5 @settitle The Emacs Widget Library
12 @node Top, Introduction, (dir), (dir)
13 @comment node-name, next, previous, up
14 @top The Emacs Widget Library
21 * Programming Example::
22 * Setting Up the Buffer::
26 * Defining New Widgets::
30 @node Introduction, User Interface, Top, Top
31 @comment node-name, next, previous, up
34 Most graphical user interface toolkits, such as Motif and XView, provide
35 a number of standard user interface controls (sometimes known as
36 `widgets' or `gadgets'). Emacs doesn't really support anything like
37 this, except for an incredible powerful text ``widget''. On the other
38 hand, Emacs does provide the necessary primitives to implement many
39 other widgets within a text buffer. The @code{widget} package
42 The basic widgets are:
46 Areas of text with an associated action. Intended for hypertext links
49 Like link, but intended for stand-alone buttons.
51 An editable text field. It can be either variable or fixed length.
53 Allows the user to choose one of multiple options from a menu, each
54 option is itself a widget. Only the selected option will be visible in
56 @item radio-button-choice
57 Allows the user to choose one of multiple options by pushing radio
58 buttons. The options are implemented as widgets. All options will be
59 visible in the buffer.
61 A simple constant widget intended to be used in the @code{menu-choice} and
62 @code{radio-button-choice} widgets.
64 An button item only intended for use in choices. When pushed, the user
65 will be asked to select another option from the choice widget.
67 A simple @samp{on}/@samp{off} switch.
69 A checkbox (@samp{[ ]}/@samp{[X]}).
71 Create an editable list. The user can insert or delete items in the
72 list. Each list item is itself a widget.
75 Now of what possible use can support for widgets be in a text editor?
76 I'm glad you asked. The answer is that widgets are useful for
77 implementing forms. A @dfn{form} in emacs is a buffer where the user is
78 supposed to fill out a number of fields, each of which has a specific
79 meaning. The user is not supposed to change or delete any of the text
80 between the fields. Examples of forms in Emacs are the @file{forms}
81 package (of course), the customize buffers, the mail and news compose
82 modes, and the @sc{html} form support in the @file{w3} browser.
84 The advantages for a programmer of using the @code{widget} package to
89 More complex field than just editable text are supported.
91 You can give the user immediate feedback if he enters invalid data in a
92 text field, and sometimes prevent entering invalid data.
94 You can have fixed sized fields, thus allowing multiple field to be
97 It is simple to query or set the value of a field.
99 Editing happens in buffer, not in the mini-buffer.
101 Packages using the library get a uniform look, making them easier for
104 As support for embedded graphics improve, the widget library will
105 extended to support it. This means that your code using the widget
106 library will also use the new graphic features by automatic.
109 In order to minimize the code that is loaded by users who does not
110 create any widgets, the code has been split in two files:
114 This will declare the user variables, define the function
115 @code{widget-define}, and autoload the function @code{widget-create}.
117 Everything else is here, there is no reason to load it explicitly, as
118 it will be autoloaded when needed.
121 @node User Interface, Programming Example, Introduction, Top
122 @comment node-name, next, previous, up
123 @section User Interface
125 A form consist of read only text for documentation and some fields,
126 where each the fields contain two parts, as tag and a value. The tags
127 are used to identify the fields, so the documentation can refer to the
128 foo field, meaning the field tagged with @samp{Foo}. Here is an example
132 Here is some documentation.
134 Name: @i{My Name} @strong{Choose}: This option
135 Address: @i{Some Place
139 See also @b{_other work_} for more information.
141 Numbers: count to three below
142 @b{[INS]} @b{[DEL]} @i{One}
143 @b{[INS]} @b{[DEL]} @i{Eh, two?}
144 @b{[INS]} @b{[DEL]} @i{Five!}
159 @b{[Apply Form]} @b{[Reset Form]}
162 The top level widgets in is example are tagged @samp{Name},
163 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
164 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
165 @samp{[Reset Form]}. There are basically two thing the user can do within
166 a form, namely editing the editable text fields and activating the
169 @subsection Editable Text Fields
171 In the example, the value for the @samp{Name} is most likely displayed
172 in an editable text field, and so are values for each of the members of
173 the @samp{Numbers} list. All the normal Emacs editing operations are
174 available for editing these fields. The only restriction is that each
175 change you make must be contained within a single editable text field.
176 For example, capitalizing all text from the middle of one field to the
177 middle of another field is prohibited.
