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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
5e0c8a23 | 3 | @c Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc. |
cc6d0d2c RS |
4 | @c See the file elisp.texi for copying conditions. |
5 | @setfilename ../info/customize | |
6 | @node Customization, Loading, Macros, Top | |
7 | @chapter Writing Customization Definitions | |
8 | ||
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9 | This chapter describes how to declare user options for customization, |
10 | and also customization groups for classifying them. We use the term | |
11 | @dfn{customization item} to include both kinds of customization | |
12 | definitions---as well as face definitions (@pxref{Defining Faces}). | |
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13 | |
14 | @menu | |
15 | * Common Keywords:: | |
16 | * Group Definitions:: | |
17 | * Variable Definitions:: | |
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18 | * Customization Types:: |
19 | @end menu | |
20 | ||
21 | @node Common Keywords | |
8241495d | 22 | @section Common Item Keywords |
cc6d0d2c | 23 | |
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24 | All kinds of customization declarations (for variables and groups, and |
25 | for faces) accept keyword arguments for specifying various information. | |
26 | This section describes some keywords that apply to all kinds. | |
cc6d0d2c | 27 | |
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28 | All of these keywords, except @code{:tag}, can be used more than once |
29 | in a given item. Each use of the keyword has an independent effect. | |
30 | The keyword @code{:tag} is an exception because any given item can only | |
31 | display one name. | |
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32 | |
33 | @table @code | |
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34 | @item :tag @var{label} |
35 | Use @var{label}, a string, instead of the item's name, to label the item | |
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36 | in customization menus and buffers. |
37 | ||
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38 | @item :group @var{group} |
39 | Put this customization item in group @var{group}. When you use | |
40 | @code{:group} in a @code{defgroup}, it makes the new group a subgroup of | |
41 | @var{group}. | |
42 | ||
43 | If you use this keyword more than once, you can put a single item into | |
44 | more than one group. Displaying any of those groups will show this | |
8241495d | 45 | item. Please don't overdo this, since the result would be annoying. |
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46 | |
47 | @item :link @var{link-data} | |
48 | Include an external link after the documentation string for this item. | |
49 | This is a sentence containing an active field which references some | |
50 | other documentation. | |
51 | ||
52 | There are three alternatives you can use for @var{link-data}: | |
53 | ||
54 | @table @code | |
55 | @item (custom-manual @var{info-node}) | |
56 | Link to an Info node; @var{info-node} is a string which specifies the | |
57 | node name, as in @code{"(emacs)Top"}. The link appears as | |
58 | @samp{[manual]} in the customization buffer. | |
59 | ||
60 | @item (info-link @var{info-node}) | |
61 | Like @code{custom-manual} except that the link appears | |
62 | in the customization buffer with the Info node name. | |
63 | ||
64 | @item (url-link @var{url}) | |
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65 | Link to a web page; @var{url} is a string which specifies the @sc{url}. |
66 | The link appears in the customization buffer as @var{url}. | |
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67 | |
68 | @item (emacs-commentary-link @var{library}) | |
69 | Link to the commentary section of a library; @var{library} is a string | |
70 | which specifies the library name. | |
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71 | @end table |
72 | ||
73 | You can specify the text to use in the customization buffer by adding | |
74 | @code{:tag @var{name}} after the first element of the @var{link-data}; | |
75 | for example, @code{(info-link :tag "foo" "(emacs)Top")} makes a link to | |
76 | the Emacs manual which appears in the buffer as @samp{foo}. | |
77 | ||
78 | An item can have more than one external link; however, most items have | |
79 | none at all. | |
80 | ||
81 | @item :load @var{file} | |
82 | Load file @var{file} (a string) before displaying this customization | |
83 | item. Loading is done with @code{load-library}, and only if the file is | |
84 | not already loaded. | |
85 | ||
86 | @item :require @var{feature} | |
87 | Require feature @var{feature} (a symbol) when installing a value for | |
88 | this item (an option or a face) that was saved using the customization | |
89 | feature. This is done by calling @code{require}. | |
90 | ||
91 | The most common reason to use @code{:require} is when a variable enables | |
92 | a feature such as a minor mode, and just setting the variable won't have | |
93 | any effect unless the code which implements the mode is loaded. | |
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94 | @end table |
95 | ||
96 | @node Group Definitions | |
97 | @section Defining Custom Groups | |
98 | ||
969fe9b5 | 99 | Each Emacs Lisp package should have one main customization group which |
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100 | contains all the options, faces and other groups in the package. If the |
101 | package has a small number of options and faces, use just one group and | |
102 | put everything in it. When there are more than twelve or so options and | |
103 | faces, then you should structure them into subgroups, and put the | |
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104 | subgroups under the package's main customization group. It is OK to |
105 | put some of the options and faces in the package's main group alongside | |
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106 | the subgroups. |
107 | ||
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108 | The package's main or only group should be a member of one or more of |
