3 @c $Id: widget.texi,v 1.83 1997/03/05 16:43:09 abraham Exp $
7 @settitle The Emacs Widget Library
14 @node Top, Introduction, (dir), (dir)
15 @comment node-name, next, previous, up
16 @top The Emacs Widget Library
23 * Programming Example::
24 * Setting Up the Buffer::
28 * Defining New Widgets::
32 @node Introduction, User Interface, Top, Top
33 @comment node-name, next, previous, up
36 Most graphical user interface toolkits, such as Motif and XView, provide
37 a number of standard user interface controls (sometimes known as
38 `widgets' or `gadgets'). Emacs doesn't really support anything like
39 this, except for an incredible powerful text ``widget''. On the other
40 hand, Emacs does provide the necessary primitives to implement many
41 other widgets within a text buffer. The @code{widget} package
44 The basic widgets are:
48 Areas of text with an associated action. Intended for hypertext links
51 Like link, but intended for stand-alone buttons.
53 An editable text field. It can be either variable or fixed length.
55 Allows the user to choose one of multiple options from a menu, each
56 option is itself a widget. Only the selected option will be visible in
58 @item radio-button-choice
59 Allows the user to choose one of multiple options by pushing radio
60 buttons. The options are implemented as widgets. All options will be
61 visible in the buffer.
63 A simple constant widget intended to be used in the @code{menu-choice} and
64 @code{radio-button-choice} widgets.
66 An button item only intended for use in choices. When pushed, the user
67 will be asked to select another option from the choice widget.
69 A simple @samp{on}/@samp{off} switch.
71 A checkbox (@samp{[ ]}/@samp{[X]}).
73 Create an editable list. The user can insert or delete items in the
74 list. Each list item is itself a widget.
77 Now of what possible use can support for widgets be in a text editor?
78 I'm glad you asked. The answer is that widgets are useful for
79 implementing forms. A @dfn{form} in emacs is a buffer where the user is
80 supposed to fill out a number of fields, each of which has a specific
81 meaning. The user is not supposed to change or delete any of the text
82 between the fields. Examples of forms in Emacs are the @file{forms}
83 package (of course), the customize buffers, the mail and news compose
84 modes, and the @sc{html} form support in the @file{w3} browser.
86 The advantages for a programmer of using the @code{widget} package to
91 More complex field than just editable text are supported.
93 You can give the user immediate feedback if he enters invalid data in a
94 text field, and sometimes prevent entering invalid data.
96 You can have fixed sized fields, thus allowing multiple field to be
99 It is simple to query or set the value of a field.
101 Editing happens in buffer, not in the mini-buffer.
103 Packages using the library get a uniform look, making them easier for
106 As support for embedded graphics improve, the widget library will
107 extended to support it. This means that your code using the widget
108 library will also use the new graphic features by automatic.
111 In order to minimize the code that is loaded by users who does not
112 create any widgets, the code has been split in two files:
116 This will declare the user variables, define the function
117 @code{widget-define}, and autoload the function @code{widget-create}.
119 Everything else is here, there is no reason to load it explicitly, as
120 it will be autoloaded when needed.
123 @node User Interface, Programming Example, Introduction, Top
124 @comment node-name, next, previous, up
125 @section User Interface
127 A form consist of read only text for documentation and some fields,
128 where each the fields contain two parts, as tag and a value. The tags
129 are used to identify the fields, so the documentation can refer to the
130 foo field, meaning the field tagged with @samp{Foo}. Here is an example
134 Here is some documentation.
136 Name: @i{My Name} @strong{Choose}: This option
137 Address: @i{Some Place
141 See also @b{_other work_} for more information.
143 Numbers: count to three below
144 @b{[INS]} @b{[DEL]} @i{One}
145 @b{[INS]} @b{[DEL]} @i{Eh, two?}
146 @b{[INS]} @b{[DEL]} @i{Five!}
161 @b{[Apply Form]} @b{[Reset Form]}
164 The top level widgets in is example are tagged @samp{Name},
165 @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
166 @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
167 @samp{[Reset Form]}. There are basically two thing the user can do within
168 a form, namely editing the editable text fields and activating the
171 @subsection Editable Text Fields
173 In the example, the value for the @samp{Name} is most likely displayed
174 in an editable text field, and so are values for each of the members of
175 the @samp{Numbers} list. All the normal Emacs editing operations are
176 available for editing these fields. The only restriction is that each
177 change you make must be contained within a single editable text field.