179 Editing text fields are created by the @code{editable-field} widget.
181 The editing text fields are highlighted with the
182 @code{widget-field-face} face, making them easy to find.
184 @deffn Face widget-field-face
185 Face used for other editing fields.
190 Some portions of the buffer have an associated @dfn{action}, which can
191 be @dfn{activated} by a standard key or mouse command. These portions
192 are called @dfn{buttons}. The default commands for activating a button
197 @deffn Command widget-button-press @var{pos} &optional @var{event}
198 Activate the button at @var{pos}, defaulting to point.
199 If point is not located on a button, activate the binding in
200 @code{widget-global-map} (by default the global map).
204 @deffn Command widget-button-click @var{event}
205 Activate the button at the location of the mouse pointer. If the mouse
206 pointer is located in an editable text field, activate the binding in
207 @code{widget-global-map} (by default the global map).
211 There are several different kind of buttons, all of which are present in
215 @item The Option Field Tags.
216 When you activate one of these buttons, you will be asked to choose
217 between a number of different options. This is how you edit an option
218 field. Option fields are created by the @code{menu-choice} widget. In
219 the example, @samp{@b{Choose}} is an option field tag.
220 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons.
221 Activating these will insert or delete elements from a editable list.
222 The list is created by the @code{editable-list} widget.
223 @item Embedded Buttons.
224 The @samp{@b{_other work_}} is an example of an embedded
225 button. Embedded buttons are not associated with a fields, but can serve
226 any purpose, such as implementing hypertext references. They are
227 usually created by the @code{link} widget.
228 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons.
229 Activating one of these will convert it to the other. This is useful
230 for implementing multiple-choice fields. You can create it wit
231 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons.
232 Only one radio button in a @code{radio-button-choice} widget can be selected at any
233 time. When you push one of the unselected radio buttons, it will be
234 selected and the previous selected radio button will become unselected.
235 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons.
236 These are explicit buttons made with the @code{push-button} widget. The main
237 difference from the @code{link} widget is that the buttons are will be
238 displayed as GUI buttons when possible.
242 To make them easier to locate, buttons are emphasized in the buffer.
244 @deffn Face widget-button-face
245 Face used for buttons.
248 @defopt widget-mouse-face
249 Face used for buttons when the mouse pointer is above it.
252 @subsection Navigation
254 You can use all the normal Emacs commands to move around in a form
255 buffer, plus you will have these additional commands:
259 @deffn Command widget-forward &optional count
260 Move point @var{count} buttons or editing fields forward.
263 @deffn Command widget-backward &optional count
264 Move point @var{count} buttons or editing fields backward.
268 @node Programming Example, Setting Up the Buffer, User Interface, Top
269 @comment node-name, next, previous, up
270 @section Programming Example
272 Here is the code to implement the user interface example (see @ref{User
281 (defvar widget-example-repeat)
283 (defun widget-example ()
284 "Create the widgets from the Widget manual."
286 (switch-to-buffer "*Widget Example*")
287 (kill-all-local-variables)
288 (make-local-variable 'widget-example-repeat)
289 (let ((inhibit-read-only t))
291 (widget-insert "Here is some documentation.\n\nName: ")
292 (widget-create 'editable-field
295 (widget-create 'menu-choice
298 :help-echo "Choose me, please!"
299 :notify (lambda (widget &rest ignore)
300 (message "%s is a good choice!"
301 (widget-value widget)))
302 '(item :tag "This option" :value "This")
303 '(choice-item "That option")
304 '(editable-field :menu-tag "No option" "Thus option"))
305 (widget-insert "Address: ")
306 (widget-create 'editable-field
307 "Some Place\nIn some City\nSome country.")
308 (widget-insert "\nSee also ")
310 :notify (lambda (&rest ignore)
311 (widget-value-set widget-example-repeat
315 (widget-insert " for more information.\n\nNumbers: count to three below\n")
316 (setq widget-example-repeat
317 (widget-create 'editable-list
318 :entry-format "%i %d %v"
319 :notify (lambda (widget &rest ignore)
320 (let ((old (widget-get widget
322 (new (length (widget-value widget))))
324 (widget-put widget ':example-length new)
325 (message "You can count to %d." new))))
326 :value '("One" "Eh, two?" "Five!")
