4 @setfilename ../info/widget
5 @settitle The Emacs Widget Library
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38 * Widget: (widget). The "widget" package used by the Emacs Customization
42 @node Top, Introduction, (dir), (dir)
43 @comment node-name, next, previous, up
44 @top The Emacs Widget Library
49 * Programming Example::
50 * Setting Up the Buffer::
54 * Defining New Widgets::
62 @node Introduction, User Interface, Top, Top
63 @comment node-name, next, previous, up
66 Most graphical user interface toolkits provide a number of standard
67 user interface controls (sometimes known as `widgets' or `gadgets').
68 Emacs doesn't really support anything like this, except for an
69 incredibly powerful text ``widget.'' On the other hand, Emacs does
70 provide the necessary primitives to implement many other widgets
71 within a text buffer. The @code{widget} package simplifies this task.
74 @cindex widgets, basic types
75 The basic widgets are:
79 Areas of text with an associated action. Intended for hypertext links
82 Like link, but intended for stand-alone buttons.
84 An editable text field. It can be either variable or fixed length.
86 Allows the user to choose one of multiple options from a menu, each
87 option is itself a widget. Only the selected option will be visible in
89 @item radio-button-choice
90 Allows the user to choose one of multiple options by activating radio
91 buttons. The options are implemented as widgets. All options will be
92 visible in the buffer.
94 A simple constant widget intended to be used in the @code{menu-choice} and
95 @code{radio-button-choice} widgets.
97 A button item only intended for use in choices. When invoked, the user
98 will be asked to select another option from the choice widget.
100 A simple @samp{on}/@samp{off} switch.
102 A checkbox (@samp{[ ]}/@samp{[X]}).
104 Create an editable list. The user can insert or delete items in the
105 list. Each list item is itself a widget.
108 Now, of what possible use can support for widgets be in a text editor?
109 I'm glad you asked. The answer is that widgets are useful for
110 implementing forms. A @dfn{form} in Emacs is a buffer where the user is
111 supposed to fill out a number of fields, each of which has a specific
112 meaning. The user is not supposed to change or delete any of the text
113 between the fields. Examples of forms in Emacs are the @file{forms}
114 package (of course), the customize buffers, the mail and news compose
115 modes, and the @acronym{HTML} form support in the @file{w3} browser.
117 @cindex widget library, why use it
118 The advantages for a programmer of using the @code{widget} package to
123 More complex fields than just editable text are supported.
125 You can give the users immediate feedback if they enter invalid data in a
126 text field, and sometimes prevent entering invalid data.
128 You can have fixed sized fields, thus allowing multiple fields to be
131 It is simple to query or set the value of a field.
133 Editing happens in the buffer, not in the mini-buffer.
135 Packages using the library get a uniform look, making them easier for
138 As support for embedded graphics improve, the widget library will be
139 extended to use the GUI features. This means that your code using the
140 widget library will also use the new graphic features automatically.
143 In order to minimize the code that is loaded by users who do not
144 create any widgets, the code has been split in two files:
146 @cindex widget library, files
149 This will declare the user variables, define the function
150 @code{define-widget}, and autoload the function @code{widget-create}.
152 Everything else is here, there is no reason to load it explicitly, as
153 it will be autoloaded when needed.
156 @node User Interface, Programming Example, Introduction, Top
157 @comment node-name, next, previous, up
158 @section User Interface
160 A form consist of read only text for documentation and some fields,
161 where each field contains two parts, a tag and a value. The tags are
162 used to identify the fields, so the documentation can refer to the
163 @samp{foo field}, meaning the field tagged with @samp{Foo}. Here is an
167 Here is some documentation.
169 Name: @i{My Name} @strong{Choose}: This option
170 Address: @i{Some Place
174 See also @b{_other work_} for more information.
176 Numbers: count to three below
177 @b{[INS]} @b{[DEL]} @i{One}
178 @b{[INS]} @b{[DEL]} @i{Eh, two?}
179 @b{[INS]} @b{[DEL]} @i{Five!}
194 @b{[Apply Form]} @b{[Reset Form]}
197 The top level widgets in is example are tagged @samp{Name},
198 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
199 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
200 @samp{[Reset Form]}. There are basically two things the user can do
201 within a form, namely editing the editable text fields and activating
204 @subsection Editable Text Fields
206 In the example, the value for the @samp{Name} is most likely displayed
207 in an editable text field, and so are values for each of the members of
208 the @samp{Numbers} list. All the normal Emacs editing operations are
209 available for editing these fields. The only restriction is that each
210 change you make must be contained within a single editable text field.
211 For example, capitalizing all text from the middle of one field to the
212 middle of another field is prohibited.
214 Editable text fields are created by the @code{editable-field} widget.
216 @strong{Warning:} In an @code{editable-field} widget, the editable
217 field must not be adjacent to another widget---that won't work.
218 You must put some text in between. Either make this text part of
219 the @code{editable-field} widget itself, or insert it with
220 @code{widget-insert}.
222 The @code{:format} keyword is useful for generating the necessary
223 text; for instance, if you give it a value of @code{"Name: %v "},
224 the @samp{Name: } part will provide the necessary separating text
225 before the field and the trailing space will provide the
226 separating text after the field. If you don't include the
227 @code{:size} keyword, the field will extend to the end of the
228 line, and the terminating newline will provide separation after.
230 The editing text fields are highlighted with the
231 @code{widget-field-face} face, making them easy to find.
233 @deffn Face widget-field-face
234 Face used for other editing fields.
239 @cindex widget buttons
240 @cindex button widgets
241 Some portions of the buffer have an associated @dfn{action}, which can
242 be @dfn{invoked} by a standard key or mouse command. These portions
243 are called @dfn{buttons}. The default commands for activating a button
248 @deffn Command widget-button-press @var{pos} &optional @var{event}
249 Invoke the button at @var{pos}, defaulting to point.
250 If point is not located on a button, invoke the binding in
251 @code{widget-global-map} (by default the global map).