178 For example, capitalizing all text from the middle of one field to the
179 middle of another field is prohibited.
181 Editing text fields are created by the @code{editable-field} widget.
183 The editing text fields are highlighted with the
184 @code{widget-field-face} face, making them easy to find.
186 @deffn Face widget-field-face
187 Face used for other editing fields.
192 Some portions of the buffer have an associated @dfn{action}, which can
193 be @dfn{activated} by a standard key or mouse command. These portions
194 are called @dfn{buttons}. The default commands for activating a button
199 @deffn Command widget-button-press @var{pos} &optional @var{event}
200 Activate the button at @var{pos}, defaulting to point.
201 If point is not located on a button, activate the binding in
202 @code{widget-global-map} (by default the global map).
206 @deffn Command widget-button-click @var{event}
207 Activate the button at the location of the mouse pointer. If the mouse
208 pointer is located in an editable text field, activate the binding in
209 @code{widget-global-map} (by default the global map).
213 There are several different kind of buttons, all of which are present in
217 @item The Option Field Tags.
218 When you activate one of these buttons, you will be asked to choose
219 between a number of different options. This is how you edit an option
220 field. Option fields are created by the @code{menu-choice} widget. In
221 the example, @samp{@b{Choose}} is an option field tag.
222 @item The @samp{@b{[INS]}} and @samp{@b{[DEL]}} buttons.
223 Activating these will insert or delete elements from a editable list.
224 The list is created by the @code{editable-list} widget.
225 @item Embedded Buttons.
226 The @samp{@b{_other work_}} is an example of an embedded
227 button. Embedded buttons are not associated with a fields, but can serve
228 any purpose, such as implementing hypertext references. They are
229 usually created by the @code{link} widget.
230 @item The @samp{@b{[ ]}} and @samp{@b{[X]}} buttons.
231 Activating one of these will convert it to the other. This is useful
232 for implementing multiple-choice fields. You can create it wit
233 @item The @samp{@b{( )}} and @samp{@b{(*)}} buttons.
234 Only one radio button in a @code{radio-button-choice} widget can be selected at any
235 time. When you push one of the unselected radio buttons, it will be
236 selected and the previous selected radio button will become unselected.
237 @item The @samp{@b{[Apply Form]}} @samp{@b{[Reset Form]}} buttons.
238 These are explicit buttons made with the @code{push-button} widget. The main
239 difference from the @code{link} widget is that the buttons are will be
240 displayed as GUI buttons when possible.
244 To make them easier to locate, buttons are emphasized in the buffer.
246 @deffn Face widget-button-face
247 Face used for buttons.
250 @defopt widget-mouse-face
251 Face used for buttons when the mouse pointer is above it.
254 @subsection Navigation
256 You can use all the normal Emacs commands to move around in a form
257 buffer, plus you will have these additional commands:
261 @deffn Command widget-forward &optional count
262 Move point @var{count} buttons or editing fields forward.
265 @deffn Command widget-backward &optional count
266 Move point @var{count} buttons or editing fields backward.
270 @node Programming Example, Setting Up the Buffer, User Interface, Top
271 @comment node-name, next, previous, up
272 @section Programming Example
274 Here is the code to implement the user interface example (see @ref{User
283 (defvar widget-example-repeat)
285 (defun widget-example ()
286 "Create the widgets from the Widget manual."
288 (switch-to-buffer "*Widget Example*")
289 (kill-all-local-variables)
290 (make-local-variable 'widget-example-repeat)
291 (let ((inhibit-read-only t))
293 (widget-insert "Here is some documentation.\n\nName: ")
294 (widget-create 'editable-field
297 (widget-create 'menu-choice
300 :help-echo "Choose me, please!"
301 :notify (lambda (widget &rest ignore)
302 (message "%s is a good choice!"
303 (widget-value widget)))
304 '(item :tag "This option" :value "This")
305 '(choice-item "That option")
306 '(editable-field :menu-tag "No option" "Thus option"))
307 (widget-insert "Address: ")
308 (widget-create 'editable-field
309 "Some Place\nIn some City\nSome country.")