327 '(editable-field :value "three")))
328 (widget-insert "\n\nSelect multiple:\n\n")
329 (widget-create 'checkbox t)
330 (widget-insert " This\n")
331 (widget-create 'checkbox nil)
332 (widget-insert " That\n")
333 (widget-create 'checkbox
334 :notify (lambda (&rest ignore) (message "Tickle"))
336 (widget-insert " Thus\n\nSelect one:\n\n")
337 (widget-create 'radio-button-choice
339 :notify (lambda (widget &rest ignore)
340 (message "You selected %s"
341 (widget-value widget)))
342 '(item "One") '(item "Anthor One.") '(item "A Final One."))
344 (widget-create 'push-button
345 :notify (lambda (&rest ignore)
346 (if (= (length (widget-value widget-example-repeat))
348 (message "Congratulation!")
349 (error "Three was the count!")))
352 (widget-create 'push-button
353 :notify (lambda (&rest ignore)
357 (use-local-map widget-keymap)
361 @node Setting Up the Buffer, Basic Types, Programming Example, Top
362 @comment node-name, next, previous, up
363 @section Setting Up the Buffer
365 Widgets are created with @code{widget-create}, which returns a
366 @dfn{widget} object. This object can be queried and manipulated by
367 other widget functions, until it is deleted with @code{widget-delete}.
368 After the widgets have been created, @code{widget-setup} must be called
371 @defun widget-create type [ keyword argument ]@dots{}
372 Create and return a widget of type @var{type}.
373 The syntax for the @var{type} argument is described in @ref{Basic Types}.
375 The keyword arguments can be used to overwrite the keyword arguments
376 that are part of @var{type}.
379 @defun widget-delete widget
380 Delete @var{widget} and remove it from the buffer.
384 Setup a buffer to support widgets.
386 This should be called after creating all the widgets and before allowing
387 the user to edit them.
391 If you want to insert text outside the widgets in the form, the
392 recommended way to do that is with @code{widget-insert}.
395 Insert the arguments, either strings or characters, at point.
396 The inserted text will be read only.
399 There is a standard widget keymap which you might find useful.
401 @defvr Const widget-keymap
402 A keymap with the global keymap as its parent.@*
403 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
404 @code{widget-backward}, respectively. @kbd{@key{RET}} and @kbd{mouse-2}
405 are bound to @code{widget-button-press} and
406 @code{widget-button-}.@refill
409 @defvar widget-global-map
410 Keymap used by @code{widget-button-press} and @code{widget-button-click}
411 when not on a button. By default this is @code{global-map}.
414 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
415 @comment node-name, next, previous, up
418 The syntax of a type specification is given below:
421 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
425 Where, @var{name} is a widget name, @var{keyword} is the name of a
426 property, @var{argument} is the value of the property, and @var{args}
427 are interpreted in a widget specific way.
429 There following keyword arguments that apply to all widgets:
433 The initial value for widgets of this type.
436 This string will be inserted in the buffer when you create a widget.
437 The following @samp{%} escapes are available:
442 The text inside will be marked as a button.
446 The text inside will be displayed with the face specified by
450 This will be replaces with the buffer representation of the widgets
451 value. What this is depends on the widget type.
454 Insert the string specified by @code{:doc} here.
457 Like @samp{%d}, with the following modifications: If the documentation
458 string is more than one line, it will add a button which will toggle
459 between showing only the first line, and showing the full text.
460 Furthermore, if there is no @code{:doc} property in the widget, it will
461 instead examine the @code{:documentation-property} property. If it is a
462 lambda expression, it will be called with the widget's value as an
463 argument, and the result will be used as the documentation text.
466 Insert the string specified by @code{:tag} here, or the @code{princ}
467 representation of the value if there is no tag.
470 Insert a literal @samp{%}.
474 Face used to highlight text inside %[ %] in the format.
477 The string inserted by the @samp{%d} escape in the format
481 The string inserted by the @samp{%t} escape in the format
485 Name of image to use instead of the string specified by `:tag' on
486 Emacsen that supports it.
489 Message displayed whenever you move to the widget with either
490 @code{widget-forward} or @code{widget-backward}.
493 An integer indicating the absolute number of spaces to indent children
497 An integer indicating how many extra spaces to add to the widget's
498 grandchildren compared to this widget.
501 An integer indicating how many extra spaces to add to the widget's
502 children compared to this widget.
505 A function called each time the widget or a nested widget is changed.
506 The function is called with two or three arguments. The first argument
507 is the widget itself, the second argument is the widget that was
508 changed, and the third argument is the event leading to the change, if
512 Tag used in the menu when the widget is used as an option in a
513 @code{menu-choice} widget.
516 Function used for finding the tag when the widget is used as an option
517 in a @code{menu-choice} widget. By default, the tag used will be either the
518 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
519 representation of the @code{:value} property if not.