109 | the standard customization groups. (To display the full list of them, | |
110 | use @kbd{M-x customize}.) Choose one or more of them (but not too | |
111 | many), and add your group to each of them using the @code{:group} | |
112 | keyword. | |
cc6d0d2c | 113 | |
969fe9b5 | 114 | The way to declare new customization groups is with @code{defgroup}. |
cc6d0d2c | 115 | |
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116 | @defmac defgroup group members doc [keyword value]... |
117 | Declare @var{group} as a customization group containing @var{members}. | |
118 | Do not quote the symbol @var{group}. The argument @var{doc} specifies | |
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119 | the documentation string for the group. It should not start with a |
120 | @samp{*} as in @code{defcustom}; that convention is for variables only. | |
cc6d0d2c | 121 | |
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122 | The argument @var{members} is a list specifying an initial set of |
123 | customization items to be members of the group. However, most often | |
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124 | @var{members} is @code{nil}, and you specify the group's members by |
125 | using the @code{:group} keyword when defining those members. | |
cc6d0d2c | 126 | |
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127 | If you want to specify group members through @var{members}, each element |
128 | should have the form @code{(@var{name} @var{widget})}. Here @var{name} | |
129 | is a symbol, and @var{widget} is a widget type for editing that symbol. | |
130 | Useful widgets are @code{custom-variable} for a variable, | |
131 | @code{custom-face} for a face, and @code{custom-group} for a group. | |
cc6d0d2c | 132 | |
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133 | When a new group is introduced into Emacs, use this keyword in |
134 | @code{defgroup}: | |
135 | ||
136 | @table @code | |
137 | @item :version @var{version} | |
138 | This option specifies that the group was first introduced in Emacs | |
139 | version @var{version}. The value @var{version} must be a string. | |
140 | @end table | |
141 | ||
142 | Tag the group with a version like this when it is introduced, rather | |
143 | than the individual members (@pxref{Variable Definitions}). | |
144 | ||
cc6d0d2c | 145 | In addition to the common keywords (@pxref{Common Keywords}), you can |
3d66f910 | 146 | also use this keyword in @code{defgroup}: |
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147 | |
148 | @table @code | |
149 | @item :prefix @var{prefix} | |
150 | If the name of an item in the group starts with @var{prefix}, then the | |
151 | tag for that item is constructed (by default) by omitting @var{prefix}. | |
152 | ||
153 | One group can have any number of prefixes. | |
154 | @end table | |
155 | @end defmac | |
156 | ||
969fe9b5 RS |
157 | The prefix-discarding feature is currently turned off, which means |
158 | that @code{:prefix} currently has no effect. We did this because we | |
159 | found that discarding the specified prefixes often led to confusing | |
160 | names for options. This happened because the people who wrote the | |
161 | @code{defgroup} definitions for various groups added @code{:prefix} | |
162 | keywords whenever they make logical sense---that is, whenever the | |
163 | variables in the library have a common prefix. | |
164 | ||
165 | In order to obtain good results with @code{:prefix}, it would be | |
166 | necessary to check the specific effects of discarding a particular | |
167 | prefix, given the specific items in a group and their names and | |
168 | documentation. If the resulting text is not clear, then @code{:prefix} | |
169 | should not be used in that case. | |
170 | ||
171 | It should be possible to recheck all the customization groups, delete | |
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172 | the @code{:prefix} specifications which give unclear results, and then |
173 | turn this feature back on, if someone would like to do the work. | |
174 | ||
175 | @node Variable Definitions | |
176 | @section Defining Customization Variables | |
177 | ||
969fe9b5 | 178 | Use @code{defcustom} to declare user-editable variables. |
cc6d0d2c | 179 | |
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180 | @defmac defcustom option default doc [keyword value]... |
181 | Declare @var{option} as a customizable user option variable. Do not | |
182 | quote @var{option}. The argument @var{doc} specifies the documentation | |
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183 | string for the variable; it should normally start with a @samp{*}. This |
184 | marks the variable, for other purposes, as one that users may want to | |
185 | customize. | |
969fe9b5 RS |
186 | |
187 | If @var{option} is void, @code{defcustom} initializes it to | |
188 | @var{default}. @var{default} should be an expression to compute the | |
a9f0a989 | 189 | value; be careful in writing it, because it can be evaluated on more |
cc6d0d2c | 190 | than one occasion. |
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191 | |
192 | When you evaluate a @code{defcustom} form with @kbd{C-M-x} in Emacs Lisp | |
193 | mode (@code{eval-defun}), a special feature of @code{eval-defun} | |
194 | arranges to set the variable unconditionally, without testing whether | |
195 | its value is void. (The same feature applies to @code{defvar}.) | |
196 | @xref{Defining Variables}. | |
7dd3d99f | 197 | @end defmac |
cc6d0d2c | 198 | |
7dd3d99f | 199 | @code{defcustom} accepts the following additional keywords: |
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200 | |
201 | @table @code | |
202 | @item :type @var{type} | |
203 | Use @var{type} as the data type for this option. It specifies which | |
204 | values are legitimate, and how to display the value. | |
205 | @xref{Customization Types}, for more information. | |
206 | ||
207 | @item :options @var{list} | |
208 | Specify @var{list} as the list of reasonable values for use in this | |
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209 | option. The user is not restricted to using only these values, but they |