254 @kindex Mouse-2 @r{(on button widgets})
256 @deffn Command widget-button-click @var{event}
257 Invoke the button at the location of the mouse pointer. If the mouse
258 pointer is located in an editable text field, invoke the binding in
259 @code{widget-global-map} (by default the global map).
263 There are several different kind of buttons, all of which are present in
267 @cindex option field tag
268 @item The Option Field Tags
269 When you invoke one of these buttons, you will be asked to choose
270 between a number of different options. This is how you edit an option
271 field. Option fields are created by the @code{menu-choice} widget. In
272 the example, @samp{@b{Choose}} is an option field tag.
273 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons
274 Activating these will insert or delete elements from an editable list.
275 The list is created by the @code{editable-list} widget.
276 @cindex embedded buttons
277 @item Embedded Buttons
278 The @samp{@b{_other work_}} is an example of an embedded
279 button. Embedded buttons are not associated with a fields, but can serve
280 any purpose, such as implementing hypertext references. They are
281 usually created by the @code{link} widget.
282 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons
283 Activating one of these will convert it to the other. This is useful
284 for implementing multiple-choice fields. You can create it with the
285 @code{checkbox} widget.
286 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons
287 Only one radio button in a @code{radio-button-choice} widget can be
288 selected at any time. When you invoke one of the unselected radio
289 buttons, it will be selected and the previous selected radio button will
291 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons
292 These are explicit buttons made with the @code{push-button} widget. The
293 main difference from the @code{link} widget is that the buttons will be
294 displayed as GUI buttons when possible.
297 To make them easier to locate, buttons are emphasized in the buffer.
299 @deffn Face widget-button-face
300 Face used for buttons.
303 @defopt widget-mouse-face
304 Face used for highlighting a button when the mouse pointer moves across
308 @subsection Navigation
310 You can use all the normal Emacs commands to move around in a form
311 buffer, plus you will have these additional commands:
315 @deffn Command widget-forward &optional count
316 Move point @var{count} buttons or editing fields forward.
318 @item @kbd{M-@key{TAB}}
319 @itemx @kbd{S-@key{TAB}}
320 @deffn Command widget-backward &optional count
321 Move point @var{count} buttons or editing fields backward.
325 @node Programming Example, Setting Up the Buffer, User Interface, Top
326 @comment node-name, next, previous, up
327 @section Programming Example
329 @cindex widgets, programming example
330 @cindex example of using widgets
331 Here is the code to implement the user interface example (@pxref{User
340 (defvar widget-example-repeat)
342 (defun widget-example ()
343 "Create the widgets from the Widget manual."
345 (switch-to-buffer "*Widget Example*")
346 (kill-all-local-variables)
347 (make-local-variable 'widget-example-repeat)
348 (let ((inhibit-read-only t))
351 (widget-insert "Here is some documentation.\n\nName: ")
352 (widget-create 'editable-field
354 :format "%v " ; Text after the field!
356 (widget-create 'menu-choice
359 :help-echo "Choose me, please!"
360 :notify (lambda (widget &rest ignore)
361 (message "%s is a good choice!"
362 (widget-value widget)))
363 '(item :tag "This option" :value "This")
364 '(choice-item "That option")
365 '(editable-field :menu-tag "No option" "Thus option"))
366 (widget-insert "Address: ")
367 (widget-create 'editable-field
368 "Some Place\nIn some City\nSome country.")
369 (widget-insert "\nSee also ")
371 :notify (lambda (&rest ignore)
372 (widget-value-set widget-example-repeat
377 " for more information.\n\nNumbers: count to three below\n")
378 (setq widget-example-repeat
379 (widget-create 'editable-list
380 :entry-format "%i %d %v"
381 :notify (lambda (widget &rest ignore)
382 (let ((old (widget-get widget
384 (new (length (widget-value widget))))
386 (widget-put widget ':example-length new)
387 (message "You can count to %d." new))))
388 :value '("One" "Eh, two?" "Five!")
389 '(editable-field :value "three")))
390 (widget-insert "\n\nSelect multiple:\n\n")
391 (widget-create 'checkbox t)
392 (widget-insert " This\n")
393 (widget-create 'checkbox nil)
394 (widget-insert " That\n")
395 (widget-create 'checkbox
396 :notify (lambda (&rest ignore) (message "Tickle"))
398 (widget-insert " Thus\n\nSelect one:\n\n")
399 (widget-create 'radio-button-choice
401 :notify (lambda (widget &rest ignore)
402 (message "You selected %s"
403 (widget-value widget)))
404 '(item "One") '(item "Another One.") '(item "A Final One."))
406 (widget-create 'push-button
407 :notify (lambda (&rest ignore)
408 (if (= (length (widget-value widget-example-repeat))
410 (message "Congratulation!")
411 (error "Three was the count!")))
414 (widget-create 'push-button
415 :notify (lambda (&rest ignore)
419 (use-local-map widget-keymap)
423 @node Setting Up the Buffer, Basic Types, Programming Example, Top
424 @comment node-name, next, previous, up
425 @section Setting Up the Buffer
427 Widgets are created with @code{widget-create}, which returns a
428 @dfn{widget} object. This object can be queried and manipulated by
429 other widget functions, until it is deleted with @code{widget-delete}.
430 After the widgets have been created, @code{widget-setup} must be called
433 @defun widget-create type [ keyword argument ]@dots{}
434 Create and return a widget of type @var{type}.
435 The syntax for the @var{type} argument is described in @ref{Basic Types}.
437 The keyword arguments can be used to overwrite the keyword arguments
438 that are part of @var{type}.
