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 does 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.
319 @deffn Command widget-backward &optional count
320 Move point @var{count} buttons or editing fields backward.
324 @node Programming Example, Setting Up the Buffer, User Interface, Top
325 @comment node-name, next, previous, up
326 @section Programming Example
328 @cindex widgets, programming example
329 @cindex example of using widgets
330 Here is the code to implement the user interface example (@pxref{User
339 (defvar widget-example-repeat)
341 (defun widget-example ()
342 "Create the widgets from the Widget manual."
344 (switch-to-buffer "*Widget Example*")
345 (kill-all-local-variables)
346 (make-local-variable 'widget-example-repeat)
347 (let ((inhibit-read-only t))
350 (widget-insert "Here is some documentation.\n\nName: ")
351 (widget-create 'editable-field
353 :format "%v " ; Text after the field!
355 (widget-create 'menu-choice
358 :help-echo "Choose me, please!"
359 :notify (lambda (widget &rest ignore)
360 (message "%s is a good choice!"
361 (widget-value widget)))
362 '(item :tag "This option" :value "This")
363 '(choice-item "That option")
364 '(editable-field :menu-tag "No option" "Thus option"))
365 (widget-insert "Address: ")
366 (widget-create 'editable-field
367 "Some Place\nIn some City\nSome country.")
368 (widget-insert "\nSee also ")
370 :notify (lambda (&rest ignore)
371 (widget-value-set widget-example-repeat
376 " for more information.\n\nNumbers: count to three below\n")
377 (setq widget-example-repeat
378 (widget-create 'editable-list
379 :entry-format "%i %d %v"
380 :notify (lambda (widget &rest ignore)
381 (let ((old (widget-get widget
383 (new (length (widget-value widget))))
385 (widget-put widget ':example-length new)
386 (message "You can count to %d." new))))
387 :value '("One" "Eh, two?" "Five!")
388 '(editable-field :value "three")))
389 (widget-insert "\n\nSelect multiple:\n\n")
390 (widget-create 'checkbox t)
391 (widget-insert " This\n")
392 (widget-create 'checkbox nil)
393 (widget-insert " That\n")
394 (widget-create 'checkbox
395 :notify (lambda (&rest ignore) (message "Tickle"))
397 (widget-insert " Thus\n\nSelect one:\n\n")
398 (widget-create 'radio-button-choice
400 :notify (lambda (widget &rest ignore)
401 (message "You selected %s"
402 (widget-value widget)))
403 '(item "One") '(item "Another One.") '(item "A Final One."))
405 (widget-create 'push-button
406 :notify (lambda (&rest ignore)
407 (if (= (length (widget-value widget-example-repeat))
409 (message "Congratulation!")
410 (error "Three was the count!")))
413 (widget-create 'push-button
414 :notify (lambda (&rest ignore)
418 (use-local-map widget-keymap)
422 @node Setting Up the Buffer, Basic Types, Programming Example, Top
423 @comment node-name, next, previous, up
424 @section Setting Up the Buffer
426 Widgets are created with @code{widget-create}, which returns a
427 @dfn{widget} object. This object can be queried and manipulated by
428 other widget functions, until it is deleted with @code{widget-delete}.
429 After the widgets have been created, @code{widget-setup} must be called
432 @defun widget-create type [ keyword argument ]@dots{}
433 Create and return a widget of type @var{type}.
434 The syntax for the @var{type} argument is described in @ref{Basic Types}.
436 The keyword arguments can be used to overwrite the keyword arguments
437 that are part of @var{type}.
440 @defun widget-delete widget
441 Delete @var{widget} and remove it from the buffer.
445 Set up a buffer to support widgets.
447 This should be called after creating all the widgets and before allowing
448 the user to edit them.
452 If you want to insert text outside the widgets in the form, the
453 recommended way to do that is with @code{widget-insert}.
456 Insert the arguments, either strings or characters, at point.
457 The inserted text will be read-only.
460 There is a standard widget keymap which you might find useful.
462 @findex widget-button-press
463 @findex widget-button-click
464 @defvr Const widget-keymap
465 A keymap with the global keymap as its parent.@*
466 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
467 @code{widget-backward}, respectively. @key{RET} and @kbd{Mouse-2}
468 are bound to @code{widget-button-press} and
469 @code{widget-button-click}.@refill
472 @defvar widget-global-map
473 Keymap used by @code{widget-button-press} and @code{widget-button-click}
474 when not on a button. By default this is @code{global-map}.
477 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
478 @comment node-name, next, previous, up
481 The syntax of a type specification is given below:
484 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
488 Where, @var{name} is a widget name, @var{keyword} is the name of a
489 property, @var{argument} is the value of the property, and @var{args}
490 are interpreted in a widget specific way.