210 | are offered as convenient alternatives. | |
cc6d0d2c | 211 | |
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212 | This is meaningful only for certain types, currently including |
213 | @code{hook}, @code{plist} and @code{alist}. See the definition of the | |
214 | individual types for a description of how to use @code{:options}. | |
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215 | |
216 | @item :version @var{version} | |
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217 | This option specifies that the variable was first introduced, or its |
218 | default value was changed, in Emacs version @var{version}. The value | |
219 | @var{version} must be a string. For example, | |
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220 | |
221 | @example | |
222 | (defcustom foo-max 34 | |
223 | "*Maximum number of foo's allowed." | |
224 | :type 'integer | |
225 | :group 'foo | |
226 | :version "20.3") | |
227 | @end example | |
228 | ||
229 | @item :set @var{setfunction} | |
230 | Specify @var{setfunction} as the way to change the value of this option. | |
231 | The function @var{setfunction} should take two arguments, a symbol and | |
232 | the new value, and should do whatever is necessary to update the value | |
233 | properly for this option (which may not mean simply setting the option | |
234 | as a Lisp variable). The default for @var{setfunction} is | |
235 | @code{set-default}. | |
236 | ||
237 | @item :get @var{getfunction} | |
238 | Specify @var{getfunction} as the way to extract the value of this | |
239 | option. The function @var{getfunction} should take one argument, a | |
240 | symbol, and should return the ``current value'' for that symbol (which | |
241 | need not be the symbol's Lisp value). The default is | |
242 | @code{default-value}. | |
243 | ||
244 | @item :initialize @var{function} | |
245 | @var{function} should be a function used to initialize the variable when | |
246 | the @code{defcustom} is evaluated. It should take two arguments, the | |
247 | symbol and value. Here are some predefined functions meant for use in | |
248 | this way: | |
249 | ||
250 | @table @code | |
251 | @item custom-initialize-set | |
969fe9b5 RS |
252 | Use the variable's @code{:set} function to initialize the variable, but |
253 | do not reinitialize it if it is already non-void. This is the default | |
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254 | @code{:initialize} function. |
255 | ||
256 | @item custom-initialize-default | |
969fe9b5 RS |
257 | Like @code{custom-initialize-set}, but use the function |
258 | @code{set-default} to set the variable, instead of the variable's | |
259 | @code{:set} function. This is the usual choice for a variable whose | |
260 | @code{:set} function enables or disables a minor mode; with this choice, | |
261 | defining the variable will not call the minor mode function, but | |
262 | customizing the variable will do so. | |
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263 | |
264 | @item custom-initialize-reset | |
969fe9b5 RS |
265 | Always use the @code{:set} function to initialize the variable. If the |
266 | variable is already non-void, reset it by calling the @code{:set} | |
267 | function using the current value (returned by the @code{:get} method). | |
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268 | |
269 | @item custom-initialize-changed | |
969fe9b5 RS |
270 | Use the @code{:set} function to initialize the variable, if it is |
271 | already set or has been customized; otherwise, just use | |
272 | @code{set-default}. | |
cc6d0d2c | 273 | @end table |
390538c3 RS |
274 | |
275 | @item :set-after @var{variables} | |
276 | When setting variables according to saved customizations, make sure to | |
277 | set the variables @var{variables} before this one; in other words, delay | |
278 | setting this variable until after those others have been handled. Use | |
279 | @code{:set-after} if setting this variable won't work properly unless | |
280 | those other variables already have their intended values. | |
969fe9b5 | 281 | @end table |
cc6d0d2c | 282 | |
969fe9b5 | 283 | The @code{:require} option is useful for an option that turns on the |
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284 | operation of a certain feature. Assuming that the package is coded to |
285 | check the value of the option, you still need to arrange for the package | |
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286 | to be loaded. You can do that with @code{:require}. @xref{Common |
287 | Keywords}. Here is an example, from the library @file{paren.el}: | |
288 | ||
289 | @example | |
290 | (defcustom show-paren-mode nil | |
29b677db | 291 | "Toggle Show Paren mode..." |
969fe9b5 | 292 | :set (lambda (symbol value) |
a9f0a989 | 293 | (show-paren-mode (or value 0))) |
969fe9b5 RS |
294 | :initialize 'custom-initialize-default |
295 | :type 'boolean | |
296 | :group 'paren-showing | |
297 | :require 'paren) | |
298 | @end example | |
cc6d0d2c | 299 | |
b6954afd RS |
300 | If a customization item has a type such as @code{hook} or @code{alist}, |
301 | which supports @code{:options}, you can add additional options to the | |
302 | item, outside the @code{defcustom} declaration, by calling | |
303 | @code{custom-add-option}. For example, if you define a function | |
304 | @code{my-lisp-mode-initialization} intended to be called from | |
305 | @code{emacs-lisp-mode-hook}, you might want to add that to the list of | |
306 | options for @code{emacs-lisp-mode-hook}, but not by editing its | |
307 | definition. You can do it thus: | |
308 | ||
309 | @example | |
8241495d RS |
310 | (custom-add-option 'emacs-lisp-mode-hook |
311 | 'my-lisp-mode-initialization) | |
b6954afd | 312 | @end example |
cc6d0d2c RS |
313 | |
314 | @defun custom-add-option symbol option | |
b6954afd | 315 | To the customization @var{symbol}, add @var{option}. |
cc6d0d2c | 316 | |
b6954afd RS |
317 | The precise effect of adding @var{option} depends on the customization |
318 | type of @var{symbol}. | |
cc6d0d2c | 319 | @end defun |
cc6d0d2c RS |
320 | |
321 | Internally, @code{defcustom} uses the symbol property | |