522 Should be a function called with two arguments, the widget and a value,
523 and returning non-nil if the widget can represent the specified value.
526 A function which takes a widget as an argument, and return nil if the
527 widgets current value is valid for the widget. Otherwise, it should
528 return the widget containing the invalid data, and set that widgets
529 @code{:error} property to a string explaining the error.
532 Specify the order in which widgets are traversed with
533 @code{widget-forward} or @code{widget-backward}. This is only partially
538 Widgets with tabbing order @code{-1} are ignored.
541 (Unimplemented) When on a widget with tabbing order @var{n}, go to the
542 next widget in the buffer with tabbing order @var{n+1} or @code{nil},
543 whichever comes first.
546 When on a widget with no tabbing order specified, go to the next widget
547 in the buffer with a positive tabbing order, or @code{nil}
551 The parent of a nested widget (e.g. a @code{menu-choice} item or an
552 element of a @code{editable-list} widget).
555 This keyword is only used for members of a @code{radio-button-choice} or
556 @code{checklist}. The value should be a list of extra keyword
557 arguments, which will be used when creating the @code{radio-button} or
558 @code{checkbox} associated with this item.
562 @deffn {User Option} widget-glyph-directory
563 Directory where glyphs are found.
564 Widget will look here for a file with the same name as specified for the
565 image, with either a @samp{.xpm} (if supported) or @samp{.xbm} extension.
568 @deffn{User Option} widget-glyph-enable
569 If non-nil, allow glyphs to appear on displayes where they are supported.
581 * radio-button-choice::
590 @node link, url-link, Basic Types, Basic Types
591 @comment node-name, next, previous, up
592 @subsection The @code{link} Widget
597 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
600 The @var{value}, if present, is used to initialize the @code{:value}
601 property. The value should be a string, which will be inserted in the
604 @node url-link, info-link, link, Basic Types
605 @comment node-name, next, previous, up
606 @subsection The @code{url-link} Widget
611 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
614 When this link is activated, the @sc{www} browser specified by
615 @code{browse-url-browser-function} will be called with @var{url}.
617 @node info-link, push-button, url-link, Basic Types
618 @comment node-name, next, previous, up
619 @subsection The @code{info-link} Widget
624 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
627 When this link is activated, the build-in info browser is started on
630 @node push-button, editable-field, info-link, Basic Types
631 @comment node-name, next, previous, up
632 @subsection The @code{push-button} Widget
637 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
640 The @var{value}, if present, is used to initialize the @code{:value}
641 property. The value should be a string, which will be inserted in the
644 The following extra properties are recognized.
648 The format string used when the push button cannot be displayed
649 graphically. There are two escapes, @code{%s}, which must be present
650 exactly once, will be substituted with the tag, and @code{%%} will be
651 substituted with a singe @samp{%}.
654 By default the tag will be shown in brackets.
656 @node editable-field, text, push-button, Basic Types
657 @comment node-name, next, previous, up
658 @subsection The @code{editable-field} Widget
663 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
666 The @var{value}, if present, is used to initialize the @code{:value}
667 property. The value should be a string, which will be inserted in
668 field. This widget will match all string values.
670 The following extra properties are recognized.
674 The width of the editable field.@*
675 By default the field will reach to the end of the line.
678 Face used for highlighting the editable field. Default is
679 @code{widget-field-face}.
682 Character used to display the value. You can set this to e.g. @code{?*}
683 if the field contains a password or other secret information. By
684 default, the value is not secret.
687 By default the @code{:validate} function will match the content of the
688 field with the value of this attribute. The default value is @code{""}
689 which matches everything.
692 Keymap used in the editable field. The default value is
693 @code{widget-field-keymap}, which allows you to use all the normal
694 editing commands, even if the buffers major mode supress some of them.
695 Pressing return activates the function specified by @code{:activate}.
697 @item :hide-front-space
698 @itemx :hide-rear-space
699 In order to keep track of the editable field, emacs places an invisible
700 space character in front of the field, and for fixed sized fields also
701 in the rear end of the field. For fields that extent to the end of the
702 line, the terminating linefeed serves that purpose instead.
704 Emacs will try to make the spaces intangible when it is safe to do so.
705 Intangible means that the cursor motion commands will skip over the
706 character as if it didn't exist. This is safe to do when the text
707 preceding or following the widget cannot possible change during the
708 lifetime of the @code{editable-field} widget. The preferred way to tell
709 Emacs this, is to add text to the @code{:format} property around the
710 value. For example @code{:format "Tag: %v "}.