492 @cindex keyword arguments
493 The following keyword arguments that apply to all widgets:
496 @vindex value@r{ keyword}
498 The initial value for widgets of this type.
500 @vindex format@r{ keyword}
502 This string will be inserted in the buffer when you create a widget.
503 The following @samp{%} escapes are available:
508 The text inside will be marked as a button.
510 By default, the text will be shown in @code{widget-button-face}, and
511 surrounded by brackets.
513 @defopt widget-button-prefix
514 String to prefix buttons.
517 @defopt widget-button-suffix
518 String to suffix buttons.
523 The text inside will be displayed with the face specified by
527 This will be replaced with the buffer representation of the widget's
528 value. What this is depends on the widget type.
531 Insert the string specified by @code{:doc} here.
534 Like @samp{%d}, with the following modifications: If the documentation
535 string is more than one line, it will add a button which will toggle
536 between showing only the first line, and showing the full text.
537 Furthermore, if there is no @code{:doc} property in the widget, it will
538 instead examine the @code{:documentation-property} property. If it is a
539 lambda expression, it will be called with the widget's value as an
540 argument, and the result will be used as the documentation text.
543 Insert the string specified by @code{:tag} here, or the @code{princ}
544 representation of the value if there is no tag.
547 Insert a literal @samp{%}.
550 @vindex button-face@r{ keyword}
552 Face used to highlight text inside %[ %] in the format.
554 @vindex button-prefix@r{ keyword}
555 @vindex button-suffix@r{ keyword}
557 @itemx :button-suffix
558 Text around %[ %] in the format.
566 The string is inserted literally.
569 The value of the symbol is expanded according to this table.
572 @vindex doc@r{ keyword}
574 The string inserted by the @samp{%d} escape in the format
577 @vindex tag@r{ keyword}
579 The string inserted by the @samp{%t} escape in the format
582 @vindex tag-glyph@r{ keyword}
584 Name of image to use instead of the string specified by @code{:tag} on
585 Emacsen that supports it.
587 @vindex help-echo@r{ keyword}
589 Specifies how to display a message whenever you move to the widget with
590 either @code{widget-forward} or @code{widget-backward} or move the mouse
591 over it (using the standard @code{help-echo} mechanism). The argument
592 is either a string to display, a function of one argument, the widget,
593 which should return a string to display, or a form that evaluates to
596 @vindex follow-link@r{ keyword}
598 Specifies how to interpret a @key{mouse-1} click on the widget.
599 @xref{Links and Mouse-1,,, elisp, the Emacs Lisp Reference Manual}.
601 @vindex indent@r{ keyword}
603 An integer indicating the absolute number of spaces to indent children
606 @vindex offset@r{ keyword}
608 An integer indicating how many extra spaces to add to the widget's
609 grandchildren compared to this widget.
611 @vindex extra-offset@r{ keyword}
613 An integer indicating how many extra spaces to add to the widget's
614 children compared to this widget.
616 @vindex notify@r{ keyword}
618 A function called each time the widget or a nested widget is changed.
619 The function is called with two or three arguments. The first argument
620 is the widget itself, the second argument is the widget that was
621 changed, and the third argument is the event leading to the change, if
624 @vindex menu-tag@r{ keyword}
626 Tag used in the menu when the widget is used as an option in a
627 @code{menu-choice} widget.
629 @vindex menu-tag-get@r{ keyword}
631 Function used for finding the tag when the widget is used as an option
632 in a @code{menu-choice} widget. By default, the tag used will be either the
633 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
634 representation of the @code{:value} property if not.
636 @vindex match@r{ keyword}
638 Should be a function called with two arguments, the widget and a value,
639 and returning non-@code{nil} if the widget can represent the specified value.
641 @vindex validate@r{ keyword}
643 A function which takes a widget as an argument, and returns @code{nil}
644 if the widget's current value is valid for the widget. Otherwise it
645 should return the widget containing the invalid data, and set that
646 widget's @code{:error} property to a string explaining the error.
648 The following predefined function can be used:
650 @defun widget-children-validate widget
651 All the @code{:children} of @var{widget} must be valid.
654 @vindex tab-order@r{ keyword}
656 Specify the order in which widgets are traversed with
657 @code{widget-forward} or @code{widget-backward}. This is only partially
662 Widgets with tabbing order @code{-1} are ignored.
665 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
666 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
667 whichever comes first.
670 When on a widget with no tabbing order specified, go to the next widget
671 in the buffer with a positive tabbing order, or @code{nil}
674 @vindex parent@r{ keyword}
676 The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
677 element of a @code{editable-list} widget).
679 @vindex sibling-args@r{ keyword}
681 This keyword is only used for members of a @code{radio-button-choice} or
682 @code{checklist}. The value should be a list of extra keyword
683 arguments, which will be used when creating the @code{radio-button} or
684 @code{checkbox} associated with this item.