310 (widget-insert "\nSee also ")
312 :notify (lambda (&rest ignore)
313 (widget-value-set widget-example-repeat
317 (widget-insert " for more information.\n\nNumbers: count to three below\n")
318 (setq widget-example-repeat
319 (widget-create 'editable-list
320 :entry-format "%i %d %v"
321 :notify (lambda (widget &rest ignore)
322 (let ((old (widget-get widget
324 (new (length (widget-value widget))))
326 (widget-put widget ':example-length new)
327 (message "You can count to %d." new))))
328 :value '("One" "Eh, two?" "Five!")
329 '(editable-field :value "three")))
330 (widget-insert "\n\nSelect multiple:\n\n")
331 (widget-create 'checkbox t)
332 (widget-insert " This\n")
333 (widget-create 'checkbox nil)
334 (widget-insert " That\n")
335 (widget-create 'checkbox
336 :notify (lambda (&rest ignore) (message "Tickle"))
338 (widget-insert " Thus\n\nSelect one:\n\n")
339 (widget-create 'radio-button-choice
341 :notify (lambda (widget &rest ignore)
342 (message "You selected %s"
343 (widget-value widget)))
344 '(item "One") '(item "Anthor One.") '(item "A Final One."))
346 (widget-create 'push-button
347 :notify (lambda (&rest ignore)
348 (if (= (length (widget-value widget-example-repeat))
350 (message "Congratulation!")
351 (error "Three was the count!")))
354 (widget-create 'push-button
355 :notify (lambda (&rest ignore)
359 (use-local-map widget-keymap)
363 @node Setting Up the Buffer, Basic Types, Programming Example, Top
364 @comment node-name, next, previous, up
365 @section Setting Up the Buffer
367 Widgets are created with @code{widget-create}, which returns a
368 @dfn{widget} object. This object can be queried and manipulated by
369 other widget functions, until it is deleted with @code{widget-delete}.
370 After the widgets have been created, @code{widget-setup} must be called
373 @defun widget-create type [ keyword argument ]@dots{}
374 Create and return a widget of type @var{type}.
375 The syntax for the @var{type} argument is described in @ref{Basic Types}.
377 The keyword arguments can be used to overwrite the keyword arguments
378 that are part of @var{type}.
381 @defun widget-delete widget
382 Delete @var{widget} and remove it from the buffer.
386 Setup a buffer to support widgets.
388 This should be called after creating all the widgets and before allowing
389 the user to edit them.
393 If you want to insert text outside the widgets in the form, the
394 recommended way to do that is with @code{widget-insert}.
397 Insert the arguments, either strings or characters, at point.
398 The inserted text will be read only.
401 There is a standard widget keymap which you might find useful.
403 @defvr Const widget-keymap
404 A keymap with the global keymap as its parent.@*
405 @key{TAB} and @kbd{C-@key{TAB}} are bound to @code{widget-forward} and
406 @code{widget-backward}, respectively. @kbd{@key{RET}} and @kbd{mouse-2}
407 are bound to @code{widget-button-press} and
408 @code{widget-button-}.@refill
411 @defvar widget-global-map
412 Keymap used by @code{widget-button-press} and @code{widget-button-click}
413 when not on a button. By default this is @code{global-map}.
416 @node Basic Types, Sexp Types, Setting Up the Buffer, Top
417 @comment node-name, next, previous, up
420 The syntax of a type specification is given below:
423 NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
427 Where, @var{name} is a widget name, @var{keyword} is the name of a
428 property, @var{argument} is the value of the property, and @var{args}
429 are interpreted in a widget specific way.
431 There following keyword arguments that apply to all widgets:
435 The initial value for widgets of this type.
438 This string will be inserted in the buffer when you create a widget.
439 The following @samp{%} escapes are available:
444 The text inside will be marked as a button.
448 The text inside will be displayed with the face specified by
452 This will be replaces with the buffer representation of the widgets
453 value. What this is depends on the widget type.
456 Insert the string specified by @code{:doc} here.
459 Like @samp{%d}, with the following modifications: If the documentation
460 string is more than one line, it will add a button which will toggle
461 between showing only the first line, and showing the full text.
462 Furthermore, if there is no @code{:doc} property in the widget, it will
463 instead examine the @code{:documentation-property} property. If it is a
464 lambda expression, it will be called with the widget's value as an
465 argument, and the result will be used as the documentation text.
468 Insert the string specified by @code{:tag} here, or the @code{princ}
469 representation of the value if there is no tag.