712 You can overwrite the internal safety check by setting the
713 @code{:hide-front-space} or @code{:hide-rear-space} properties to
714 non-nil. This is not recommended. For example, @emph{all} text that
715 belongs to a widget (i.e. is created from its @code{:format} string) will
716 change whenever the widget changes its value.
720 @node text, menu-choice, editable-field, Basic Types
721 @comment node-name, next, previous, up
722 @subsection The @code{text} Widget
724 This is just like @code{editable-field}, but intended for multiline text
725 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
726 does not rebind the return key.
728 @node menu-choice, radio-button-choice, text, Basic Types
729 @comment node-name, next, previous, up
730 @subsection The @code{menu-choice} Widget
735 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
738 The @var{type} arguments represents each possible choice. The widgets
739 value of will be the value of the chosen @var{type} argument. This
740 widget will match any value that matches at least one of the specified
741 @var{type} arguments.
745 Widget type used as a fallback when the value does not match any of the
746 specified @var{type} arguments.
749 Set this to nil if you don't want to ignore case when prompting for a
750 choice through the minibuffer.
753 A list whose car is the widget representing the currently chosen type in
757 The current chosen type
763 @node radio-button-choice, item, menu-choice, Basic Types
764 @comment node-name, next, previous, up
765 @subsection The @code{radio-button-choice} Widget
770 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
773 The @var{type} arguments represents each possible choice. The widgets
774 value of will be the value of the chosen @var{type} argument. This
775 widget will match any value that matches at least one of the specified
776 @var{type} arguments.
778 The following extra properties are recognized.
782 This string will be inserted for each entry in the list.
783 The following @samp{%} escapes are available:
786 Replaced with the buffer representation of the @var{type} widget.
788 Replace with the radio button.
790 Insert a literal @samp{%}.
794 A list of keywords to pass to the radio buttons. Useful for setting
795 e.g. the @samp{:help-echo} for each button.
798 The widgets representing the radio buttons.
801 The widgets representing each type.
804 The current chosen type
810 You can add extra radio button items to a @code{radio-button-choice}
811 widget after it has been created with the function
812 @code{widget-radio-add-item}.
814 @defun widget-radio-add-item widget type
815 Add to @code{radio-button-choice} widget @var{widget} a new radio button item of type
819 Please note that such items added after the @code{radio-button-choice}
820 widget has been created will @strong{not} be properly destructed when
821 you call @code{widget-delete}.
823 @node item, choice-item, radio-button-choice, Basic Types
824 @comment node-name, next, previous, up
825 @subsection The @code{item} Widget
830 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
833 The @var{value}, if present, is used to initialize the @code{:value}
834 property. The value should be a string, which will be inserted in the
835 buffer. This widget will only match the specified value.
837 @node choice-item, toggle, item, Basic Types
838 @comment node-name, next, previous, up
839 @subsection The @code{choice-item} Widget
844 ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
847 The @var{value}, if present, is used to initialize the @code{:value}
848 property. The value should be a string, which will be inserted in the
849 buffer as a button. Activating the button of a @code{choice-item} is
850 equivalent to activating the parent widget. This widget will only match
853 @node toggle, checkbox, choice-item, Basic Types
854 @comment node-name, next, previous, up
855 @subsection The @code{toggle} Widget
860 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
863 The widget has two possible states, `on' and `off', which corresponds to
864 a @code{t} or @code{nil} value.
866 The following extra properties are recognized.
870 String representing the `on' state. By default the string @samp{on}.
872 String representing the `off' state. By default the string @samp{off}.
874 Name of a glyph to be used instead of the `:on' text string, on emacsen
877 Name of a glyph to be used instead of the `:off' text string, on emacsen
881 @node checkbox, checklist, toggle, Basic Types
882 @comment node-name, next, previous, up
883 @subsection The @code{checkbox} Widget
885 The widget has two possible states, `selected' and `unselected', which
886 corresponds to a @code{t} or @code{nil} value.
891 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
894 @node checklist, editable-list, checkbox, Basic Types
895 @comment node-name, next, previous, up
896 @subsection The @code{checklist} Widget
901 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
904 The @var{type} arguments represents each checklist item. The widgets
905 value of will be a list containing the value of each ticked @var{type}
906 argument. The checklist widget will match a list whose elements all
907 matches at least one of the specified @var{type} arguments.