441 @defun widget-delete widget
442 Delete @var{widget} and remove it from the buffer.
446 Set up a buffer to support widgets.
448 This should be called after creating all the widgets and before allowing
449 the user to edit them.
453 If you want to insert text outside the widgets in the form, the
454 recommended way to do that is with @code{widget-insert}.
457 Insert the arguments, either strings or characters, at point.
458 The inserted text will be read-only.
461 There is a standard widget keymap which you might find useful.
463 @findex widget-button-press
464 @findex widget-button-click
465 @defvr Const widget-keymap
466 A keymap with the global keymap as its parent.@*
467 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
468 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
469 are bound to @code{widget-button-press} and
470 @code{widget-button-click}.@refill
473 @defvar widget-global-map
474 Keymap used by @code{widget-button-press} and @code{widget-button-click}
475 when not on a button. By default this is @code{global-map}.
478 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
479 @comment node-name, next, previous, up
482 The syntax of a type specification is given below:
485 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
489 Where, @var{name} is a widget name, @var{keyword} is the name of a
490 property, @var{argument} is the value of the property, and @var{args}
491 are interpreted in a widget specific way.
493 @cindex keyword arguments
494 The following keyword arguments that apply to all widgets:
497 @vindex value@r{ keyword}
499 The initial value for widgets of this type.
501 @vindex format@r{ keyword}
503 This string will be inserted in the buffer when you create a widget.
504 The following @samp{%} escapes are available:
509 The text inside will be marked as a button.
511 By default, the text will be shown in @code{widget-button-face}, and
512 surrounded by brackets.
514 @defopt widget-button-prefix
515 String to prefix buttons.
518 @defopt widget-button-suffix
519 String to suffix buttons.
524 The text inside will be displayed with the face specified by
528 This will be replaced with the buffer representation of the widget's
529 value. What this is depends on the widget type.
532 Insert the string specified by @code{:doc} here.
535 Like @samp{%d}, with the following modifications: If the documentation
536 string is more than one line, it will add a button which will toggle
537 between showing only the first line, and showing the full text.
538 Furthermore, if there is no @code{:doc} property in the widget, it will
539 instead examine the @code{:documentation-property} property. If it is a
540 lambda expression, it will be called with the widget's value as an
541 argument, and the result will be used as the documentation text.
544 Insert the string specified by @code{:tag} here, or the @code{princ}
545 representation of the value if there is no tag.
548 Insert a literal @samp{%}.
551 @vindex button-face@r{ keyword}
553 Face used to highlight text inside %[ %] in the format.
555 @vindex button-prefix@r{ keyword}
556 @vindex button-suffix@r{ keyword}
558 @itemx :button-suffix
559 Text around %[ %] in the format.
567 The string is inserted literally.
570 The value of the symbol is expanded according to this table.
573 @vindex doc@r{ keyword}
575 The string inserted by the @samp{%d} escape in the format
578 @vindex tag@r{ keyword}
580 The string inserted by the @samp{%t} escape in the format
583 @vindex tag-glyph@r{ keyword}
585 Name of image to use instead of the string specified by @code{:tag} on
586 Emacsen that supports it.
588 @vindex help-echo@r{ keyword}
590 Specifies how to display a message whenever you move to the widget with
591 either @code{widget-forward} or @code{widget-backward} or move the mouse
592 over it (using the standard @code{help-echo} mechanism). The argument
593 is either a string to display, a function of one argument, the widget,
594 which should return a string to display, or a form that evaluates to
597 @vindex follow-link@r{ keyword}
599 Specifies how to interpret a @key{mouse-1} click on the widget.
600 @xref{Links and Mouse-1,,, elisp, the Emacs Lisp Reference Manual}.
602 @vindex indent@r{ keyword}
604 An integer indicating the absolute number of spaces to indent children
607 @vindex offset@r{ keyword}
609 An integer indicating how many extra spaces to add to the widget's
610 grandchildren compared to this widget.
612 @vindex extra-offset@r{ keyword}
614 An integer indicating how many extra spaces to add to the widget's
615 children compared to this widget.
617 @vindex notify@r{ keyword}
619 A function called each time the widget or a nested widget is changed.
620 The function is called with two or three arguments. The first argument
621 is the widget itself, the second argument is the widget that was
622 changed, and the third argument is the event leading to the change, if
625 @vindex menu-tag@r{ keyword}
627 Tag used in the menu when the widget is used as an option in a
628 @code{menu-choice} widget.
630 @vindex menu-tag-get@r{ keyword}
632 Function used for finding the tag when the widget is used as an option
633 in a @code{menu-choice} widget. By default, the tag used will be either the
634 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
635 representation of the @code{:value} property if not.
637 @vindex match@r{ keyword}
639 Should be a function called with two arguments, the widget and a value,
640 and returning non-@code{nil} if the widget can represent the specified value.
642 @vindex validate@r{ keyword}
644 A function which takes a widget as an argument, and returns @code{nil}
645 if the widget's current value is valid for the widget. Otherwise it
646 should return the widget containing the invalid data, and set that
647 widget's @code{:error} property to a string explaining the error.
649 The following predefined function can be used:
651 @defun widget-children-validate widget
652 All the @code{:children} of @var{widget} must be valid.
655 @vindex tab-order@r{ keyword}
657 Specify the order in which widgets are traversed with
658 @code{widget-forward} or @code{widget-backward}. This is only partially
663 Widgets with tabbing order @code{-1} are ignored.
666 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
667 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
668 whichever comes first.
671 When on a widget with no tabbing order specified, go to the next widget
672 in the buffer with a positive tabbing order, or @code{nil}
675 @vindex parent@r{ keyword}
677 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
678 element of a @code{editable-list} widget).