472 Insert a literal @samp{%}.
476 Face used to highlight text inside %[ %] in the format.
479 The string inserted by the @samp{%d} escape in the format
483 The string inserted by the @samp{%t} escape in the format
487 Name of image to use instead of the string specified by `:tag' on
488 Emacsen that supports it.
491 Message displayed whenever you move to the widget with either
492 @code{widget-forward} or @code{widget-backward}.
495 An integer indicating the absolute number of spaces to indent children
499 An integer indicating how many extra spaces to add to the widget's
500 grandchildren compared to this widget.
503 An integer indicating how many extra spaces to add to the widget's
504 children compared to this widget.
507 A function called each time the widget or a nested widget is changed.
508 The function is called with two or three arguments. The first argument
509 is the widget itself, the second argument is the widget that was
510 changed, and the third argument is the event leading to the change, if
514 Tag used in the menu when the widget is used as an option in a
515 @code{menu-choice} widget.
518 Function used for finding the tag when the widget is used as an option
519 in a @code{menu-choice} widget. By default, the tag used will be either the
520 @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
521 representation of the @code{:value} property if not.
524 Should be a function called with two arguments, the widget and a value,
525 and returning non-nil if the widget can represent the specified value.
528 A function which takes a widget as an argument, and return nil if the
529 widgets current value is valid for the widget. Otherwise, it should
530 return the widget containing the invalid data, and set that widgets
531 @code{:error} property to a string explaining the error.
534 The parent of a nested widget (e.g. a @code{menu-choice} item or an element of a
535 @code{editable-list} widget).
538 @deffn {User Option} widget-glyph-directory
539 Directory where glyphs are found.
540 Widget will look here for a file with the same name as specified for the
541 image, with either a @samp{.xpm} (if supported) or @samp{.xbm} extension.
544 @deffn{User Option} widget-glyph-enable
545 If non-nil, allow glyphs to appear on displayes where they are supported.
557 * radio-button-choice::
566 @node link, url-link, Basic Types, Basic Types
567 @comment node-name, next, previous, up
568 @subsection The @code{link} Widget
573 TYPE ::= (link [KEYWORD ARGUMENT]... [ VALUE ])
576 The @var{value}, if present, is used to initialize the @code{:value}
577 property. The value should be a string, which will be inserted in the
580 @node url-link, info-link, link, Basic Types
581 @comment node-name, next, previous, up
582 @subsection The @code{url-link} Widget
587 TYPE ::= (url-link [KEYWORD ARGUMENT]... URL)
590 When this link is activated, the @sc{www} browser specified by
591 @code{browse-url-browser-function} will be called with @var{url}.
593 @node info-link, push-button, url-link, Basic Types
594 @comment node-name, next, previous, up
595 @subsection The @code{info-link} Widget
600 TYPE ::= (info-link [KEYWORD ARGUMENT]... ADDRESS)
603 When this link is activated, the build-in info browser is started on
606 @node push-button, editable-field, info-link, Basic Types
607 @comment node-name, next, previous, up
608 @subsection The @code{push-button} Widget
613 TYPE ::= (push-button [KEYWORD ARGUMENT]... [ VALUE ])
616 The @var{value}, if present, is used to initialize the @code{:value}
617 property. The value should be a string, which will be inserted in the
620 @node editable-field, text, push-button, Basic Types
621 @comment node-name, next, previous, up
622 @subsection The @code{editable-field} Widget
627 TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
630 The @var{value}, if present, is used to initialize the @code{:value}
631 property. The value should be a string, which will be inserted in
632 field. This widget will match all string values.
634 The following extra properties are recognized.
638 The width of the editable field.@*
639 By default the field will reach to the end of the line.
642 Face used for highlighting the editable field. Default is
643 @code{widget-field-face}.
646 Character used to display the value. You can set this to e.g. @code{?*}
647 if the field contains a password or other secret information. By
648 default, the value is not secret.
651 By default the @code{:validate} function will match the content of the
652 field with the value of this attribute. The default value is @code{""}
653 which matches everything.
656 Keymap used in the editable field. The default value is
657 @code{widget-field-keymap}, which allows you to use all the normal
658 editing commands, even if the buffers major mode supress some of them.