909 The following extra properties are recognized.
913 This string will be inserted for each entry in the list.
914 The following @samp{%} escapes are available:
917 Replaced with the buffer representation of the @var{type} widget.
919 Replace with the checkbox.
921 Insert a literal @samp{%}.
925 A list of keywords to pass to the checkboxes. Useful for setting
926 e.g. the @samp{:help-echo} for each checkbox.
929 The widgets representing the checkboxes.
932 The widgets representing each type.
938 @node editable-list, , checklist, Basic Types
939 @comment node-name, next, previous, up
940 @subsection The @code{editable-list} Widget
945 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
948 The value is a list, where each member represent one widget of type
951 The following extra properties are recognized.
955 This string will be inserted for each entry in the list.
956 The following @samp{%} escapes are available:
959 This will be replaced with the buffer representation of the @var{type}
962 Insert the @b{[INS]} button.
964 Insert the @b{[DEL]} button.
966 Insert a literal @samp{%}.
969 @item :insert-button-args
970 A list of keyword arguments to pass to the insert buttons.
972 @item :delete-button-args
973 A list of keyword arguments to pass to the delete buttons.
975 @item :append-button-args
976 A list of keyword arguments to pass to the trailing insert button.
980 The widgets representing the insert and delete buttons.
983 The widgets representing the elements of the list.
986 List whose car is the type of the list elements.
990 @node Sexp Types, Widget Properties, Basic Types, Top
994 A number of widgets for editing s-expressions (lisp types) are also
995 available. These basically fall in three categories: @dfn{atoms},
996 @dfn{composite types}, and @dfn{generic}.
1004 @node generic, atoms, Sexp Types, Sexp Types
1005 @comment node-name, next, previous, up
1006 @subsection The Generic Widget.
1008 The @code{const} and @code{sexp} widgets can contain any lisp
1009 expression. In the case of the @code{const} widget the user is
1010 prohibited from editing edit it, which is mainly useful as a component
1011 of one of the composite widgets.
1013 The syntax for the generic widgets is
1016 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
1019 The @var{value}, if present, is used to initialize the @code{:value}
1020 property and can be any s-expression.
1023 This will display any valid s-expression in an immutable part of the
1028 This will allow you to edit any valid s-expression in an editable buffer
1031 The @code{sexp} widget takes the same keyword arguments as the
1032 @code{editable-field} widget.
1035 @node atoms, composite, generic, Sexp Types
1036 @comment node-name, next, previous, up
1037 @subsection Atomic Sexp Widgets.
1039 The atoms are s-expressions that does not consist of other
1040 s-expressions. A string is an atom, while a list is a composite type.
1041 You can edit the value of an atom with the following widgets.
1043 The syntax for all the atoms are
1046 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
1049 The @var{value}, if present, is used to initialize the @code{:value}
1050 property and must be an expression of the same type as the widget.
1051 I.e. the string widget can only be initialized with a string.
1053 All the atom widgets take the same keyword arguments as the @code{editable-field}
1056 @deffn Widget string
1057 Allows you to edit a string in an editable field.
1061 Allows you to edit a file name in an editable field. You you activate
1062 the tag button, you can edit the file name in the mini-buffer with
1068 If this is set to non-nil, only existing file names will be allowed in
1073 @deffn Widget directory
1074 Allows you to edit a directory name in an editable field.
1075 Similar to the @code{file} widget.
1078 @deffn Widget symbol
1079 Allows you to edit a lisp symbol in an editable field.
1082 @deffn Widget integer
1083 Allows you to edit an integer in an editable field.
1086 @deffn Widget number
1087 Allows you to edit a number in an editable field.
1090 @deffn Widget boolean
1091 Allows you to edit a boolean. In lisp this means a variable which is
1092 either nil meaning false, or non-nil meaning true.
1096 @node composite, , atoms, Sexp Types
1097 @comment node-name, next, previous, up
1098 @subsection Composite Sexp Widgets.
1100 The syntax for the composite are
1103 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1106 Where each @var{component} must be a widget type. Each component widget
1107 will be displayed in the buffer, and be editable to the user.
1110 The value of a @code{cons} widget is a cons-cell where the car is the
1111 value of the first component and the cdr is the value of the second
1112 component. There must be exactly two components.
1116 The value of a @code{lisp} widget is a list containing the value of
1117 each of its component.
1120 @deffn Widget vector
1121 The value of a @code{vector} widget is a vector containing the value of
1122 each of its component.