322 | @code{standard-value} to record the expression for the default value, | |
323 | and @code{saved-value} to record the value saved by the user with the | |
324 | customization buffer. The @code{saved-value} property is actually a | |
325 | list whose car is an expression which evaluates to the value. | |
326 | ||
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327 | @node Customization Types |
328 | @section Customization Types | |
329 | ||
330 | When you define a user option with @code{defcustom}, you must specify | |
969fe9b5 | 331 | its @dfn{customization type}. That is a Lisp object which describes (1) |
cc6d0d2c RS |
332 | which values are legitimate and (2) how to display the value in the |
333 | customization buffer for editing. | |
334 | ||
335 | You specify the customization type in @code{defcustom} with the | |
336 | @code{:type} keyword. The argument of @code{:type} is evaluated; since | |
969fe9b5 | 337 | types that vary at run time are rarely useful, normally you use a quoted |
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338 | constant. For example: |
339 | ||
340 | @example | |
341 | (defcustom diff-command "diff" | |
342 | "*The command to use to run diff." | |
969fe9b5 | 343 | :type '(string) |
cc6d0d2c RS |
344 | :group 'diff) |
345 | @end example | |
346 | ||
969fe9b5 RS |
347 | In general, a customization type is a list whose first element is a |
348 | symbol, one of the customization type names defined in the following | |
349 | sections. After this symbol come a number of arguments, depending on | |
350 | the symbol. Between the type symbol and its arguments, you can | |
351 | optionally write keyword-value pairs (@pxref{Type Keywords}). | |
cc6d0d2c | 352 | |
969fe9b5 RS |
353 | Some of the type symbols do not use any arguments; those are called |
354 | @dfn{simple types}. For a simple type, if you do not use any | |
355 | keyword-value pairs, you can omit the parentheses around the type | |
356 | symbol. For example just @code{string} as a customization type is | |
357 | equivalent to @code{(string)}. | |
cc6d0d2c RS |
358 | |
359 | @menu | |
360 | * Simple Types:: | |
361 | * Composite Types:: | |
362 | * Splicing into Lists:: | |
363 | * Type Keywords:: | |
364 | @end menu | |
365 | ||
366 | @node Simple Types | |
367 | @subsection Simple Types | |
368 | ||
369 | This section describes all the simple customization types. | |
370 | ||
371 | @table @code | |
372 | @item sexp | |
373 | The value may be any Lisp object that can be printed and read back. You | |
374 | can use @code{sexp} as a fall-back for any option, if you don't want to | |
375 | take the time to work out a more specific type to use. | |
376 | ||
377 | @item integer | |
378 | The value must be an integer, and is represented textually | |
379 | in the customization buffer. | |
380 | ||
381 | @item number | |
382 | The value must be a number, and is represented textually in the | |
383 | customization buffer. | |
384 | ||
385 | @item string | |
386 | The value must be a string, and the customization buffer shows just the | |
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387 | contents, with no delimiting @samp{"} characters and no quoting with |
388 | @samp{\}. | |
cc6d0d2c RS |
389 | |
390 | @item regexp | |
969fe9b5 RS |
391 | Like @code{string} except that the string must be a valid regular |
392 | expression. | |
cc6d0d2c RS |
393 | |
394 | @item character | |
395 | The value must be a character code. A character code is actually an | |
396 | integer, but this type shows the value by inserting the character in the | |
397 | buffer, rather than by showing the number. | |
398 | ||
399 | @item file | |
400 | The value must be a file name, and you can do completion with | |
401 | @kbd{M-@key{TAB}}. | |
402 | ||
403 | @item (file :must-match t) | |
404 | The value must be a file name for an existing file, and you can do | |
405 | completion with @kbd{M-@key{TAB}}. | |
406 | ||
407 | @item directory | |
408 | The value must be a directory name, and you can do completion with | |
409 | @kbd{M-@key{TAB}}. | |
410 | ||
a9f0a989 RS |
411 | @item hook |
412 | The value must be a list of functions (or a single function, but that is | |
413 | obsolete usage). This customization type is used for hook variables. | |
1911e6e5 RS |
414 | You can use the @code{:options} keyword in a hook variable's |
415 | @code{defcustom} to specify a list of functions recommended for use in | |
416 | the hook; see @ref{Variable Definitions}. | |
a9f0a989 | 417 | |
b6954afd | 418 | @item alist |
08f0f5e9 KH |
419 | The value must be a list of cons-cells, the @sc{car} of each cell |
420 | representing a key, and the @sc{cdr} of the same cell representing an | |
421 | associated value. The user can add and delete key/value pairs, and | |
b6954afd RS |
422 | edit both the key and the value of each pair. |
423 | ||
424 | You can specify the key and value types like this: | |
425 | ||
8241495d RS |
426 | @smallexample |
427 | (alist :key-type @var{key-type} :value-type @var{value-type}) | |
428 | @end smallexample | |
b6954afd RS |
429 | |
430 | @noindent | |
431 | where @var{key-type} and @var{value-type} are customization type | |
432 | specifications. The default key type is @code{sexp}, and the default | |
433 | value type is @code{sexp}. | |
434 | ||
435 | The user can add any key matching the specified key type, but you can | |
436 | give some keys a preferential treatment by specifying them with the | |
437 | @code{:options} (see @ref{Variable Definitions}). The specified keys | |
438 | will always be shown in the customize buffer (together with a suitable | |
439 | value), with a checkbox to include or exclude or disable the key/value | |
440 | pair from the alist. The user will not be able to edit the keys | |
441 | specified by the @code{:options} keyword argument. | |
442 | ||
443 | The argument to the @code{:options} keywords should be a list of option | |
444 | specifications. Ordinarily, the options are simply atoms, which are the | |
445 | specified keys. For example: | |
446 | ||
8241495d | 447 | @smallexample |