688 @deffn {User Option} widget-glyph-directory
689 Directory where glyphs are found.
690 Widget will look here for a file with the same name as specified for the
691 image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
694 @deffn{User Option} widget-glyph-enable
695 If non-@code{nil}, allow glyphs to appear on displays where they are supported.
707 * radio-button-choice::
717 @node link, url-link, Basic Types, Basic Types
718 @comment node-name, next, previous, up
719 @subsection The @code{link} Widget
720 @findex link@r{ widget}
725 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
728 The @var{value}, if present, is used to initialize the @code{:value}
729 property. The value should be a string, which will be inserted in the
732 By default the link will be shown in brackets.
734 @defopt widget-link-prefix
735 String to prefix links.
738 @defopt widget-link-suffix
739 String to suffix links.
742 @node url-link, info-link, link, Basic Types
743 @comment node-name, next, previous, up
744 @subsection The @code{url-link} Widget
745 @findex url-link@r{ widget}
750 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
753 @findex browse-url-browser-function@r{, and @code{url-link} widget}
754 When this link is invoked, the @acronym{WWW} browser specified by
755 @code{browse-url-browser-function} will be called with @var{url}.
757 @node info-link, push-button, url-link, Basic Types
758 @comment node-name, next, previous, up
759 @subsection The @code{info-link} Widget
760 @findex info-link@r{ widget}
765 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
768 When this link is invoked, the built-in Info reader is started on
771 @node push-button, editable-field, info-link, Basic Types
772 @comment node-name, next, previous, up
773 @subsection The @code{push-button} Widget
774 @findex push-button@r{ widget}
779 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
782 The @var{value}, if present, is used to initialize the @code{:value}
783 property. The value should be a string, which will be inserted in the
786 By default the tag will be shown in brackets.
788 @defopt widget-push-button-prefix
789 String to prefix push buttons.
792 @defopt widget-push-button-suffix
793 String to suffix push buttons.
796 @node editable-field, text, push-button, Basic Types
797 @comment node-name, next, previous, up
798 @subsection The @code{editable-field} Widget
799 @findex editable-field@r{ widget}
804 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
807 The @var{value}, if present, is used to initialize the @code{:value}
808 property. The value should be a string, which will be inserted in
809 field. This widget will match all string values.
811 The following extra properties are recognized:
814 @vindex size@r{ keyword}
816 The width of the editable field.@*
817 By default the field will reach to the end of the line.
819 @vindex value-face@r{ keyword}
821 Face used for highlighting the editable field. Default is
822 @code{widget-field-face}, see @ref{User Interface}.
824 @vindex secret@r{ keyword}
826 Character used to display the value. You can set this to e.g.@: @code{?*}
827 if the field contains a password or other secret information. By
828 default, this is @code{nil}, and the value is not secret.
830 @vindex valid-regexp@r{ keyword}
832 By default the @code{:validate} function will match the content of the
833 field with the value of this attribute. The default value is @code{""}
834 which matches everything.
836 @vindex keymap@r{ keyword}
837 @vindex widget-field-keymap
839 Keymap used in the editable field. The default value is
840 @code{widget-field-keymap}, which allows you to use all the normal
841 editing commands, even if the buffer's major mode suppresses some of
842 them. Pressing @key{RET} invokes the function specified by
846 @node text, menu-choice, editable-field, Basic Types
847 @comment node-name, next, previous, up
848 @subsection The @code{text} Widget
849 @findex text@r{ widget}
851 @vindex widget-text-keymap
852 This is just like @code{editable-field}, but intended for multiline text
853 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
854 does not rebind the @key{RET} key.
856 @node menu-choice, radio-button-choice, text, Basic Types
857 @comment node-name, next, previous, up
858 @subsection The @code{menu-choice} Widget
859 @findex menu-choice@r{ widget}
864 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
867 The @var{type} argument represents each possible choice. The widget's
868 value will be that of the chosen @var{type} argument. This widget will
869 match any value matching at least one of the specified @var{type}
873 @vindex void@r{ keyword}
875 Widget type used as a fallback when the value does not match any of the
876 specified @var{type} arguments.
878 @vindex case-fold@r{ keyword}
880 Set this to @code{nil} if you don't want to ignore case when prompting for a
881 choice through the minibuffer.
883 @vindex children@r{ keyword}
885 A list whose @sc{car} is the widget representing the currently chosen
888 @vindex choice@r{ keyword}
890 The current chosen type.
892 @vindex args@r{ keyword}
897 @node radio-button-choice, item, menu-choice, Basic Types
898 @comment node-name, next, previous, up
899 @subsection The @code{radio-button-choice} Widget
900 @findex radio-button-choice@r{ widget}
905 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
908 The @var{type} argument represents each possible choice. The widget's
909 value will be that of the chosen @var{type} argument. This widget will
910 match any value matching at least one of the specified @var{type}
913 The following extra properties are recognized.
916 @vindex entry-format@r{ keyword}
918 This string will be inserted for each entry in the list.
919 The following @samp{%} escapes are available:
922 Replace with the buffer representation of the @var{type} widget.
924 Replace with the radio button.
926 Insert a literal @samp{%}.
929 @vindex button-args@r{ keyword}
931 A list of keywords to pass to the radio buttons. Useful for setting
932 e.g.@: the @samp{:help-echo} for each button.