1125 The above suffice for specifying fixed size lists and vectors. To get
1126 variable length lists and vectors, you can use a @code{choice},
1127 @code{set} or @code{repeat} widgets together with the @code{:inline}
1128 keywords. If any component of a composite widget has the @code{:inline}
1129 keyword set, its value must be a list which will then be spliced into
1130 the composite. For example, to specify a list whose first element must
1131 be a file name, and whose remaining arguments should either by the
1132 symbol @code{t} or two files, you can use the following widget
1139 :value ("foo" "bar")
1143 The value of a widget of this type will either have the form
1144 @samp{(file t)} or @code{(file string string)}.
1146 This concept of inline is probably hard to understand. It was certainly
1147 hard to implement so instead of confuse you more by trying to explain it
1148 here, I'll just suggest you meditate over it for a while.
1150 @deffn Widget choice
1151 Allows you to edit a sexp which may have one of fixed set of types. It
1152 is currently implemented with the @code{choice-menu} basic widget, and
1153 has a similar syntax.
1157 Allows you to specify a type which must be a list whose elements all
1158 belong to given set. The elements of the list is not significant. This
1159 is implemented on top of the @code{checklist} basic widget, and has a
1163 @deffn Widget repeat
1164 Allows you to specify a variable length list whose members are all of
1165 the same type. Implemented on top of the `editable-list' basic widget,
1166 and has a similar syntax.
1169 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1170 @comment node-name, next, previous, up
1173 You can examine or set the value of a widget by using the widget object
1174 that was returned by @code{widget-create}.
1176 @defun widget-value widget
1177 Return the current value contained in @var{widget}.
1178 It is an error to call this function on an uninitialized widget.
1181 @defun widget-value-set widget value
1182 Set the value contained in @var{widget} to @var{value}.
1183 It is an error to call this function with an invalid @var{value}.
1186 @strong{Important:} You @emph{must} call @code{widget-setup} after
1187 modifying the value of a widget before the user is allowed to edit the
1188 widget again. It is enough to call @code{widget-setup} once if you
1189 modify multiple widgets. This is currently only necessary if the widget
1190 contains an editing field, but may be necessary for other widgets in the
1193 If your application needs to associate some information with the widget
1194 objects, for example a reference to the item being edited, it can be
1195 done with @code{widget-put} and @code{widget-get}. The property names
1196 must begin with a @samp{:}.
1198 @defun widget-put widget property value
1199 In @var{widget} set @var{property} to @var{value}.
1200 @var{property} should be a symbol, while @var{value} can be anything.
1203 @defun widget-get widget property
1204 In @var{widget} return the value for @var{property}.
1205 @var{property} should be a symbol, the value is what was last set by
1206 @code{widget-put} for @var{property}.
1209 @defun widget-member widget property
1210 Non-nil if @var{widget} has a value (even nil) for property @var{property}.
1213 Occasionally it can be useful to know which kind of widget you have,
1214 i.e. the name of the widget type you gave when the widget was created.
1216 @defun widget-type widget
1217 Return the name of @var{widget}, a symbol.
1220 Widgets can be in two states: active, which means they are modifiable by
1221 the user, or inactive, which means they cannot be modified by the user.
1222 You can query or set the state with the following code:
1225 ;; Examine if @var{widget} is active or not.
1226 (if (widget-apply @var{widget} :active)
1227 (message "Widget is active.")
1228 (message "Widget is inactive.")
1230 ;; Make @var{widget} inactive.
1231 (widget-apply @var{widget} :deactivate)
1233 ;; Make @var{widget} active.
1234 (widget-apply @var{widget} :activate)
1237 A widget is inactive if itself, or any of its ancestors (found by
1238 following the @code{:parent} link) have been deactivated. To make sure
1239 a widget is really active, you must therefore activate both itself, and
1244 (widget-apply widget :activate)
1245 (setq widget (widget-get widget :parent)))
1248 You can check if a widget has been made inactive by examining the value
1249 of @code{:inactive} keyword. If this is non-nil, the widget itself has
1250 been deactivated. This is different from using the @code{:active}
1251 keyword, in that the later tell you if the widget @strong{or} any of its
1252 ancestors have been deactivated. Do not attempt to set the
1253 @code{:inactive} keyword directly. Use the @code{:activate}
1254 @code{:deactivated} keywords instead.
