| 2148 | |
| 2149 | @deffn Command previous-complete-history-element n |
| 2150 | This command replaces the minibuffer contents with the value of the |
| 2151 | @var{n}th previous (older) history element that completes the current |
| 2152 | contents of the minibuffer before the point. |
| 2153 | @end deffn |
| 2154 | |
| 2155 | @deffn Command next-complete-history-element n |
| 2156 | This command replaces the minibuffer contents with the value of the |
| 2157 | @var{n}th next (newer) history element that completes the current |
| 2158 | contents of the minibuffer before the point. |
| 2159 | @end deffn |
| 2160 | |
| 2161 | |
| 2162 | @node Minibuffer Windows |
| 2163 | @section Minibuffer Windows |
| 2164 | @cindex minibuffer windows |
| 2165 | |
| 2166 | These functions access and select minibuffer windows |
| 2167 | and test whether they are active. |
| 2168 | |
| 2169 | @defun active-minibuffer-window |
| 2170 | This function returns the currently active minibuffer window, or |
| 2171 | @code{nil} if there is none. |
| 2172 | @end defun |
| 2173 | |
| 2174 | @defun minibuffer-window &optional frame |
| 2175 | @anchor{Definition of minibuffer-window} |
| 2176 | This function returns the minibuffer window used for frame @var{frame}. |
| 2177 | If @var{frame} is @code{nil}, that stands for the current frame. Note |
| 2178 | that the minibuffer window used by a frame need not be part of that |
| 2179 | frame---a frame that has no minibuffer of its own necessarily uses some |
| 2180 | other frame's minibuffer window. |
| 2181 | @end defun |
| 2182 | |
| 2183 | @defun set-minibuffer-window window |
| 2184 | This function specifies @var{window} as the minibuffer window to use. |
| 2185 | This affects where the minibuffer is displayed if you put text in it |
| 2186 | without invoking the usual minibuffer commands. It has no effect on |
| 2187 | the usual minibuffer input functions because they all start by |
| 2188 | choosing the minibuffer window according to the current frame. |
| 2189 | @end defun |
| 2190 | |
| 2191 | @c Emacs 19 feature |
| 2192 | @defun window-minibuffer-p &optional window |
| 2193 | This function returns non-@code{nil} if @var{window} is a minibuffer |
| 2194 | window. |
| 2195 | @var{window} defaults to the selected window. |
| 2196 | @end defun |
| 2197 | |
| 2198 | It is not correct to determine whether a given window is a minibuffer by |
| 2199 | comparing it with the result of @code{(minibuffer-window)}, because |
| 2200 | there can be more than one minibuffer window if there is more than one |
| 2201 | frame. |
| 2202 | |
| 2203 | @defun minibuffer-window-active-p window |
| 2204 | This function returns non-@code{nil} if @var{window} is the currently |
| 2205 | active minibuffer window. |
| 2206 | @end defun |
| 2207 | |
| 2208 | @node Minibuffer Contents |
| 2209 | @section Minibuffer Contents |
| 2210 | |
| 2211 | These functions access the minibuffer prompt and contents. |
| 2212 | |
| 2213 | @defun minibuffer-prompt |
| 2214 | This function returns the prompt string of the currently active |
| 2215 | minibuffer. If no minibuffer is active, it returns @code{nil}. |
| 2216 | @end defun |
| 2217 | |
| 2218 | @defun minibuffer-prompt-end |
| 2219 | This function returns the current |
| 2220 | position of the end of the minibuffer prompt, if a minibuffer is |
| 2221 | current. Otherwise, it returns the minimum valid buffer position. |
| 2222 | @end defun |
| 2223 | |
| 2224 | @defun minibuffer-prompt-width |
| 2225 | This function returns the current display-width of the minibuffer |
| 2226 | prompt, if a minibuffer is current. Otherwise, it returns zero. |
| 2227 | @end defun |
| 2228 | |
| 2229 | @defun minibuffer-contents |
| 2230 | This function returns the editable |
| 2231 | contents of the minibuffer (that is, everything except the prompt) as |
| 2232 | a string, if a minibuffer is current. Otherwise, it returns the |
| 2233 | entire contents of the current buffer. |
| 2234 | @end defun |
| 2235 | |
| 2236 | @defun minibuffer-contents-no-properties |
| 2237 | This is like @code{minibuffer-contents}, except that it does not copy text |
| 2238 | properties, just the characters themselves. @xref{Text Properties}. |
| 2239 | @end defun |
| 2240 | |
| 2241 | @defun minibuffer-completion-contents |
| 2242 | This is like @code{minibuffer-contents}, except that it returns only |
| 2243 | the contents before point. That is the part that completion commands |
| 2244 | operate on. @xref{Minibuffer Completion}. |
| 2245 | @end defun |
| 2246 | |
| 2247 | @defun delete-minibuffer-contents |
| 2248 | This function erases the editable contents of the minibuffer (that is, |