b6954afd | 448 | :options '("foo" "bar" "baz") |
8241495d | 449 | @end smallexample |
b6954afd RS |
450 | |
451 | @noindent | |
452 | specifies that there are three ``known'' keys, namely @code{"foo"}, | |
453 | @code{"bar"} and @code{"baz"}, which will always be shown first. | |
454 | ||
455 | You may want to restrict the value type for specific keys, for example, | |
456 | the value associated with the @code{"bar"} key can only be an integer. | |
457 | You can specify this by using a list instead of an atom in the option | |
458 | specification. The first element will specify the key, like before, | |
459 | while the second element will specify the value type. | |
460 | ||
8241495d | 461 | @smallexample |
b6954afd | 462 | :options '("foo" ("bar" integer) "baz") |
8241495d | 463 | @end smallexample |
b6954afd RS |
464 | |
465 | Finally, you may want to change how the key is presented. By default, | |
466 | the key is simply shown as a @code{const}, since the user cannot change | |
467 | the special keys specified with the @code{:options} keyword. However, | |
468 | you may want to use a more specialized type for presenting the key, like | |
469 | @code{function-item} if you know it is a symbol with a function binding. | |
470 | This is done by using a customization type specification instead of a | |
471 | symbol for the key. | |
472 | ||
8241495d | 473 | @smallexample |
b6954afd | 474 | :options '("foo" ((function-item some-function) integer) "baz") |
8241495d | 475 | @end smallexample |
b6954afd | 476 | |
08f0f5e9 | 477 | Many alists use lists with two elements, instead of cons cells. For |
b6954afd RS |
478 | example, |
479 | ||
8241495d | 480 | @smallexample |
b6954afd RS |
481 | (defcustom list-alist '(("foo" 1) ("bar" 2) ("baz" 3)) |
482 | "Each element is a list of the form (KEY VALUE).") | |
8241495d | 483 | @end smallexample |
b6954afd RS |
484 | |
485 | @noindent | |
486 | instead of | |
487 | ||
8241495d | 488 | @smallexample |
b6954afd RS |
489 | (defcustom cons-alist '(("foo" . 1) ("bar" . 2) ("baz" . 3)) |
490 | "Each element is a cons-cell (KEY . VALUE).") | |
8241495d | 491 | @end smallexample |
b6954afd RS |
492 | |
493 | Because of the way lists are implemented on top of cons cells, you can | |
494 | treat @code{list-alist} in the example above as a cons cell alist, where | |
495 | the value type is a list with a single element containing the real | |
496 | value. | |
497 | ||
8241495d | 498 | @smallexample |
b6954afd RS |
499 | (defcustom list-alist '(("foo" 1) ("bar" 2) ("baz" 3)) |
500 | "Each element is a list of the form (KEY VALUE)." | |
501 | :type '(alist :value-type (group integer))) | |
8241495d | 502 | @end smallexample |
b6954afd RS |
503 | |
504 | The @code{group} widget is used here instead of @code{list} only because | |
505 | the formatting is better suited for the purpose. | |
506 | ||
507 | Similarily, you can have alists with more values associated with each | |
508 | key, using variations of this trick: | |
509 | ||
8241495d | 510 | @smallexample |
b6954afd RS |
511 | (defcustom person-data '(("brian" 50 t) |
512 | ("dorith" 55 nil) | |
513 | ("ken" 52 t)) | |
3d3df9e1 RS |
514 | "Alist of basic info about people. |
515 | Each element has the form (NAME AGE MALE-FLAG)." | |
b6954afd RS |
516 | :type '(alist :value-type (group age boolean))) |
517 | ||
518 | (defcustom pets '(("brian") | |
519 | ("dorith" "dog" "guppy") | |
520 | ("ken" "cat")) | |
3d3df9e1 RS |
521 | "Alist of people's pets. |
522 | In an element (KEY . VALUE), KEY is the person's name, | |
523 | and the VALUE is a list of that person's pets." | |
b6954afd | 524 | :type '(alist :value-type (repeat string))) |
8241495d | 525 | @end smallexample |
b6954afd RS |
526 | |
527 | @item plist | |
528 | The @code{plist} custom type is similar to the @code{alist} (see above), | |
529 | except that the information is stored as a property list, i.e. a list of | |
530 | this form: | |
531 | ||
8241495d | 532 | @smallexample |
b6954afd | 533 | (@var{key} @var{value} @var{key} @var{value} @var{key} @var{value} @dots{}) |
8241495d | 534 | @end smallexample |
b6954afd RS |
535 | |
536 | The default @code{:key-type} for @code{plist} is @code{symbol}, | |
537 | rather than @code{sexp}. | |
538 | ||
cc6d0d2c RS |
539 | @item symbol |
540 | The value must be a symbol. It appears in the customization buffer as | |
541 | the name of the symbol. | |
542 | ||
543 | @item function | |
544 | The value must be either a lambda expression or a function name. When | |
545 | it is a function name, you can do completion with @kbd{M-@key{TAB}}. | |
546 | ||
547 | @item variable | |
548 | The value must be a variable name, and you can do completion with | |
549 | @kbd{M-@key{TAB}}. | |
550 | ||
a9f0a989 RS |
551 | @item face |
552 | The value must be a symbol which is a face name, and you can do | |
553 | completion with @kbd{M-@key{TAB}}. | |
554 | ||
cc6d0d2c | 555 | @item boolean |
969fe9b5 RS |
556 | The value is boolean---either @code{nil} or @code{t}. Note that by |
557 | using @code{choice} and @code{const} together (see the next section), | |
558 | you can specify that the value must be @code{nil} or @code{t}, but also | |
559 | specify the text to describe each value in a way that fits the specific | |
560 | meaning of the alternative. | |
5e0c8a23 DL |
561 | |
562 | @item coding-system | |
563 | The value must be a coding-system name, and you can do completion with | |
564 | @kbd{M-@key{TAB}}. | |
565 | ||
566 | @item color | |
567 | The value must be a valid color name, and you can do completion with | |
568 | @kbd{M-@key{TAB}}. A sample is provided, | |
cc6d0d2c RS |
569 | @end table |
570 | ||
571 | @node Composite Types | |
572 | @subsection Composite Types | |
573 | ||
574 | When none of the simple types is appropriate, you can use composite | |
969fe9b5 RS |
575 | types, which build new types from other types. Here are several ways of |
576 | doing that: | |
cc6d0d2c RS |
577 | |
578 | @table @code | |
579 | @item (restricted-sexp :match-alternatives @var{criteria}) | |
580 | The value may be any Lisp object that satisfies one of @var{criteria}. | |
a9f0a989 | 581 | @var{criteria} should be a list, and each element should be |