680 @vindex sibling-args@r{ keyword}
682 This keyword is only used for members of a @code{radio-button-choice} or
683 @code{checklist}. The value should be a list of extra keyword
684 arguments, which will be used when creating the @code{radio-button} or
685 @code{checkbox} associated with this item.
689 @deffn {User Option} widget-glyph-directory
690 Directory where glyphs are found.
691 Widget will look here for a file with the same name as specified for the
692 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
695 @deffn{User Option} widget-glyph-enable
696 If non-@code{nil}, allow glyphs to appear on displays where they are supported.
708 * radio-button-choice::
718 @node link, url-link, Basic Types, Basic Types
719 @comment node-name, next, previous, up
720 @subsection The @code{link} Widget
721 @findex link@r{ widget}
726 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
729 The @var{value}, if present, is used to initialize the @code{:value}
730 property. The value should be a string, which will be inserted in the
733 By default the link will be shown in brackets.
735 @defopt widget-link-prefix
736 String to prefix links.
739 @defopt widget-link-suffix
740 String to suffix links.
743 @node url-link, info-link, link, Basic Types
744 @comment node-name, next, previous, up
745 @subsection The @code{url-link} Widget
746 @findex url-link@r{ widget}
751 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
754 @findex browse-url-browser-function@r{, and @code{url-link} widget}
755 When this link is invoked, the @acronym{WWW} browser specified by
756 @code{browse-url-browser-function} will be called with @var{url}.
758 @node info-link, push-button, url-link, Basic Types
759 @comment node-name, next, previous, up
760 @subsection The @code{info-link} Widget
761 @findex info-link@r{ widget}
766 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
769 When this link is invoked, the built-in Info reader is started on
772 @node push-button, editable-field, info-link, Basic Types
773 @comment node-name, next, previous, up
774 @subsection The @code{push-button} Widget
775 @findex push-button@r{ widget}
780 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
783 The @var{value}, if present, is used to initialize the @code{:value}
784 property. The value should be a string, which will be inserted in the
787 By default the tag will be shown in brackets.
789 @defopt widget-push-button-prefix
790 String to prefix push buttons.
793 @defopt widget-push-button-suffix
794 String to suffix push buttons.
797 @node editable-field, text, push-button, Basic Types
798 @comment node-name, next, previous, up
799 @subsection The @code{editable-field} Widget
800 @findex editable-field@r{ widget}
805 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
808 The @var{value}, if present, is used to initialize the @code{:value}
809 property. The value should be a string, which will be inserted in
810 field. This widget will match all string values.
812 The following extra properties are recognized:
815 @vindex size@r{ keyword}
817 The width of the editable field.@*
818 By default the field will reach to the end of the line.
820 @vindex value-face@r{ keyword}
822 Face used for highlighting the editable field. Default is
823 @code{widget-field-face}, see @ref{User Interface}.
825 @vindex secret@r{ keyword}
827 Character used to display the value. You can set this to e.g.@: @code{?*}
828 if the field contains a password or other secret information. By
829 default, this is @code{nil}, and the value is not secret.
831 @vindex valid-regexp@r{ keyword}
833 By default the @code{:validate} function will match the content of the
834 field with the value of this attribute. The default value is @code{""}
835 which matches everything.
837 @vindex keymap@r{ keyword}
838 @vindex widget-field-keymap
840 Keymap used in the editable field. The default value is
841 @code{widget-field-keymap}, which allows you to use all the normal
842 editing commands, even if the buffer's major mode suppresses some of
843 them. Pressing @key{RET} invokes the function specified by
847 @node text, menu-choice, editable-field, Basic Types
848 @comment node-name, next, previous, up
849 @subsection The @code{text} Widget
850 @findex text@r{ widget}
852 @vindex widget-text-keymap
853 This is just like @code{editable-field}, but intended for multiline text
854 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
855 does not rebind the @key{RET} key.
857 @node menu-choice, radio-button-choice, text, Basic Types
858 @comment node-name, next, previous, up
859 @subsection The @code{menu-choice} Widget
860 @findex menu-choice@r{ widget}
865 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
868 The @var{type} argument represents each possible choice. The widget's
869 value will be that of the chosen @var{type} argument. This widget will
870 match any value matching at least one of the specified @var{type}
874 @vindex void@r{ keyword}
876 Widget type used as a fallback when the value does not match any of the
877 specified @var{type} arguments.
879 @vindex case-fold@r{ keyword}
881 Set this to @code{nil} if you don't want to ignore case when prompting for a
882 choice through the minibuffer.
884 @vindex children@r{ keyword}
886 A list whose @sc{car} is the widget representing the currently chosen
889 @vindex choice@r{ keyword}
891 The current chosen type.
893 @vindex args@r{ keyword}
898 @node radio-button-choice, item, menu-choice, Basic Types
899 @comment node-name, next, previous, up
900 @subsection The @code{radio-button-choice} Widget
901 @findex radio-button-choice@r{ widget}
906 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
909 The @var{type} argument represents each possible choice. The widget's
910 value will be that of the chosen @var{type} argument. This widget will
911 match any value matching at least one of the specified @var{type}
914 The following extra properties are recognized.
917 @vindex entry-format@r{ keyword}
919 This string will be inserted for each entry in the list.
920 The following @samp{%} escapes are available:
923 Replace with the buffer representation of the @var{type} widget.
925 Replace with the radio button.
927 Insert a literal @samp{%}.
930 @vindex button-args@r{ keyword}
932 A list of keywords to pass to the radio buttons. Useful for setting
933 e.g.@: the @samp{:help-echo} for each button.
935 @vindex buttons@r{ keyword}
937 The widgets representing the radio buttons.
939 @vindex children@r{ keyword}
941 The widgets representing each type.
943 @vindex choice@r{ keyword}
945 The current chosen type
947 @vindex args@r{ keyword}
952 You can add extra radio button items to a @code{radio-button-choice}
953 widget after it has been created with the function
954 @code{widget-radio-add-item}.