659 Pressing return activates the function specified by @code{:activate}.
661 @item :hide-front-space
662 @itemx :hide-rear-space
663 In order to keep track of the editable field, emacs places an invisible
664 space character in front of the field, and for fixed sized fields also
665 in the rear end of the field. For fields that extent to the end of the
666 line, the terminating linefeed serves that purpose instead.
668 Emacs will try to make the spaces intangible when it is safe to do so.
669 Intangible means that the cursor motion commands will skip over the
670 character as if it didn't exist. This is safe to do when the text
671 preceding or following the widget cannot possible change during the
672 lifetime of the @code{editable-field} widget. The preferred way to tell
673 Emacs this, is to add text to the @code{:format} property around the
674 value. For example @code{:format "Tag: %v "}.
676 You can overwrite the internal safety check by setting the
677 @code{:hide-front-space} or @code{:hide-rear-space} properties to
678 non-nil. This is not recommended. For example, @emph{all} text that
679 belongs to a widget (i.e. is created from its @code{:format} string) will
680 change whenever the widget changes its value.
684 @node text, menu-choice, editable-field, Basic Types
685 @comment node-name, next, previous, up
686 @subsection The @code{text} Widget
688 This is just like @code{editable-field}, but intended for multiline text
689 fields. The default @code{:keymap} is @code{widget-text-keymap}, which
690 does not rebind the return key.
692 @node menu-choice, radio-button-choice, text, Basic Types
693 @comment node-name, next, previous, up
694 @subsection The @code{menu-choice} Widget
699 TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
702 The @var{type} arguments represents each possible choice. The widgets
703 value of will be the value of the chosen @var{type} argument. This
704 widget will match any value that matches at least one of the specified
705 @var{type} arguments.
709 Widget type used as a fallback when the value does not match any of the
710 specified @var{type} arguments.
713 Set this to nil if you don't want to ignore case when prompting for a
714 choice through the minibuffer.
717 A list whose car is the widget representing the currently chosen type in
721 The current chosen type
727 @node radio-button-choice, item, menu-choice, Basic Types
728 @comment node-name, next, previous, up
729 @subsection The @code{radio-button-choice} Widget
734 TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]... TYPE ... )
737 The @var{type} arguments represents each possible choice. The widgets
738 value of will be the value of the chosen @var{type} argument. This
739 widget will match any value that matches at least one of the specified
740 @var{type} arguments.
742 The following extra properties are recognized.
746 This string will be inserted for each entry in the list.
747 The following @samp{%} escapes are available:
750 Replaced with the buffer representation of the @var{type} widget.
752 Replace with the radio button.
754 Insert a literal @samp{%}.
758 The widgets representing the radio buttons.
761 The widgets representing each type.
764 The current chosen type
770 You can add extra radio button items to a @code{radio-button-choice}
771 widget after it has been created with the function
772 @code{widget-radio-add-item}.
774 @defun widget-radio-add-item widget type
775 Add to @code{radio-button-choice} widget @var{widget} a new radio button item of type
779 Please note that such items added after the @code{radio-button-choice}
780 widget has been created will @strong{not} be properly destructed when
781 you call @code{widget-delete}.
783 @node item, choice-item, radio-button-choice, Basic Types
784 @comment node-name, next, previous, up
785 @subsection The @code{item} Widget
790 ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
793 The @var{value}, if present, is used to initialize the @code{:value}
794 property. The value should be a string, which will be inserted in the
795 buffer. This widget will only match the specified value.
797 @node choice-item, toggle, item, Basic Types
798 @comment node-name, next, previous, up
799 @subsection The @code{choice-item} Widget
804 ITEM ::= (choice-item [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 the
809 buffer as a button. Activating the button of a @code{choice-item} is
810 equivalent to activating the parent widget. This widget will only match
813 @node toggle, checkbox, choice-item, Basic Types
814 @comment node-name, next, previous, up
815 @subsection The @code{toggle} Widget
820 TYPE ::= (toggle [KEYWORD ARGUMENT]...)
823 The widget has two possible states, `on' and `off', which corresponds to
824 a @code{t} or @code{nil} value.
826 The following extra properties are recognized.
830 String representing the `on' state. By default the string @samp{on}.
832 String representing the `off' state. By default the string @samp{off}.
834 Name of a glyph to be used instead of the `:on' text string, on emacsen
837 Name of a glyph to be used instead of the `:off' text string, on emacsen
841 @node checkbox, checklist, toggle, Basic Types
842 @comment node-name, next, previous, up
843 @subsection The @code{checkbox} Widget
845 The widget has two possible states, `selected' and `unselected', which
846 corresponds to a @code{t} or @code{nil} value.