934 @vindex buttons@r{ keyword}
936 The widgets representing the radio buttons.
938 @vindex children@r{ keyword}
940 The widgets representing each type.
942 @vindex choice@r{ keyword}
944 The current chosen type
946 @vindex args@r{ keyword}
951 You can add extra radio button items to a @code{radio-button-choice}
952 widget after it has been created with the function
953 @code{widget-radio-add-item}.
955 @defun widget-radio-add-item widget type
956 Add to @code{radio-button-choice} widget @var{widget} a new radio button
957 item of type @var{type}.
960 Please note that such items added after the @code{radio-button-choice}
961 widget has been created will @strong{not} be properly destructed when
962 you call @code{widget-delete}.
964 @node item, choice-item, radio-button-choice, Basic Types
965 @comment node-name, next, previous, up
966 @subsection The @code{item} Widget
967 @findex item@r{ widget}
972 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
975 The @var{value}, if present, is used to initialize the @code{:value}
976 property. The value should be a string, which will be inserted in the
977 buffer. This widget will only match the specified value.
979 @node choice-item, toggle, item, Basic Types
980 @comment node-name, next, previous, up
981 @subsection The @code{choice-item} Widget
982 @findex choice-item@r{ widget}
987 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
990 The @var{value}, if present, is used to initialize the @code{:value}
991 property. The value should be a string, which will be inserted in the
992 buffer as a button. Activating the button of a @code{choice-item} is
993 equivalent to activating the parent widget. This widget will only match
996 @node toggle, checkbox, choice-item, Basic Types
997 @comment node-name, next, previous, up
998 @subsection The @code{toggle} Widget
999 @findex toggle@r{ widget}
1004 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
1007 The widget has two possible states, @samp{on} and @samp{off}, which
1008 correspond to a @code{t} or @code{nil} value, respectively.
1010 The following extra properties are recognized:
1014 A string representing the @samp{on} state. By default the string
1017 A string representing the @samp{off} state. By default the string
1019 @vindex on-glyph@r{ keyword}
1021 Name of a glyph to be used instead of the @samp{:on} text string, on
1022 emacsen that supports this.
1023 @vindex off-glyph@r{ keyword}
1025 Name of a glyph to be used instead of the @samp{:off} text string, on
1026 emacsen that supports this.
1029 @node checkbox, checklist, toggle, Basic Types
1030 @comment node-name, next, previous, up
1031 @subsection The @code{checkbox} Widget
1032 @findex checkbox@r{ widget}
1034 This widget has two possible states, @samp{selected} and
1035 @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
1040 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
1043 @node checklist, editable-list, checkbox, Basic Types
1044 @comment node-name, next, previous, up
1045 @subsection The @code{checklist} Widget
1046 @findex checklist@r{ widget}
1051 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
1054 The @var{type} arguments represent each checklist item. The widget's
1055 value will be a list containing the values of all checked @var{type}
1056 arguments. The checklist widget will match a list whose elements all
1057 match at least one of the specified @var{type} arguments.
1059 The following extra properties are recognized:
1062 @vindex entry-format@r{ keyword}
1064 This string will be inserted for each entry in the list.
1065 The following @samp{%} escapes are available:
1068 Replaced with the buffer representation of the @var{type} widget.
1070 Replace with the checkbox.
1072 Insert a literal @samp{%}.
1075 @vindex greedy@r{ keyword}
1077 Usually a checklist will only match if the items are in the exact
1078 sequence given in the specification. By setting @code{:greedy} to
1079 non-@code{nil}, it will allow the items to come in any sequence.
1080 However, if you extract the value they will be in the sequence given
1081 in the checklist, i.e.@: the original sequence is forgotten.
1083 @vindex button-args@r{ keyword}
1085 A list of keywords to pass to the checkboxes. Useful for setting
1086 e.g.@: the @samp{:help-echo} for each checkbox.