cc6d0d2c RS |
582 | one of these possibilities: |
583 | ||
584 | @itemize @bullet | |
585 | @item | |
a9f0a989 RS |
586 | A predicate---that is, a function of one argument that has no side |
587 | effects, and returns either @code{nil} or non-@code{nil} according to | |
588 | the argument. Using a predicate in the list says that objects for which | |
589 | the predicate returns non-@code{nil} are acceptable. | |
cc6d0d2c RS |
590 | |
591 | @item | |
a9f0a989 RS |
592 | A quoted constant---that is, @code{'@var{object}}. This sort of element |
593 | in the list says that @var{object} itself is an acceptable value. | |
cc6d0d2c RS |
594 | @end itemize |
595 | ||
596 | For example, | |
597 | ||
598 | @example | |
a9f0a989 RS |
599 | (restricted-sexp :match-alternatives |
600 | (integerp 't 'nil)) | |
cc6d0d2c RS |
601 | @end example |
602 | ||
603 | @noindent | |
604 | allows integers, @code{t} and @code{nil} as legitimate values. | |
605 | ||
606 | The customization buffer shows all legitimate values using their read | |
607 | syntax, and the user edits them textually. | |
608 | ||
609 | @item (cons @var{car-type} @var{cdr-type}) | |
610 | The value must be a cons cell, its @sc{car} must fit @var{car-type}, and | |
a9f0a989 | 611 | its @sc{cdr} must fit @var{cdr-type}. For example, @code{(cons string |
cc6d0d2c RS |
612 | symbol)} is a customization type which matches values such as |
613 | @code{("foo" . foo)}. | |
614 | ||
969fe9b5 | 615 | In the customization buffer, the @sc{car} and the @sc{cdr} are |
cc6d0d2c RS |
616 | displayed and edited separately, each according to the type |
617 | that you specify for it. | |
618 | ||
619 | @item (list @var{element-types}@dots{}) | |
620 | The value must be a list with exactly as many elements as the | |
621 | @var{element-types} you have specified; and each element must fit the | |
622 | corresponding @var{element-type}. | |
623 | ||
624 | For example, @code{(list integer string function)} describes a list of | |
625 | three elements; the first element must be an integer, the second a | |
626 | string, and the third a function. | |
627 | ||
a9f0a989 | 628 | In the customization buffer, each element is displayed and edited |
cc6d0d2c RS |
629 | separately, according to the type specified for it. |
630 | ||
631 | @item (vector @var{element-types}@dots{}) | |
632 | Like @code{list} except that the value must be a vector instead of a | |
633 | list. The elements work the same as in @code{list}. | |
634 | ||
635 | @item (choice @var{alternative-types}...) | |
636 | The value must fit at least one of @var{alternative-types}. | |
637 | For example, @code{(choice integer string)} allows either an | |
638 | integer or a string. | |
639 | ||
640 | In the customization buffer, the user selects one of the alternatives | |
641 | using a menu, and can then edit the value in the usual way for that | |
642 | alternative. | |
643 | ||
644 | Normally the strings in this menu are determined automatically from the | |
645 | choices; however, you can specify different strings for the menu by | |
646 | including the @code{:tag} keyword in the alternatives. For example, if | |
647 | an integer stands for a number of spaces, while a string is text to use | |
648 | verbatim, you might write the customization type this way, | |
649 | ||
a9f0a989 | 650 | @example |
cc6d0d2c RS |
651 | (choice (integer :tag "Number of spaces") |
652 | (string :tag "Literal text")) | |
a9f0a989 | 653 | @end example |
cc6d0d2c RS |
654 | |
655 | @noindent | |
656 | so that the menu offers @samp{Number of spaces} and @samp{Literal Text}. | |
657 | ||
969fe9b5 RS |
658 | In any alternative for which @code{nil} is not a valid value, other than |
659 | a @code{const}, you should specify a valid default for that alternative | |
660 | using the @code{:value} keyword. @xref{Type Keywords}. | |
661 | ||
cc6d0d2c RS |
662 | @item (const @var{value}) |
663 | The value must be @var{value}---nothing else is allowed. | |
664 | ||
665 | The main use of @code{const} is inside of @code{choice}. For example, | |
666 | @code{(choice integer (const nil))} allows either an integer or | |
969fe9b5 RS |
667 | @code{nil}. |
668 | ||
669 | @code{:tag} is often used with @code{const}, inside of @code{choice}. | |
670 | For example, | |
671 | ||
a9f0a989 | 672 | @example |
969fe9b5 RS |
673 | (choice (const :tag "Yes" t) |
674 | (const :tag "No" nil) | |
675 | (const :tag "Ask" foo)) | |
a9f0a989 | 676 | @end example |
cc6d0d2c | 677 | |
da03dc1d RS |
678 | @noindent |
679 | describes a variable for which @code{t} means yes, @code{nil} means no, | |
680 | and @code{foo} means ``ask.'' | |
681 | ||
682 | @item (other @var{value}) | |
683 | This alternative can match any Lisp value, but if the user chooses this | |
684 | alternative, that selects the value @var{value}. | |
685 | ||
686 | The main use of @code{other} is as the last element of @code{choice}. | |
687 | For example, | |
688 | ||
689 | @example | |
690 | (choice (const :tag "Yes" t) | |
691 | (const :tag "No" nil) | |
692 | (other :tag "Ask" foo)) | |
693 | @end example | |
694 | ||
695 | @noindent | |
696 | describes a variable for which @code{t} means yes, @code{nil} means no, | |
697 | and anything else means ``ask.'' If the user chooses @samp{Ask} from | |
698 | the menu of alternatives, that specifies the value @code{foo}; but any | |
699 | other value (not @code{t}, @code{nil} or @code{foo}) displays as | |
700 | @samp{Ask}, just like @code{foo}. | |
701 | ||
cc6d0d2c RS |
702 | @item (function-item @var{function}) |
703 | Like @code{const}, but used for values which are functions. This | |
969fe9b5 RS |
704 | displays the documentation string as well as the function name. |
705 | The documentation string is either the one you specify with | |
706 | @code{:doc}, or @var{function}'s own documentation string. | |
cc6d0d2c RS |
707 | |
708 | @item (variable-item @var{variable}) | |
709 | Like @code{const}, but used for values which are variable names. This | |
969fe9b5 RS |
710 | displays the documentation string as well as the variable name. The |
711 | documentation string is either the one you specify with @code{:doc}, or | |