851 TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
854 @node checklist, editable-list, checkbox, Basic Types
855 @comment node-name, next, previous, up
856 @subsection The @code{checklist} Widget
861 TYPE ::= (checklist [KEYWORD ARGUMENT]... TYPE ... )
864 The @var{type} arguments represents each checklist item. The widgets
865 value of will be a list containing the value of each ticked @var{type}
866 argument. The checklist widget will match a list whose elements all
867 matches at least one of the specified @var{type} arguments.
869 The following extra properties are recognized.
873 This string will be inserted for each entry in the list.
874 The following @samp{%} escapes are available:
877 Replaced with the buffer representation of the @var{type} widget.
879 Replace with the checkbox.
881 Insert a literal @samp{%}.
885 The widgets representing the checkboxes.
888 The widgets representing each type.
894 @node editable-list, , checklist, Basic Types
895 @comment node-name, next, previous, up
896 @subsection The @code{editable-list} Widget
901 TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
904 The value is a list, where each member represent one widget of type
907 The following extra properties are recognized.
911 This string will be inserted for each entry in the list.
912 The following @samp{%} escapes are available:
915 This will be replaced with the buffer representation of the @var{type}
918 Insert the @b{[INS]} button.
920 Insert the @b{[DEL]} button.
922 Insert a literal @samp{%}.
926 The widgets representing the insert and delete buttons.
929 The widgets representing the elements of the list.
932 List whose car is the type of the list elements.
936 @node Sexp Types, Widget Properties, Basic Types, Top
940 A number of widgets for editing s-expressions (lisp types) are also
941 available. These basically fall in three categories: @dfn{atoms},
942 @dfn{composite types}, and @dfn{generic}.
950 @node generic, atoms, Sexp Types, Sexp Types
951 @comment node-name, next, previous, up
952 @subsection The Generic Widget.
954 The @code{const} and @code{sexp} widgets can contain any lisp
955 expression. In the case of the @code{const} widget the user is
956 prohibited from editing edit it, which is mainly useful as a component
957 of one of the composite widgets.
959 The syntax for the generic widgets is
962 TYPE ::= (const [KEYWORD ARGUMENT]... [ VALUE ])
965 The @var{value}, if present, is used to initialize the @code{:value}
966 property and can be any s-expression.
969 This will display any valid s-expression in an immutable part of the
974 This will allow you to edit any valid s-expression in an editable buffer
977 The @code{sexp} widget takes the same keyword arguments as the
978 @code{editable-field} widget.
981 @node atoms, composite, generic, Sexp Types
982 @comment node-name, next, previous, up
983 @subsection Atomic Sexp Widgets.
985 The atoms are s-expressions that does not consist of other
986 s-expressions. A string is an atom, while a list is a composite type.
987 You can edit the value of an atom with the following widgets.
989 The syntax for all the atoms are
992 TYPE ::= (NAME [KEYWORD ARGUMENT]... [ VALUE ])
995 The @var{value}, if present, is used to initialize the @code{:value}
996 property and must be an expression of the same type as the widget.
997 I.e. the string widget can only be initialized with a string.
999 All the atom widgets take the same keyword arguments as the @code{editable-field}
1002 @deffn Widget string
1003 Allows you to edit a string in an editable field.
1007 Allows you to edit a file name in an editable field. You you activate
1008 the tag button, you can edit the file name in the mini-buffer with
1014 If this is set to non-nil, only existing file names will be allowed in
1019 @deffn Widget directory
1020 Allows you to edit a directory name in an editable field.
1021 Similar to the @code{file} widget.
1024 @deffn Widget symbol
1025 Allows you to edit a lisp symbol in an editable field.
1028 @deffn Widget integer
1029 Allows you to edit an integer in an editable field.
1032 @deffn Widget number
1033 Allows you to edit a number in an editable field.
1036 @deffn Widget boolean
1037 Allows you to edit a boolean. In lisp this means a variable which is
1038 either nil meaning false, or non-nil meaning true.
1042 @node composite, , atoms, Sexp Types
1043 @comment node-name, next, previous, up
1044 @subsection Composite Sexp Widgets.
1046 The syntax for the composite are
1049 TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
1052 Where each @var{component} must be a widget type. Each component widget
1053 will be displayed in the buffer, and be editable to the user.