1088 @vindex buttons@r{ keyword}
1090 The widgets representing the checkboxes.
1092 @vindex children@r{ keyword}
1094 The widgets representing each type.
1096 @vindex args@r{ keyword}
1101 @node editable-list, group, checklist, Basic Types
1102 @comment node-name, next, previous, up
1103 @subsection The @code{editable-list} Widget
1104 @findex editable-list@r{ widget}
1109 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
1112 The value is a list, where each member represents one widget of type
1115 The following extra properties are recognized:
1118 @vindex entry-format@r{ keyword}
1120 This string will be inserted for each entry in the list.
1121 The following @samp{%} escapes are available:
1124 This will be replaced with the buffer representation of the @var{type}
1127 Insert the @b{[INS]} button.
1129 Insert the @b{[DEL]} button.
1131 Insert a literal @samp{%}.
1134 @vindex insert-button-args@r{ keyword}
1135 @item :insert-button-args
1136 A list of keyword arguments to pass to the insert buttons.
1138 @vindex delete-button-args@r{ keyword}
1139 @item :delete-button-args
1140 A list of keyword arguments to pass to the delete buttons.
1142 @vindex append-button-args@r{ keyword}
1143 @item :append-button-args
1144 A list of keyword arguments to pass to the trailing insert button.
1146 @vindex buttons@r{ keyword}
1148 The widgets representing the insert and delete buttons.
1150 @vindex children@r{ keyword}
1152 The widgets representing the elements of the list.
1154 @vindex args@r{ keyword}
1156 List whose @sc{car} is the type of the list elements.
1159 @node group, , editable-list, Basic Types
1160 @comment node-name, next, previous, up
1161 @subsection The @code{group} Widget
1162 @findex group@r{ widget}
1164 This widget simply group other widgets together.
1169 TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
1172 The value is a list, with one member for each @var{type}.
1174 @node Sexp Types, Widget Properties, Basic Types, Top
1179 A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
1180 for short, are also available. These basically fall in several
1181 categories described in this section.
1190 @node constants, generic, Sexp Types, Sexp Types
1191 @comment node-name, next, previous, up
1192 @subsection The Constant Widgets
1193 @cindex constant widgets
1195 The @code{const} widget can contain any Lisp expression, but the user is
1196 prohibited from editing it, which is mainly useful as a component of one
1197 of the composite widgets.
1199 The syntax for the @code{const} widget is:
1202 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1205 The @var{value}, if present, is used to initialize the @code{:value}
1206 property and can be any s-expression.
1209 This will display any valid s-expression in an immutable part of the
1213 There are two variations of the @code{const} widget, namely
1214 @code{variable-item} and @code{function-item}. These should contain a
1215 symbol with a variable or function binding. The major difference from
1216 the @code{const} widget is that they will allow the user to see the
1217 variable or function documentation for the symbol.
1219 @deffn Widget variable-item
1220 An immutable symbol that is bound as a variable.
1223 @deffn Widget function-item
1224 An immutable symbol that is bound as a function.
1227 @node generic, atoms, constants, Sexp Types
1228 @comment node-name, next, previous, up
1229 @subsection Generic Sexp Widget
1230 @cindex generic sexp widget
1232 The @code{sexp} widget can contain any Lisp expression, and allows the
1233 user to edit it inline in the buffer.
1235 The syntax for the @code{sexp} widget is:
1238 TYPE ::= (sexp [KEYWORD ARGUMENT]... [ VALUE ])
1242 This will allow you to edit any valid s-expression in an editable buffer
1245 The @code{sexp} widget takes the same keyword arguments as the
1246 @code{editable-field} widget. @xref{editable-field}.
1249 @node atoms, composite, generic, Sexp Types
1250 @comment node-name, next, previous, up
1251 @subsection Atomic Sexp Widgets
1252 @cindex atomic sexp widget
1254 The atoms are s-expressions that do not consist of other s-expressions.
1255 For example, a string, a file name, or a symbol are atoms, while a list
1256 is a composite type. You can edit the value of an atom with the
1259 The syntax for all the atoms are:
1262 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1265 The @var{value}, if present, is used to initialize the @code{:value}
1266 property and must be an expression of the same type as the widget.
1267 That is, the string widget can only be initialized with a string.
1269 All the atom widgets take the same keyword arguments as the
1270 @code{editable-field} widget. @xref{editable-field}.
1272 @deffn Widget string
1273 Allows you to edit a string in an editable field.
1276 @deffn Widget regexp
1277 Allows you to edit a regular expression in an editable field.
1280 @deffn Widget character
1281 Allows you to enter a character in an editable field.
1285 Allows you to edit a file name in an editable field. If you invoke
1286 the tag button, you can edit the file name in the mini-buffer with
1291 @vindex must-match@r{ keyword}
1293 If this is set to non-@code{nil}, only existing file names will be
1294 allowed in the minibuffer.
1298 @deffn Widget directory
1299 Allows you to edit a directory name in an editable field.
1300 Similar to the @code{file} widget.
1303 @deffn Widget symbol
1304 Allows you to edit a Lisp symbol in an editable field.
1307 @deffn Widget function
1308 Allows you to edit a lambda expression, or a function name with completion.
1311 @deffn Widget variable
1312 Allows you to edit a variable name, with completion.
1315 @deffn Widget integer
1316 Allows you to edit an integer in an editable field.
1319 @deffn Widget number
1320 Allows you to edit a number in an editable field.
1323 @deffn Widget boolean
1324 Allows you to edit a boolean. In Lisp this means a variable which is
1325 either @code{nil} meaning false, or non-@code{nil} meaning true.