1257 @node Defining New Widgets, Widget Wishlist., Widget Properties, Top
1258 @comment node-name, next, previous, up
1259 @section Defining New Widgets
1261 You can define specialized widgets with @code{define-widget}. It allows
1262 you to create a shorthand for more complex widgets, including specifying
1263 component widgets and default new default values for the keyword
1266 @defun widget-define name class doc &rest args
1267 Define a new widget type named @var{name} from @code{class}.
1269 @var{name} and class should both be symbols, @code{class} should be one
1270 of the existing widget types.
1272 The third argument @var{DOC} is a documentation string for the widget.
1274 After the new widget has been defined, the following two calls will
1275 create identical widgets:
1280 (widget-create @var{name})
1285 (apply widget-create @var{class} @var{args})
1291 Using @code{widget-define} does just store the definition of the widget
1292 type in the @code{widget-type} property of @var{name}, which is what
1293 @code{widget-create} uses.
1295 If you just want to specify defaults for keywords with no complex
1296 conversions, you can use @code{identity} as your conversion function.
1298 The following additional keyword arguments are useful when defining new
1301 @item :convert-widget
1302 Function to convert a widget type before creating a widget of that
1303 type. It takes a widget type as an argument, and returns the converted
1304 widget type. When a widget is created, this function is called for the
1305 widget type and all the widgets parent types, most derived first.
1307 @item :value-to-internal
1308 Function to convert the value to the internal format. The function
1309 takes two arguments, a widget and an external value, and returns the
1310 internal value. The function is called on the present @code{:value}
1311 when the widget is created, and on any value set later with
1312 @code{widget-value-set}.
1314 @item :value-to-external
1315 Function to convert the value to the external format. The function
1316 takes two arguments, a widget and an internal value, and returns the
1317 internal value. The function is called on the present @code{:value}
1318 when the widget is created, and on any value set later with
1319 @code{widget-value-set}.
1322 Function to create a widget from scratch. The function takes one
1323 argument, a widget type, and create a widget of that type, insert it in
1324 the buffer, and return a widget object.
1327 Function to delete a widget. The function takes one argument, a widget,
1328 and should remove all traces of the widget from the buffer.
1331 Function to expand the @samp{%v} escape in the format string. It will
1332 be called with the widget as its argument. Should
1333 insert a representation of the widgets value in the buffer.
1336 Should remove the representation of the widgets value from the buffer.
1337 It will be called with the widget as its argument. It doesn't have to
1338 remove the text, but it should release markers and delete nested widgets
1339 if such has been used.
1341 @item :format-handler
1342 Function to handle unknown @samp{%} escapes in the format string. It
1343 will be called with the widget and the escape character as arguments.
1344 You can set this to allow your widget to handle non-standard escapes.
1346 You should end up calling @code{widget-default-format-handler} to handle
1347 unknown escape sequences, which will handle the @samp{%h} and any future
1348 escape sequences, as well as give an error for unknown escapes.
1351 If you want to define a new widget from scratch, use the @code{default}
1354 @deffn Widget default [ keyword argument ]
1355 Widget used as a base for other widgets.
1357 It provides most of the functionality that is referred to as ``by
1358 default'' in this text.
1361 @node Widget Wishlist., , Defining New Widgets, Top
1362 @comment node-name, next, previous, up
1367 It should be possible to add or remove items from a list with @kbd{C-k}
1368 and @kbd{C-o} (suggested by @sc{rms}).
1371 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1372 dash (@samp{-}). The dash should be a button that, when activated, ask
1373 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1374 the ugly buttons, the dash is my idea).
1377 Widgets such as @code{file} and @code{symbol} should prompt with completion.
1380 The @code{menu-choice} tag should be prettier, something like the abbreviated
1384 The functions used in many widgets, like
1385 @code{widget-item-convert-widget}, should not have names that are
1386 specific to the first widget where I happended to use them.
1389 Flag to make @code{widget-move} skip a specified button.
1392 Document `helper' functions for defining new widgets.
1395 Activate the item this is below the mouse when the button is
1396 released, not the item this is below the mouse when the button is
1397 pressed. Dired and grep gets this right. Give feedback if possible.
1400 Use @samp{@@deffn Widget} to document widgets.
1403 Document global keywords in one place.
1405 Document keywords particular to a specific widget in the widget
1408 Document the `default' widget first.
1410 Split, when needed, keywords into those useful for normal
1411 customization, those primarily useful when deriving, and those who
1412 represent runtime information.
1415 Figure out terminology and @sc{api} for the class/type/object/super
1418 Perhaps the correct model is delegation?
1421 Document @code{widget-browse}.
1424 Make indentation work with glyphs and propertional fonts.
1427 Add object and class hierarchies to the browser.