1056 The value of a @code{cons} widget is a cons-cell where the car is the
1057 value of the first component and the cdr is the value of the second
1058 component. There must be exactly two components.
1062 The value of a @code{lisp} widget is a list containing the value of
1063 each of its component.
1066 @deffn Widget vector
1067 The value of a @code{vector} widget is a vector containing the value of
1068 each of its component.
1071 The above suffice for specifying fixed size lists and vectors. To get
1072 variable length lists and vectors, you can use a @code{choice},
1073 @code{set} or @code{repeat} widgets together with the @code{:inline}
1074 keywords. If any component of a composite widget has the @code{:inline}
1075 keyword set, its value must be a list which will then be spliced into
1076 the composite. For example, to specify a list whose first element must
1077 be a file name, and whose remaining arguments should either by the
1078 symbol @code{t} or two files, you can use the following widget
1085 :value ("foo" "bar")
1089 The value of a widget of this type will either have the form
1090 @samp{(file t)} or @code{(file string string)}.
1092 This concept of inline is probably hard to understand. It was certainly
1093 hard to implement so instead of confuse you more by trying to explain it
1094 here, I'll just suggest you meditate over it for a while.
1096 @deffn Widget choice
1097 Allows you to edit a sexp which may have one of fixed set of types. It
1098 is currently implemented with the @code{choice-menu} basic widget, and
1099 has a similar syntax.
1103 Allows you to specify a type which must be a list whose elements all
1104 belong to given set. The elements of the list is not significant. This
1105 is implemented on top of the @code{checklist} basic widget, and has a
1109 @deffn Widget repeat
1110 Allows you to specify a variable length list whose members are all of
1111 the same type. Implemented on top of the `editable-list' basic widget,
1112 and has a similar syntax.
1115 @node Widget Properties, Defining New Widgets, Sexp Types, Top
1116 @comment node-name, next, previous, up
1119 You can examine or set the value of a widget by using the widget object
1120 that was returned by @code{widget-create}.
1122 @defun widget-value widget
1123 Return the current value contained in @var{widget}.
1124 It is an error to call this function on an uninitialized widget.
1127 @defun widget-value-set widget value
1128 Set the value contained in @var{widget} to @var{value}.
1129 It is an error to call this function with an invalid @var{value}.
1132 @strong{Important:} You @emph{must} call @code{widget-setup} after
1133 modifying the value of a widget before the user is allowed to edit the
1134 widget again. It is enough to call @code{widget-setup} once if you
1135 modify multiple widgets. This is currently only necessary if the widget
1136 contains an editing field, but may be necessary for other widgets in the
1139 If your application needs to associate some information with the widget
1140 objects, for example a reference to the item being edited, it can be
1141 done with @code{widget-put} and @code{widget-get}. The property names
1142 must begin with a @samp{:}.
1144 @defun widget-put widget property value
1145 In @var{widget} set @var{property} to @var{value}.
1146 @var{property} should be a symbol, while @var{value} can be anything.
1149 @defun widget-get widget property
1150 In @var{widget} return the value for @var{property}.
1151 @var{property} should be a symbol, the value is what was last set by
1152 @code{widget-put} for @var{property}.
1155 @defun widget-member widget property
1156 Non-nil if @var{widget} has a value (even nil) for property @var{property}.
1159 Occasionally it can be useful to know which kind of widget you have,
1160 i.e. the name of the widget type you gave when the widget was created.
1162 @defun widget-type widget
1163 Return the name of @var{widget}, a symbol.
1166 @node Defining New Widgets, Widget Wishlist., Widget Properties, Top
1167 @comment node-name, next, previous, up
1168 @section Defining New Widgets
1170 You can define specialized widgets with @code{define-widget}. It allows
1171 you to create a shorthand for more complex widgets, including specifying
1172 component widgets and default new default values for the keyword
1175 @defun widget-define name class doc &rest args
1176 Define a new widget type named @var{name} from @code{class}.
1178 @var{name} and class should both be symbols, @code{class} should be one
1179 of the existing widget types.
1181 The third argument @var{DOC} is a documentation string for the widget.
1183 After the new widget has been defined, the following two calls will
1184 create identical widgets:
1189 (widget-create @var{name})
1194 (apply widget-create @var{class} @var{args})
1200 Using @code{widget-define} does just store the definition of the widget
1201 type in the @code{widget-type} property of @var{name}, which is what
1202 @code{widget-create} uses.