1329 @node composite, , atoms, Sexp Types
1330 @comment node-name, next, previous, up
1331 @subsection Composite Sexp Widgets
1332 @cindex composite sexp widgets
1334 The syntax for the composite widget is:
1337 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1341 where each @var{component} must be a widget type. Each component widget
1342 will be displayed in the buffer, and will be editable by the user.
1345 The value of a @code{cons} widget is a cons-cell where the @sc{car} is
1346 the value of the first component and the @sc{cdr} is the value of the
1347 second component. There must be exactly two components.
1351 The value of a @code{list} widget is a list containing the value of
1352 each of its component.
1355 @deffn Widget vector
1356 The value of a @code{vector} widget is a vector containing the value of
1357 each of its component.
1360 The above suffice for specifying fixed size lists and vectors. To get
1361 variable length lists and vectors, you can use a @code{choice},
1362 @code{set}, or @code{repeat} widgets together with the @code{:inline}
1363 keywords. If any component of a composite widget has the @code{:inline}
1364 keyword set, its value must be a list which will then be spliced into
1365 the composite. For example, to specify a list whose first element must
1366 be a file name, and whose remaining arguments should either by the
1367 symbol @code{t} or two files, you can use the following widget
1374 :value ("foo" "bar")
1378 The value of a widget of this type will either have the form
1379 @code{(file t)} or @code{(file string string)}.
1381 This concept of inline is probably hard to understand. It was certainly
1382 hard to implement, so instead of confusing you more by trying to explain
1383 it here, I'll just suggest you meditate over it for a while.
1385 @deffn Widget choice
1386 Allows you to edit a sexp which may have one of a fixed set of types.
1387 It is currently implemented with the @code{choice-menu} basic widget,
1388 and has a similar syntax.
1392 Allows you to specify a type which must be a list whose elements all
1393 belong to given set. The elements of the list are not significant.
1394 This is implemented on top of the @code{checklist} basic widget, and has
1398 @deffn Widget repeat
1399 Allows you to specify a variable length list whose members are all of
1400 the same type. Implemented on top of the @code{editable-list} basic
1401 widget, and has a similar syntax.
1404 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1405 @comment node-name, next, previous, up
1407 @cindex properties of widgets
1408 @cindex widget properties
1410 You can examine or set the value of a widget by using the widget object
1411 that was returned by @code{widget-create}.
1413 @defun widget-value widget
1414 Return the current value contained in @var{widget}.
1415 It is an error to call this function on an uninitialized widget.
1418 @defun widget-value-set widget value
1419 Set the value contained in @var{widget} to @var{value}.
1420 It is an error to call this function with an invalid @var{value}.
1423 @strong{Important:} You @emph{must} call @code{widget-setup} after
1424 modifying the value of a widget before the user is allowed to edit the
1425 widget again. It is enough to call @code{widget-setup} once if you
1426 modify multiple widgets. This is currently only necessary if the widget
1427 contains an editing field, but may be necessary for other widgets in the
1430 If your application needs to associate some information with the widget
1431 objects, for example a reference to the item being edited, it can be
1432 done with @code{widget-put} and @code{widget-get}. The property names
1433 must begin with a @samp{:}.
1435 @defun widget-put widget property value
1436 In @var{widget} set @var{property} to @var{value}.
1437 @var{property} should be a symbol, while @var{value} can be anything.
1440 @defun widget-get widget property
1441 In @var{widget} return the value for @var{property}.
1442 @var{property} should be a symbol, the value is what was last set by
1443 @code{widget-put} for @var{property}.
1446 @defun widget-member widget property
1447 Non-@code{nil} if @var{widget} has a value (even @code{nil}) for
1448 property @var{property}.
1451 Occasionally it can be useful to know which kind of widget you have,
1452 i.e.@: the name of the widget type you gave when the widget was created.
1454 @defun widget-type widget
1455 Return the name of @var{widget}, a symbol.
1458 @cindex active widget
1459 @cindex inactive widget
1460 @cindex activate a widget
1461 @cindex deactivate a widget
1462 Widgets can be in two states: active, which means they are modifiable by
1463 the user, or inactive, which means they cannot be modified by the user.
1464 You can query or set the state with the following code:
1467 ;; Examine if @var{widget} is active or not.
1468 (if (widget-apply @var{widget} :active)
1469 (message "Widget is active.")
1470 (message "Widget is inactive.")
1472 ;; Make @var{widget} inactive.
1473 (widget-apply @var{widget} :deactivate)
1475 ;; Make @var{widget} active.