956 @defun widget-radio-add-item widget type
957 Add to @code{radio-button-choice} widget @var{widget} a new radio button
958 item of type @var{type}.
961 Please note that such items added after the @code{radio-button-choice}
962 widget has been created will @strong{not} be properly destructed when
963 you call @code{widget-delete}.
965 @node item, choice-item, radio-button-choice, Basic Types
966 @comment node-name, next, previous, up
967 @subsection The @code{item} Widget
968 @findex item@r{ widget}
973 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
976 The @var{value}, if present, is used to initialize the @code{:value}
977 property. The value should be a string, which will be inserted in the
978 buffer. This widget will only match the specified value.
980 @node choice-item, toggle, item, Basic Types
981 @comment node-name, next, previous, up
982 @subsection The @code{choice-item} Widget
983 @findex choice-item@r{ widget}
988 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
991 The @var{value}, if present, is used to initialize the @code{:value}
992 property. The value should be a string, which will be inserted in the
993 buffer as a button. Activating the button of a @code{choice-item} is
994 equivalent to activating the parent widget. This widget will only match
997 @node toggle, checkbox, choice-item, Basic Types
998 @comment node-name, next, previous, up
999 @subsection The @code{toggle} Widget
1000 @findex toggle@r{ widget}
1005 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
1008 The widget has two possible states, @samp{on} and @samp{off}, which
1009 correspond to a @code{t} or @code{nil} value, respectively.
1011 The following extra properties are recognized:
1015 A string representing the @samp{on} state. By default the string
1018 A string representing the @samp{off} state. By default the string
1020 @vindex on-glyph@r{ keyword}
1022 Name of a glyph to be used instead of the @samp{:on} text string, on
1023 emacsen that supports this.
1024 @vindex off-glyph@r{ keyword}
1026 Name of a glyph to be used instead of the @samp{:off} text string, on
1027 emacsen that supports this.
1030 @node checkbox, checklist, toggle, Basic Types
1031 @comment node-name, next, previous, up
1032 @subsection The @code{checkbox} Widget
1033 @findex checkbox@r{ widget}
1035 This widget has two possible states, @samp{selected} and
1036 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1041 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1044 @node checklist, editable-list, checkbox, Basic Types
1045 @comment node-name, next, previous, up
1046 @subsection The @code{checklist} Widget
1047 @findex checklist@r{ widget}
1052 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1055 The @var{type} arguments represent each checklist item. The widget's
1056 value will be a list containing the values of all checked @var{type}
1057 arguments. The checklist widget will match a list whose elements all
1058 match at least one of the specified @var{type} arguments.
1060 The following extra properties are recognized:
1063 @vindex entry-format@r{ keyword}
1065 This string will be inserted for each entry in the list.
1066 The following @samp{%} escapes are available:
1069 Replaced with the buffer representation of the @var{type} widget.
1071 Replace with the checkbox.
1073 Insert a literal @samp{%}.
1076 @vindex greedy@r{ keyword}
1078 Usually a checklist will only match if the items are in the exact
1079 sequence given in the specification. By setting @code{:greedy} to
1080 non-@code{nil}, it will allow the items to come in any sequence.
1081 However, if you extract the value they will be in the sequence given
1082 in the checklist, i.e.@: the original sequence is forgotten.
1084 @vindex button-args@r{ keyword}
1086 A list of keywords to pass to the checkboxes. Useful for setting
1087 e.g.@: the @samp{:help-echo} for each checkbox.
1089 @vindex buttons@r{ keyword}
1091 The widgets representing the checkboxes.
1093 @vindex children@r{ keyword}
1095 The widgets representing each type.
1097 @vindex args@r{ keyword}
1102 @node editable-list, group, checklist, Basic Types
1103 @comment node-name, next, previous, up
1104 @subsection The @code{editable-list} Widget
1105 @findex editable-list@r{ widget}
1110 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1113 The value is a list, where each member represents one widget of type
1116 The following extra properties are recognized:
1119 @vindex entry-format@r{ keyword}
1121 This string will be inserted for each entry in the list.
1122 The following @samp{%} escapes are available:
1125 This will be replaced with the buffer representation of the @var{type}
1128 Insert the @b{[INS]} button.
1130 Insert the @b{[DEL]} button.
1132 Insert a literal @samp{%}.
1135 @vindex insert-button-args@r{ keyword}
1136 @item :insert-button-args
1137 A list of keyword arguments to pass to the insert buttons.
1139 @vindex delete-button-args@r{ keyword}
1140 @item :delete-button-args
1141 A list of keyword arguments to pass to the delete buttons.
1143 @vindex append-button-args@r{ keyword}
1144 @item :append-button-args
1145 A list of keyword arguments to pass to the trailing insert button.
1147 @vindex buttons@r{ keyword}
1149 The widgets representing the insert and delete buttons.
1151 @vindex children@r{ keyword}
1153 The widgets representing the elements of the list.
1155 @vindex args@r{ keyword}
1157 List whose @sc{car} is the type of the list elements.
1160 @node group, , editable-list, Basic Types
1161 @comment node-name, next, previous, up
1162 @subsection The @code{group} Widget
1163 @findex group@r{ widget}
1165 This widget simply group other widgets together.
1170 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1173 The value is a list, with one member for each @var{type}.
1175 @node Sexp Types, Widget Properties, Basic Types, Top
1180 A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
1181 for short, are also available. These basically fall in several
1182 categories described in this section.
1191 @node constants, generic, Sexp Types, Sexp Types
1192 @comment node-name, next, previous, up
1193 @subsection The Constant Widgets
1194 @cindex constant widgets
1196 The @code{const} widget can contain any Lisp expression, but the user is
1197 prohibited from editing it, which is mainly useful as a component of one
1198 of the composite widgets.