| 2249 | everything except the prompt), if a minibuffer is current. Otherwise, |
| 2250 | it erases the entire current buffer. |
| 2251 | @end defun |
| 2252 | |
| 2253 | @node Recursive Mini |
| 2254 | @section Recursive Minibuffers |
| 2255 | @cindex recursive minibuffers |
| 2256 | |
| 2257 | These functions and variables deal with recursive minibuffers |
| 2258 | (@pxref{Recursive Editing}): |
| 2259 | |
| 2260 | @defun minibuffer-depth |
| 2261 | This function returns the current depth of activations of the |
| 2262 | minibuffer, a nonnegative integer. If no minibuffers are active, it |
| 2263 | returns zero. |
| 2264 | @end defun |
| 2265 | |
| 2266 | @defopt enable-recursive-minibuffers |
| 2267 | If this variable is non-@code{nil}, you can invoke commands (such as |
| 2268 | @code{find-file}) that use minibuffers even while the minibuffer window |
| 2269 | is active. Such invocation produces a recursive editing level for a new |
| 2270 | minibuffer. The outer-level minibuffer is invisible while you are |
| 2271 | editing the inner one. |
| 2272 | |
| 2273 | If this variable is @code{nil}, you cannot invoke minibuffer |
| 2274 | commands when the minibuffer window is active, not even if you switch to |
| 2275 | another window to do it. |
| 2276 | @end defopt |
| 2277 | |
| 2278 | @c Emacs 19 feature |
| 2279 | If a command name has a property @code{enable-recursive-minibuffers} |
| 2280 | that is non-@code{nil}, then the command can use the minibuffer to read |
| 2281 | arguments even if it is invoked from the minibuffer. A command can |
| 2282 | also achieve this by binding @code{enable-recursive-minibuffers} |
| 2283 | to @code{t} in the interactive declaration (@pxref{Using Interactive}). |
| 2284 | The minibuffer command @code{next-matching-history-element} (normally |
| 2285 | @kbd{M-s} in the minibuffer) does the latter. |
| 2286 | |
| 2287 | @node Minibuffer Misc |
| 2288 | @section Minibuffer Miscellany |
| 2289 | |
| 2290 | @defun minibufferp &optional buffer-or-name |
| 2291 | This function returns non-@code{nil} if @var{buffer-or-name} is a |
| 2292 | minibuffer. If @var{buffer-or-name} is omitted, it tests the current |
| 2293 | buffer. |
| 2294 | @end defun |
| 2295 | |
| 2296 | @defvar minibuffer-setup-hook |
| 2297 | This is a normal hook that is run whenever the minibuffer is entered. |
| 2298 | @xref{Hooks}. |
| 2299 | @end defvar |
| 2300 | |
| 2301 | @defvar minibuffer-exit-hook |
| 2302 | This is a normal hook that is run whenever the minibuffer is exited. |
| 2303 | @xref{Hooks}. |
| 2304 | @end defvar |
| 2305 | |
| 2306 | @defvar minibuffer-help-form |
| 2307 | @anchor{Definition of minibuffer-help-form} |
| 2308 | The current value of this variable is used to rebind @code{help-form} |
| 2309 | locally inside the minibuffer (@pxref{Help Functions}). |
| 2310 | @end defvar |
| 2311 | |
| 2312 | @defvar minibuffer-scroll-window |
| 2313 | @anchor{Definition of minibuffer-scroll-window} |
| 2314 | If the value of this variable is non-@code{nil}, it should be a window |
| 2315 | object. When the function @code{scroll-other-window} is called in the |
| 2316 | minibuffer, it scrolls this window. |
| 2317 | @end defvar |
| 2318 | |
| 2319 | @defun minibuffer-selected-window |
| 2320 | This function returns the window that was selected when the |
| 2321 | minibuffer was entered. If selected window is not a minibuffer |
| 2322 | window, it returns @code{nil}. |
| 2323 | @end defun |
| 2324 | |
| 2325 | @defopt max-mini-window-height |
| 2326 | This variable specifies the maximum height for resizing minibuffer |
| 2327 | windows. If a float, it specifies a fraction of the height of the |
| 2328 | frame. If an integer, it specifies a number of lines. |
| 2329 | @end defopt |
| 2330 | |
| 2331 | @vindex minibuffer-message-timeout |
| 2332 | @defun minibuffer-message string &rest args |
| 2333 | This function displays @var{string} temporarily at the end of the |
| 2334 | minibuffer text, for a few seconds, or until the next input event |
| 2335 | arrives, whichever comes first. The variable |
| 2336 | @code{minibuffer-message-timeout} specifies the number of seconds to |
| 2337 | wait in the absence of input. It defaults to 2. If @var{args} is |
| 2338 | non-@code{nil}, the actual message is obtained by passing @var{string} |
| 2339 | and @var{args} through @code{format}. @xref{Formatting Strings}. |
| 2340 | @end defun |
| 2341 | |
| 2342 | @deffn Command minibuffer-inactive-mode |
| 2343 | This is the major mode used in inactive minibuffers. It uses |
| 2344 | keymap @code{minibuffer-inactive-mode-map}. This can be useful |
| 2345 | if the minibuffer is in a separate frame. @xref{Minibuffers and Frames}. |
| 2346 | @end deffn |