1476 (widget-apply @var{widget} :activate)
1479 A widget is inactive if it, or any of its ancestors (found by
1480 following the @code{:parent} link), have been deactivated. To make sure
1481 a widget is really active, you must therefore activate both it and
1486 (widget-apply widget :activate)
1487 (setq widget (widget-get widget :parent)))
1490 You can check if a widget has been made inactive by examining the value
1491 of the @code{:inactive} keyword. If this is non-@code{nil}, the widget itself
1492 has been deactivated. This is different from using the @code{:active}
1493 keyword, in that the latter tells you if the widget @strong{or} any of
1494 its ancestors have been deactivated. Do not attempt to set the
1495 @code{:inactive} keyword directly. Use the @code{:activate}
1496 @code{:deactivate} keywords instead.
1499 @node Defining New Widgets, Widget Browser, Widget Properties, Top
1500 @comment node-name, next, previous, up
1501 @section Defining New Widgets
1503 @cindex defining new widgets
1505 You can define specialized widgets with @code{define-widget}. It allows
1506 you to create a shorthand for more complex widgets, including specifying
1507 component widgets and new default values for the keyword
1510 @defun define-widget name class doc &rest args
1511 Define a new widget type named @var{name} from @code{class}.
1513 @var{name} and class should both be symbols, @code{class} should be one
1514 of the existing widget types.
1516 The third argument @var{doc} is a documentation string for the widget.
1518 After the new widget has been defined, the following two calls will
1519 create identical widgets:
1524 (widget-create @var{name})
1529 (apply widget-create @var{class} @var{args})
1535 Using @code{define-widget} just stores the definition of the widget type
1536 in the @code{widget-type} property of @var{name}, which is what
1537 @code{widget-create} uses.
1539 If you only want to specify defaults for keywords with no complex
1540 conversions, you can use @code{identity} as your conversion function.
1542 The following additional keyword arguments are useful when defining new
1545 @vindex convert-widget@r{ keyword}
1546 @item :convert-widget
1547 Function to convert a widget type before creating a widget of that
1548 type. It takes a widget type as an argument, and returns the converted
1549 widget type. When a widget is created, this function is called for the
1550 widget type and all the widget's parent types, most derived first.
1552 The following predefined functions can be used here:
1554 @defun widget-types-convert-widget widget
1555 Convert @code{:args} as widget types in @var{widget}.
1558 @defun widget-value-convert-widget widget
1559 Initialize @code{:value} from @code{:args} in @var{widget}.
1562 @vindex copy@r{ keyword}
1564 Function to deep copy a widget type. It takes a shallow copy of the
1565 widget type as an argument (made by @code{copy-sequence}), and returns a
1566 deep copy. The purpose of this is to avoid having different instances
1567 of combined widgets share nested attributes.
1569 The following predefined functions can be used here:
1571 @defun widget-types-copy widget
1572 Copy @code{:args} as widget types in @var{widget}.
1575 @vindex value-to-internal@r{ keyword}
1576 @item :value-to-internal
1577 Function to convert the value to the internal format. The function
1578 takes two arguments, a widget and an external value, and returns the
1579 internal value. The function is called on the present @code{:value}
1580 when the widget is created, and on any value set later with
1581 @code{widget-value-set}.
1583 @vindex value-to-external@r{ keyword}
1584 @item :value-to-external
1585 Function to convert the value to the external format. The function
1586 takes two arguments, a widget and an internal value, and returns the
1587 external value. The function is called on the present @code{:value}
1588 when the widget is created, and on any value set later with
1589 @code{widget-value-set}.
1591 @vindex create@r{ keyword}
1593 Function to create a widget from scratch. The function takes one
1594 argument, a widget type, and creates a widget of that type, inserts it
1595 in the buffer, and returns a widget object.
1597 @vindex delete@r{ keyword}
1599 Function to delete a widget. The function takes one argument, a widget,
1600 and should remove all traces of the widget from the buffer.
1602 The default value is:
1604 @defun widget-default-delete widget
1605 Remove @var{widget} from the buffer.
1606 Delete all @code{:children} and @code{:buttons} in @var{widget}.
1609 In most cases you should not change this value, but instead use
1610 @code{:value-delete} to make any additional cleanup.
1612 @vindex value-create@r{ keyword}
1614 Function to expand the @samp{%v} escape in the format string. It will
1615 be called with the widget as its argument and should insert a
1616 representation of the widget's value in the buffer.
1618 Nested widgets should be listed in @code{:children} or @code{:buttons}
1619 to make sure they are automatically deleted.
1621 @vindex value-delete@r{ keyword}
1623 Should remove the representation of the widget's value from the buffer.
1624 It will be called with the widget as its argument. It doesn't have to
1625 remove the text, but it should release markers and delete nested widgets
1626 if these are not listed in @code{:children} or @code{:buttons}.
1628 @vindex value-get@r{ keyword}
1630 Function to extract the value of a widget, as it is displayed in the
1633 The following predefined function can be used here:
1635 @defun widget-value-value-get widget
1636 Return the @code{:value} property of @var{widget}.
1639 @vindex format-handler@r{ keyword}
1640 @item :format-handler
1641 Function to handle unknown @samp{%} escapes in the format string. It
1642 will be called with the widget and the character that follows the
1643 @samp{%} as arguments. You can set this to allow your widget to handle
1644 non-standard escapes.