712 | @var{variable}'s own documentation string. | |
cc6d0d2c | 713 | |
1f447a50 KH |
714 | @item (set @var{types}@dots{}) |
715 | The value must be a list, and each element of the list must match one of | |
716 | the @var{types} specified. | |
717 | ||
718 | This appears in the customization buffer as a checklist, so that each of | |
719 | @var{types} may have either one corresponding element or none. It is | |
720 | not possible to specify two different elements that match the same one | |
721 | of @var{types}. For example, @code{(set integer symbol)} allows one | |
722 | integer and/or one symbol in the list; it does not allow multiple | |
723 | integers or multiple symbols. As a result, it is rare to use | |
724 | nonspecific types such as @code{integer} in a @code{set}. | |
725 | ||
726 | Most often, the @var{types} in a @code{set} are @code{const} types, as | |
727 | shown here: | |
728 | ||
729 | @example | |
730 | (set (const :bold) (const :italic)) | |
731 | @end example | |
732 | ||
733 | Sometimes they describe possible elements in an alist: | |
734 | ||
735 | @example | |
736 | (set (cons :tag "Height" (const height) integer) | |
737 | (cons :tag "Width" (const width) integer)) | |
738 | @end example | |
739 | ||
740 | @noindent | |
741 | That lets the user specify a height value optionally | |
742 | and a width value optionally. | |
cc6d0d2c RS |
743 | |
744 | @item (repeat @var{element-type}) | |
745 | The value must be a list and each element of the list must fit the type | |
746 | @var{element-type}. This appears in the customization buffer as a | |
747 | list of elements, with @samp{[INS]} and @samp{[DEL]} buttons for adding | |
748 | more elements or removing elements. | |
749 | @end table | |
750 | ||
751 | @node Splicing into Lists | |
752 | @subsection Splicing into Lists | |
753 | ||
754 | The @code{:inline} feature lets you splice a variable number of | |
755 | elements into the middle of a list or vector. You use it in a | |
756 | @code{set}, @code{choice} or @code{repeat} type which appears among the | |
757 | element-types of a @code{list} or @code{vector}. | |
758 | ||
759 | Normally, each of the element-types in a @code{list} or @code{vector} | |
760 | describes one and only one element of the list or vector. Thus, if an | |
761 | element-type is a @code{repeat}, that specifies a list of unspecified | |
762 | length which appears as one element. | |
763 | ||
764 | But when the element-type uses @code{:inline}, the value it matches is | |
765 | merged directly into the containing sequence. For example, if it | |
766 | matches a list with three elements, those become three elements of the | |
767 | overall sequence. This is analogous to using @samp{,@@} in the backquote | |
768 | construct. | |
769 | ||
770 | For example, to specify a list whose first element must be @code{t} | |
771 | and whose remaining arguments should be zero or more of @code{foo} and | |
772 | @code{bar}, use this customization type: | |
773 | ||
774 | @example | |
775 | (list (const t) (set :inline t foo bar)) | |
776 | @end example | |
777 | ||
778 | @noindent | |
779 | This matches values such as @code{(t)}, @code{(t foo)}, @code{(t bar)} | |
780 | and @code{(t foo bar)}. | |
781 | ||
782 | When the element-type is a @code{choice}, you use @code{:inline} not | |
783 | in the @code{choice} itself, but in (some of) the alternatives of the | |
784 | @code{choice}. For example, to match a list which must start with a | |
785 | file name, followed either by the symbol @code{t} or two strings, use | |
786 | this customization type: | |
787 | ||
788 | @example | |
789 | (list file | |
790 | (choice (const t) | |
791 | (list :inline t string string))) | |
792 | @end example | |
793 | ||
794 | @noindent | |
795 | If the user chooses the first alternative in the choice, then the | |
796 | overall list has two elements and the second element is @code{t}. If | |
797 | the user chooses the second alternative, then the overall list has three | |
798 | elements and the second and third must be strings. | |
799 | ||
800 | @node Type Keywords | |
801 | @subsection Type Keywords | |
802 | ||
803 | You can specify keyword-argument pairs in a customization type after the | |
804 | type name symbol. Here are the keywords you can use, and their | |
805 | meanings: | |
806 | ||
807 | @table @code | |
808 | @item :value @var{default} | |
809 | This is used for a type that appears as an alternative inside of | |
969fe9b5 | 810 | @code{choice}; it specifies the default value to use, at first, if and |
cc6d0d2c RS |
811 | when the user selects this alternative with the menu in the |
812 | customization buffer. | |
813 | ||
814 | Of course, if the actual value of the option fits this alternative, it | |
815 | will appear showing the actual value, not @var{default}. | |
816 | ||
969fe9b5 RS |
817 | If @code{nil} is not a valid value for the alternative, then it is |
818 | essential to specify a valid default with @code{:value}. | |
819 | ||
cc6d0d2c RS |
820 | @item :format @var{format-string} |
821 | This string will be inserted in the buffer to represent the value | |
822 | corresponding to the type. The following @samp{%} escapes are available | |
823 | for use in @var{format-string}: | |
824 | ||
825 | @table @samp | |
cc6d0d2c RS |
826 | @item %[@var{button}%] |
827 | Display the text @var{button} marked as a button. The @code{:action} | |
828 | attribute specifies what the button will do if the user invokes it; | |
829 | its value is a function which takes two arguments---the widget which | |
830 | the button appears in, and the event. | |
831 | ||
832 | There is no way to specify two different buttons with different | |
969fe9b5 | 833 | actions. |
cc6d0d2c RS |
834 | |
835 | @item %@{@var{sample}%@} | |
836 | Show @var{sample} in a special face specified by @code{:sample-face}. | |
837 | ||
838 | @item %v | |
839 | Substitute the item's value. How the value is represented depends on | |
840 | the kind of item, and (for variables) on the customization type. | |
841 | ||
842 | @item %d | |
843 | Substitute the item's documentation string. | |
844 | ||