1200 The syntax for the @code{const} widget is:
1203 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1206 The @var{value}, if present, is used to initialize the @code{:value}
1207 property and can be any s-expression.
1210 This will display any valid s-expression in an immutable part of the
1214 There are two variations of the @code{const} widget, namely
1215 @code{variable-item} and @code{function-item}. These should contain a
1216 symbol with a variable or function binding. The major difference from
1217 the @code{const} widget is that they will allow the user to see the
1218 variable or function documentation for the symbol.
1220 @deffn Widget variable-item
1221 An immutable symbol that is bound as a variable.
1224 @deffn Widget function-item
1225 An immutable symbol that is bound as a function.
1228 @node generic, atoms, constants, Sexp Types
1229 @comment node-name, next, previous, up
1230 @subsection Generic Sexp Widget
1231 @cindex generic sexp widget
1233 The @code{sexp} widget can contain any Lisp expression, and allows the
1234 user to edit it inline in the buffer.
1236 The syntax for the @code{sexp} widget is:
1239 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1243 This will allow you to edit any valid s-expression in an editable buffer
1246 The @code{sexp} widget takes the same keyword arguments as the
1247 @code{editable-field} widget. @xref{editable-field}.
1250 @node atoms, composite, generic, Sexp Types
1251 @comment node-name, next, previous, up
1252 @subsection Atomic Sexp Widgets
1253 @cindex atomic sexp widget
1255 The atoms are s-expressions that do not consist of other s-expressions.
1256 For example, a string, a file name, or a symbol are atoms, while a list
1257 is a composite type. You can edit the value of an atom with the
1260 The syntax for all the atoms are:
1263 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1266 The @var{value}, if present, is used to initialize the @code{:value}
1267 property and must be an expression of the same type as the widget.
1268 That is, the string widget can only be initialized with a string.
1270 All the atom widgets take the same keyword arguments as the
1271 @code{editable-field} widget. @xref{editable-field}.
1273 @deffn Widget string
1274 Allows you to edit a string in an editable field.
1277 @deffn Widget regexp
1278 Allows you to edit a regular expression in an editable field.
1281 @deffn Widget character
1282 Allows you to enter a character in an editable field.
1286 Allows you to edit a file name in an editable field.
1290 @vindex must-match@r{ keyword}
1292 If this is set to non-@code{nil}, only existing file names will be
1293 allowed in the minibuffer.
1297 @deffn Widget directory
1298 Allows you to edit a directory name in an editable field.
1299 Similar to the @code{file} widget.
1302 @deffn Widget symbol
1303 Allows you to edit a Lisp symbol in an editable field.
1306 @deffn Widget function
1307 Allows you to edit a lambda expression, or a function name with completion.
1310 @deffn Widget variable
1311 Allows you to edit a variable name, with completion.
1314 @deffn Widget integer
1315 Allows you to edit an integer in an editable field.
1318 @deffn Widget number
1319 Allows you to edit a number in an editable field.
1322 @deffn Widget boolean
1323 Allows you to edit a boolean. In Lisp this means a variable which is
1324 either @code{nil} meaning false, or non-@code{nil} meaning true.
1328 @node composite, , atoms, Sexp Types
1329 @comment node-name, next, previous, up
1330 @subsection Composite Sexp Widgets
1331 @cindex composite sexp widgets
1333 The syntax for the composite widget is:
1336 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1340 where each @var{component} must be a widget type. Each component widget
1341 will be displayed in the buffer, and will be editable by the user.
1344 The value of a @code{cons} widget is a cons-cell where the @sc{car} is
1345 the value of the first component and the @sc{cdr} is the value of the
1346 second component. There must be exactly two components.
1350 The value of a @code{list} widget is a list containing the value of
1351 each of its component.
1354 @deffn Widget vector
1355 The value of a @code{vector} widget is a vector containing the value of
1356 each of its component.
1359 The above suffice for specifying fixed size lists and vectors. To get
1360 variable length lists and vectors, you can use a @code{choice},
1361 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1362 keywords. If any component of a composite widget has the @code{:inline}
1363 keyword set, its value must be a list which will then be spliced into
1364 the composite. For example, to specify a list whose first element must
1365 be a file name, and whose remaining arguments should either by the
1366 symbol @code{t} or two files, you can use the following widget
1373 :value ("foo" "bar")
1377 The value of a widget of this type will either have the form
1378 @code{(file t)} or @code{(file string string)}.
1380 This concept of inline is probably hard to understand. It was certainly
1381 hard to implement, so instead of confusing you more by trying to explain
1382 it here, I'll just suggest you meditate over it for a while.
1384 @deffn Widget choice
1385 Allows you to edit a sexp which may have one of a fixed set of types.
1386 It is currently implemented with the @code{choice-menu} basic widget,
1387 and has a similar syntax.
1391 Allows you to specify a type which must be a list whose elements all
1392 belong to given set. The elements of the list are not significant.
1393 This is implemented on top of the @code{checklist} basic widget, and has
1397 @deffn Widget repeat
1398 Allows you to specify a variable length list whose members are all of
1399 the same type. Implemented on top of the @code{editable-list} basic
1400 widget, and has a similar syntax.
1403 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1404 @comment node-name, next, previous, up
1406 @cindex properties of widgets
1407 @cindex widget properties
1409 You can examine or set the value of a widget by using the widget object
1410 that was returned by @code{widget-create}.