1646 @findex widget-default-format-handler
1647 You should end up calling @code{widget-default-format-handler} to handle
1648 unknown escape sequences, which will handle the @samp{%h} and any future
1649 escape sequences, as well as give an error for unknown escapes.
1651 @vindex action@r{ keyword}
1653 Function to handle user initiated events. By default, @code{:notify}
1656 The following predefined function can be used here:
1658 @defun widget-parent-action widget &optional event
1659 Tell @code{:parent} of @var{widget} to handle the @code{:action}.
1660 Optional @var{event} is the event that triggered the action.
1663 @vindex prompt-value@r{ keyword}
1665 Function to prompt for a value in the minibuffer. The function should
1666 take four arguments, @var{widget}, @var{prompt}, @var{value}, and
1667 @var{unbound} and should return a value for widget entered by the user.
1668 @var{prompt} is the prompt to use. @var{value} is the default value to
1669 use, unless @var{unbound} is non-@code{nil}, in which case there is no default
1670 value. The function should read the value using the method most natural
1671 for this widget, and does not have to check that it matches.
1674 If you want to define a new widget from scratch, use the @code{default}
1677 @deffn Widget default
1678 Widget used as a base for other widgets.
1680 It provides most of the functionality that is referred to as ``by
1681 default'' in this text.
1684 @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
1685 @comment node-name, next, previous, up
1686 @section Widget Browser
1687 @cindex widget browser
1689 There is a separate package to browse widgets. This is intended to help
1690 programmers who want to examine the content of a widget. The browser
1691 shows the value of each keyword, but uses links for certain keywords
1692 such as @samp{:parent}, which avoids printing cyclic structures.
1694 @deffn Command widget-browse @var{widget}
1695 Create a widget browser for @var{widget}.
1696 When called interactively, prompt for @var{widget}.
1699 @deffn Command widget-browse-other-window @var{widget}
1700 Create a widget browser for @var{widget} and show it in another window.
1701 When called interactively, prompt for @var{widget}.
1704 @deffn Command widget-browse-at @var{pos}
1705 Create a widget browser for the widget at @var{pos}.
1706 When called interactively, use the position of point.
1709 @node Widget Minor Mode, Utilities, Widget Browser, Top
1710 @comment node-name, next, previous, up
1711 @section Widget Minor Mode
1712 @cindex widget minor mode
1714 There is a minor mode for manipulating widgets in major modes that
1715 don't provide any support for widgets themselves. This is mostly
1716 intended to be useful for programmers doing experiments.
1718 @deffn Command widget-minor-mode
1719 Toggle minor mode for traversing widgets.
1720 With arg, turn widget mode on if and only if arg is positive.
1723 @defvar widget-minor-mode-keymap
1724 Keymap used in @code{widget-minor-mode}.
1727 @node Utilities, Widget Wishlist, Widget Minor Mode, Top
1728 @comment node-name, next, previous, up
1730 @cindex utility functions for widgets
1732 @defun widget-prompt-value widget prompt [ value unbound ]
1733 Prompt for a value matching @var{widget}, using @var{prompt}.
1734 The current value is assumed to be @var{value}, unless @var{unbound} is
1735 non-@code{nil}.@refill
1738 @defun widget-get-sibling widget
1739 Get the item which @var{widget} is assumed to toggle.
1740 This is only meaningful for radio buttons or checkboxes in a list.
1743 @node Widget Wishlist, Index, Utilities, Top
1744 @comment node-name, next, previous, up
1750 It should be possible to add or remove items from a list with @kbd{C-k}
1751 and @kbd{C-o} (suggested by @sc{rms}).
1754 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1755 dash (@samp{-}). The dash should be a button that, when invoked, asks
1756 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1757 the ugly buttons, the dash is my idea).
1760 The @code{menu-choice} tag should be prettier, something like the abbreviated
1764 Finish @code{:tab-order}.
1767 Make indentation work with glyphs and proportional fonts.
1770 Add commands to show overview of object and class hierarchies to the
1774 Find a way to disable mouse highlight for inactive widgets.
1777 Find a way to make glyphs look inactive.
1780 Add @code{property-list} widget.
1783 Add @code{association-list} widget.
1786 Add @code{key-binding} widget.
1789 Add @code{widget} widget for editing widget specifications.
1792 Find clean way to implement variable length list.
1793 See @code{TeX-printer-list} for an explanation.
1796 @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
1799 Add a @code{mailto} widget.
1802 @node Index, , Widget Wishlist, Top
1803 @comment node-name, next, previous, up
1806 This is an alphabetical listing of all concepts, functions, commands,
1807 variables, and widgets described in this manual.
1810 @setchapternewpage odd
1815 arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0