845 | @item %h | |
846 | Like @samp{%d}, but if the documentation string is more than one line, | |
847 | add an active field to control whether to show all of it or just the | |
848 | first line. | |
849 | ||
850 | @item %t | |
851 | Substitute the tag here. You specify the tag with the @code{:tag} | |
852 | keyword. | |
853 | ||
854 | @item %% | |
855 | Display a literal @samp{%}. | |
856 | @end table | |
857 | ||
969fe9b5 RS |
858 | @item :action @var{action} |
859 | Perform @var{action} if the user clicks on a button. | |
860 | ||
cc6d0d2c | 861 | @item :button-face @var{face} |
969fe9b5 RS |
862 | Use the face @var{face} (a face name or a list of face names) for button |
863 | text displayed with @samp{%[@dots{}%]}. | |
cc6d0d2c | 864 | |
969fe9b5 RS |
865 | @item :button-prefix @var{prefix} |
866 | @itemx :button-suffix @var{suffix} | |
cc6d0d2c RS |
867 | These specify the text to display before and after a button. |
868 | Each can be: | |
869 | ||
870 | @table @asis | |
871 | @item @code{nil} | |
872 | No text is inserted. | |
873 | ||
874 | @item a string | |
875 | The string is inserted literally. | |
876 | ||
877 | @item a symbol | |
878 | The symbol's value is used. | |
879 | @end table | |
880 | ||
969fe9b5 RS |
881 | @item :tag @var{tag} |
882 | Use @var{tag} (a string) as the tag for the value (or part of the value) | |
883 | that corresponds to this type. | |
884 | ||
cc6d0d2c | 885 | @item :doc @var{doc} |
969fe9b5 RS |
886 | Use @var{doc} as the documentation string for this value (or part of the |
887 | value) that corresponds to this type. In order for this to work, you | |
888 | must specify a value for @code{:format}, and use @samp{%d} or @samp{%h} | |
889 | in that value. | |
cc6d0d2c | 890 | |
969fe9b5 RS |
891 | The usual reason to specify a documentation string for a type is to |
892 | provide more information about the meanings of alternatives inside a | |
893 | @code{:choice} type or the parts of some other composite type. | |
cc6d0d2c RS |
894 | |
895 | @item :help-echo @var{motion-doc} | |
896 | When you move to this item with @code{widget-forward} or | |
19182f77 DL |
897 | @code{widget-backward}, it will display the string @var{motion-doc} in |
898 | the echo area. In addition, @var{motion-doc} is used as the mouse | |
899 | @code{help-echo} string and may actually be a function or form evaluated | |
900 | to yield a help string as for @code{help-echo} text properties. | |
e23a63a5 | 901 | @c @xref{Text help-echo}. |
cc6d0d2c RS |
902 | |
903 | @item :match @var{function} | |
969fe9b5 RS |
904 | Specify how to decide whether a value matches the type. The |
905 | corresponding value, @var{function}, should be a function that accepts | |
906 | two arguments, a widget and a value; it should return non-@code{nil} if | |
907 | the value is acceptable. | |
cc6d0d2c RS |
908 | |
909 | @ignore | |
910 | @item :indent @var{columns} | |
911 | Indent this item by @var{columns} columns. The indentation is used for | |
912 | @samp{%n}, and automatically for group names, for checklists and radio | |
913 | buttons, and for editable lists. It affects the whole of the | |
914 | item except for the first line. | |
915 | ||
916 | @item :offset @var{columns} | |
917 | An integer indicating how many extra spaces to indent the subitems of | |
918 | this item. By default, subitems are indented the same as their parent. | |
919 | ||
920 | @item :extra-offset | |
921 | An integer indicating how many extra spaces to add to this item's | |
922 | indentation, compared to its parent. | |
923 | ||
924 | @item :notify | |
925 | A function called each time the item or a subitem is changed. The | |
926 | function is called with two or three arguments. The first argument is | |
927 | the item itself, the second argument is the item that was changed, and | |
928 | the third argument is the event leading to the change, if any. | |
929 | ||
930 | @item :menu-tag | |
931 | Tag used in the menu when the widget is used as an option in a | |
932 | @code{menu-choice} widget. | |
933 | ||
934 | @item :menu-tag-get | |
935 | Function used for finding the tag when the widget is used as an option | |
936 | in a @code{menu-choice} widget. By default, the tag used will be either the | |
937 | @code{:menu-tag} or @code{:tag} property if present, or the @code{princ} | |
938 | representation of the @code{:value} property if not. | |
939 | ||
940 | @item :validate | |
941 | A function which takes a widget as an argument, and return nil if the | |
942 | widgets current value is valid for the widget. Otherwise, it should | |
943 | return the widget containing the invalid data, and set that widgets | |
944 | @code{:error} property to a string explaining the error. | |
945 | ||
946 | You can use the function @code{widget-children-validate} for this job; | |
947 | it tests that all children of @var{widget} are valid. | |
948 | ||
949 | @item :tab-order | |
950 | Specify the order in which widgets are traversed with | |
951 | @code{widget-forward} or @code{widget-backward}. This is only partially | |
952 | implemented. | |
953 | ||
954 | @enumerate a | |
955 | @item | |
956 | Widgets with tabbing order @code{-1} are ignored. | |
957 | ||
958 | @item | |
959 | (Unimplemented) When on a widget with tabbing order @var{n}, go to the | |
960 | next widget in the buffer with tabbing order @var{n+1} or @code{nil}, | |
961 | whichever comes first. | |
962 | ||
963 | @item | |
964 | When on a widget with no tabbing order specified, go to the next widget | |
965 | in the buffer with a positive tabbing order, or @code{nil} | |
966 | @end enumerate | |
967 | ||
968 | @item :parent | |
a9f0a989 | 969 | The parent of a nested widget (e.g., a @code{menu-choice} item or an |
cc6d0d2c RS |
970 | element of a @code{editable-list} widget). |
971 | ||
972 | @item :sibling-args | |
973 | This keyword is only used for members of a @code{radio-button-choice} or | |
974 | @code{checklist}. The value should be a list of extra keyword | |
975 | arguments, which will be used when creating the @code{radio-button} or | |
976 | @code{checkbox} associated with this item. | |
977 | @end ignore | |
978 | @end table |