1412 @defun widget-value widget
1413 Return the current value contained in @var{widget}.
1414 It is an error to call this function on an uninitialized widget.
1417 @defun widget-value-set widget value
1418 Set the value contained in @var{widget} to @var{value}.
1419 It is an error to call this function with an invalid @var{value}.
1422 @strong{Important:} You @emph{must} call @code{widget-setup} after
1423 modifying the value of a widget before the user is allowed to edit the
1424 widget again. It is enough to call @code{widget-setup} once if you
1425 modify multiple widgets. This is currently only necessary if the widget
1426 contains an editing field, but may be necessary for other widgets in the
1429 If your application needs to associate some information with the widget
1430 objects, for example a reference to the item being edited, it can be
1431 done with @code{widget-put} and @code{widget-get}. The property names
1432 must begin with a @samp{:}.
1434 @defun widget-put widget property value
1435 In @var{widget} set @var{property} to @var{value}.
1436 @var{property} should be a symbol, while @var{value} can be anything.
1439 @defun widget-get widget property
1440 In @var{widget} return the value for @var{property}.
1441 @var{property} should be a symbol, the value is what was last set by
1442 @code{widget-put} for @var{property}.
1445 @defun widget-member widget property
1446 Non-@code{nil} if @var{widget} has a value (even @code{nil}) for
1447 property @var{property}.
1450 Occasionally it can be useful to know which kind of widget you have,
1451 i.e.@: the name of the widget type you gave when the widget was created.
1453 @defun widget-type widget
1454 Return the name of @var{widget}, a symbol.
1457 @cindex active widget
1458 @cindex inactive widget
1459 @cindex activate a widget
1460 @cindex deactivate a widget
1461 Widgets can be in two states: active, which means they are modifiable by
1462 the user, or inactive, which means they cannot be modified by the user.
1463 You can query or set the state with the following code:
1466 ;; Examine if @var{widget} is active or not.
1467 (if (widget-apply @var{widget} :active)
1468 (message "Widget is active.")
1469 (message "Widget is inactive.")
1471 ;; Make @var{widget} inactive.
1472 (widget-apply @var{widget} :deactivate)
1474 ;; Make @var{widget} active.
1475 (widget-apply @var{widget} :activate)
1478 A widget is inactive if it, or any of its ancestors (found by
1479 following the @code{:parent} link), have been deactivated. To make sure
1480 a widget is really active, you must therefore activate both it and
1485 (widget-apply widget :activate)
1486 (setq widget (widget-get widget :parent)))
1489 You can check if a widget has been made inactive by examining the value
1490 of the @code{:inactive} keyword. If this is non-@code{nil}, the widget itself
1491 has been deactivated. This is different from using the @code{:active}
1492 keyword, in that the latter tells you if the widget @strong{or} any of
1493 its ancestors have been deactivated. Do not attempt to set the
1494 @code{:inactive} keyword directly. Use the @code{:activate}
1495 @code{:deactivate} keywords instead.
1498 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1499 @comment node-name, next, previous, up
1500 @section Defining New Widgets
1502 @cindex defining new widgets
1504 You can define specialized widgets with @code{define-widget}. It allows
1505 you to create a shorthand for more complex widgets, including specifying
1506 component widgets and new default values for the keyword
1509 @defun define-widget name class doc &rest args
1510 Define a new widget type named @var{name} from @code{class}.
1512 @var{name} and class should both be symbols, @code{class} should be one
1513 of the existing widget types.
1515 The third argument @var{doc} is a documentation string for the widget.
1517 After the new widget has been defined, the following two calls will
1518 create identical widgets:
1523 (widget-create @var{name})
1528 (apply widget-create @var{class} @var{args})
1534 Using @code{define-widget} just stores the definition of the widget type
1535 in the @code{widget-type} property of @var{name}, which is what
1536 @code{widget-create} uses.
1538 If you only want to specify defaults for keywords with no complex
1539 conversions, you can use @code{identity} as your conversion function.
1541 The following additional keyword arguments are useful when defining new
1544 @vindex convert-widget@r{ keyword}
1545 @item :convert-widget
1546 Function to convert a widget type before creating a widget of that
1547 type. It takes a widget type as an argument, and returns the converted
1548 widget type. When a widget is created, this function is called for the
1549 widget type and all the widget's parent types, most derived first.
1551 The following predefined functions can be used here:
1553 @defun widget-types-convert-widget widget
1554 Convert @code{:args} as widget types in @var{widget}.
1557 @defun widget-value-convert-widget widget
1558 Initialize @code{:value} from @code{:args} in @var{widget}.
1561 @vindex copy@r{ keyword}
1563 Function to deep copy a widget type. It takes a shallow copy of the
1564 widget type as an argument (made by @code{copy-sequence}), and returns a
1565 deep copy. The purpose of this is to avoid having different instances
1566 of combined widgets share nested attributes.
1568 The following predefined functions can be used here:
1570 @defun widget-types-copy widget
1571 Copy @code{:args} as widget types in @var{widget}.
1574 @vindex value-to-internal@r{ keyword}
1575 @item :value-to-internal
1576 Function to convert the value to the internal format. The function
1577 takes two arguments, a widget and an external value, and returns the
1578 internal value. The function is called on the present @code{:value}
1579 when the widget is created, and on any value set later with
1580 @code{widget-value-set}.
1582 @vindex value-to-external@r{ keyword}
1583 @item :value-to-external
1584 Function to convert the value to the external format. The function
1585 takes two arguments, a widget and an internal value, and returns the
1586 external value. The function is called on the present @code{:value}
1587 when the widget is created, and on any value set later with
1588 @code{widget-value-set}.
1590 @vindex create@r{ keyword}
1592 Function to create a widget from scratch. The function takes one
1593 argument, a widget type, and creates a widget of that type, inserts it
1594 in the buffer, and returns a widget object.
1596 @vindex delete@r{ keyword}
1598 Function to delete a widget. The function takes one argument, a widget,
1599 and should remove all traces of the widget from the buffer.