1204 If you just want to specify defaults for keywords with no complex
1205 conversions, you can use @code{identity} as your conversion function.
1207 The following additional keyword arguments are useful when defining new
1210 @item :convert-widget
1211 Function to convert a widget type before creating a widget of that
1212 type. It takes a widget type as an argument, and returns the converted
1213 widget type. When a widget is created, this function is called for the
1214 widget type and all the widgets parent types, most derived first.
1216 @item :value-to-internal
1217 Function to convert the value to the internal format. The function
1218 takes two arguments, a widget and an external value, and returns the
1219 internal value. The function is called on the present @code{:value}
1220 when the widget is created, and on any value set later with
1221 @code{widget-value-set}.
1223 @item :value-to-external
1224 Function to convert the value to the external format. The function
1225 takes two arguments, a widget and an internal value, and returns the
1226 internal value. The function is called on the present @code{:value}
1227 when the widget is created, and on any value set later with
1228 @code{widget-value-set}.
1231 Function to create a widget from scratch. The function takes one
1232 argument, a widget type, and create a widget of that type, insert it in
1233 the buffer, and return a widget object.
1236 Function to delete a widget. The function takes one argument, a widget,
1237 and should remove all traces of the widget from the buffer.
1240 Function to expand the @samp{%v} escape in the format string. It will
1241 be called with the widget as its argument. Should
1242 insert a representation of the widgets value in the buffer.
1245 Should remove the representation of the widgets value from the buffer.
1246 It will be called with the widget as its argument. It doesn't have to
1247 remove the text, but it should release markers and delete nested widgets
1248 if such has been used.
1250 @item :format-handler
1251 Function to handle unknown @samp{%} escapes in the format string. It
1252 will be called with the widget and the escape character as arguments.
1253 You can set this to allow your widget to handle non-standard escapes.
1255 You should end up calling @code{widget-default-format-handler} to handle
1256 unknown escape sequences, which will handle the @samp{%h} and any future
1257 escape sequences, as well as give an error for unknown escapes.
1260 If you want to define a new widget from scratch, use the @code{default}
1263 @deffn Widget default [ keyword argument ]
1264 Widget used as a base for other widgets.
1266 It provides most of the functionality that is referred to as ``by
1267 default'' in this text.
1270 @node Widget Wishlist., , Defining New Widgets, Top
1271 @comment node-name, next, previous, up
1276 It should be possible to add or remove items from a list with @kbd{C-k}
1277 and @kbd{C-o} (suggested by @sc{rms}).
1280 The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
1281 dash (@samp{-}). The dash should be a button that, when activated, ask
1282 whether you want to add or delete an item (@sc{rms} wanted to git rid of
1283 the ugly buttons, the dash is my idea).
1286 Widgets such as @code{file} and @code{symbol} should prompt with completion.
1289 The @code{menu-choice} tag should be prettier, something like the abbreviated
1293 The functions used in many widgets, like
1294 @code{widget-item-convert-widget}, should not have names that are
1295 specific to the first widget where I happended to use them.
1298 Unchecked items in a @code{radio-button-choice} or @code{checklist}
1299 should be grayed out, and the subwidgets should somehow become inactive.
1300 This could perhaps be implemented by binding @code{widget-inactive} to t
1301 when inserting the grayed out subwidget, and let the widget-specify
1302 functions check that variable.
1305 Flag to make @code{widget-move} skip a specified button.
1308 Document `helper' functions for defining new widgets.
1311 Activate the item this is below the mouse when the button is
1312 released, not the item this is below the mouse when the button is
1313 pressed. Dired and grep gets this right. Give feedback if possible.
1316 Use @samp{@@deffn Widget} to document widgets.
1319 Document global keywords in one place.
1321 Document keywords particular to a specific widget in the widget
1324 Document the `default' widget first.
1326 Split, when needed, keywords into those useful for normal
1327 customization, those primarily useful when deriving, and those who
1328 represent runtime information.
1331 Figure out terminology and @sc{api} for the class/type/object/super
1334 Perhaps the correct model is delegation?
1337 Document @code{widget-browse}.
1340 Make indentation work with glyphs and propertional fonts.
1343 Add object and class hierarchies to the browser.