1601 The default value is:
1603 @defun widget-default-delete widget
1604 Remove @var{widget} from the buffer.
1605 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1608 In most cases you should not change this value, but instead use
1609 @code{:value-delete} to make any additional cleanup.
1611 @vindex value-create@r{ keyword}
1613 Function to expand the @samp{%v} escape in the format string. It will
1614 be called with the widget as its argument and should insert a
1615 representation of the widget's value in the buffer.
1617 Nested widgets should be listed in @code{:children} or @code{:buttons}
1618 to make sure they are automatically deleted.
1620 @vindex value-delete@r{ keyword}
1622 Should remove the representation of the widget's value from the buffer.
1623 It will be called with the widget as its argument. It doesn't have to
1624 remove the text, but it should release markers and delete nested widgets
1625 if these are not listed in @code{:children} or @code{:buttons}.
1627 @vindex value-get@r{ keyword}
1629 Function to extract the value of a widget, as it is displayed in the
1632 The following predefined function can be used here:
1634 @defun widget-value-value-get widget
1635 Return the @code{:value} property of @var{widget}.
1638 @vindex format-handler@r{ keyword}
1639 @item :format-handler
1640 Function to handle unknown @samp{%} escapes in the format string. It
1641 will be called with the widget and the character that follows the
1642 @samp{%} as arguments. You can set this to allow your widget to handle
1643 non-standard escapes.
1645 @findex widget-default-format-handler
1646 You should end up calling @code{widget-default-format-handler} to handle
1647 unknown escape sequences, which will handle the @samp{%h} and any future
1648 escape sequences, as well as give an error for unknown escapes.
1650 @vindex action@r{ keyword}
1652 Function to handle user initiated events. By default, @code{:notify}
1655 The following predefined function can be used here:
1657 @defun widget-parent-action widget &optional event
1658 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1659 Optional @var{event} is the event that triggered the action.
1662 @vindex prompt-value@r{ keyword}
1664 Function to prompt for a value in the minibuffer. The function should
1665 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1666 @var{unbound} and should return a value for widget entered by the user.
1667 @var{prompt} is the prompt to use. @var{value} is the default value to
1668 use, unless @var{unbound} is non-@code{nil}, in which case there is no default
1669 value. The function should read the value using the method most natural
1670 for this widget, and does not have to check that it matches.
1673 If you want to define a new widget from scratch, use the @code{default}
1676 @deffn Widget default
1677 Widget used as a base for other widgets.
1679 It provides most of the functionality that is referred to as ``by
1680 default'' in this text.
1683 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1684 @comment node-name, next, previous, up
1685 @section Widget Browser
1686 @cindex widget browser
1688 There is a separate package to browse widgets. This is intended to help
1689 programmers who want to examine the content of a widget. The browser
1690 shows the value of each keyword, but uses links for certain keywords
1691 such as @samp{:parent}, which avoids printing cyclic structures.
1693 @deffn Command widget-browse @var{widget}
1694 Create a widget browser for @var{widget}.
1695 When called interactively, prompt for @var{widget}.
1698 @deffn Command widget-browse-other-window @var{widget}
1699 Create a widget browser for @var{widget} and show it in another window.
1700 When called interactively, prompt for @var{widget}.
1703 @deffn Command widget-browse-at @var{pos}
1704 Create a widget browser for the widget at @var{pos}.
1705 When called interactively, use the position of point.
1708 @node Widget Minor Mode, Utilities, Widget Browser, Top
1709 @comment node-name, next, previous, up
1710 @section Widget Minor Mode
1711 @cindex widget minor mode
1713 There is a minor mode for manipulating widgets in major modes that
1714 don't provide any support for widgets themselves. This is mostly
1715 intended to be useful for programmers doing experiments.
1717 @deffn Command widget-minor-mode
1718 Toggle minor mode for traversing widgets.
1719 With arg, turn widget mode on if and only if arg is positive.
1722 @defvar widget-minor-mode-keymap
1723 Keymap used in @code{widget-minor-mode}.
1726 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1727 @comment node-name, next, previous, up
1729 @cindex utility functions for widgets
1731 @defun widget-prompt-value widget prompt [ value unbound ]
1732 Prompt for a value matching @var{widget}, using @var{prompt}.
1733 The current value is assumed to be @var{value}, unless @var{unbound} is
1734 non-@code{nil}.@refill
1737 @defun widget-get-sibling widget
1738 Get the item which @var{widget} is assumed to toggle.
1739 This is only meaningful for radio buttons or checkboxes in a list.
1742 @node Widget Wishlist, Index, Utilities, Top
1743 @comment node-name, next, previous, up
1749 It should be possible to add or remove items from a list with @kbd{C-k}
1750 and @kbd{C-o} (suggested by @sc{rms}).
1753 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1754 dash (@samp{-}). The dash should be a button that, when invoked, asks
1755 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1756 the ugly buttons, the dash is my idea).
1759 The @code{menu-choice} tag should be prettier, something like the abbreviated
1763 Finish @code{:tab-order}.
1766 Make indentation work with glyphs and proportional fonts.
1769 Add commands to show overview of object and class hierarchies to the
1773 Find a way to disable mouse highlight for inactive widgets.
1776 Find a way to make glyphs look inactive.
1779 Add @code{property-list} widget.
1782 Add @code{association-list} widget.
1785 Add @code{key-binding} widget.
1788 Add @code{widget} widget for editing widget specifications.
1791 Find clean way to implement variable length list.
1792 See @code{TeX-printer-list} for an explanation.
1795 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1798 Add a @code{mailto} widget.
1801 @node Index, , Widget Wishlist, Top
1802 @comment node-name, next, previous, up
1805 This is an alphabetical listing of all concepts, functions, commands,
1806 variables, and widgets described in this manual.
1809 @setchapternewpage odd
1814 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0