default Widgetitem Widgetlink Widgeturl-link Widgetinfo-link Widgetfunction-link Widgetvariable-link Widgetface-link Widgetfile-link Widgetemacs-library-link Widgetemacs-commentary-link Widgetpush-button Widgeteditable-field Widgettext Widgetmenu-choice Widgetradio-button-choice Widgetchoice-item Widgettoggle Widgetradio-button-toggle Widgetcheckbox Widgetchecklist Widgeteditable-list Widgetgroup Widgetdocumentation-string WidgetNext: Introduction [Contents][Index]
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Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual”, and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License”.
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Next: User Interface, Previous: Top, Up: Top [Contents][Index]
Most graphical user interface toolkits provide a number of standard
user interface controls (sometimes known as “widgets” or “gadgets”).
Emacs doesn’t really support anything like this, except for an
incredibly powerful text “widget”. On the other hand, Emacs does
provide the necessary primitives to implement many other widgets
within a text buffer. The widget package simplifies this task.
The basic widgets are:
linkAreas of text with an associated action. Intended for hypertext links embedded in text.
push-buttonLike link, but intended for stand-alone buttons.
editable-fieldAn editable text field. It can be either variable or fixed length.
menu-choiceAllows the user to choose one of multiple options from a menu, where each option is itself a widget. Only the selected option is visible in the buffer.
radio-button-choiceAllows the user to choose one of multiple options by activating radio buttons. The options are implemented as widgets. All options are visible in the buffer, with the selected one marked as chosen.
itemA simple constant widget intended to be used in the menu-choice and
radio-button-choice widgets.
choice-itemA button item only intended for use in choices. When invoked, the user will be asked to select another option from the choice widget.
toggleA simple ‘on’/‘off’ switch.
checkboxA checkbox (‘[ ]’/‘[X]’).
editable-listCreate an editable list. The user can insert or delete items in the list. Each list item is itself a widget.
Now, of what possible use can support for widgets be in a text editor? I’m glad you asked. The answer is that widgets are useful for implementing forms. A form in Emacs is a buffer where the user is supposed to fill out a number of fields, each of which has a specific meaning. The user is not supposed to change or delete any of the text between the fields. Examples of forms in Emacs are the forms package (of course), the customize buffers, the mail and news compose modes, and the HTML form support in the w3 browser.
The advantages for a programmer of using the widget package to
implement forms are:
Next: Programming Example, Previous: Introduction, Up: Top [Contents][Index]
A form consists of read only text for documentation and some fields, where each field contains two parts, a tag and a value. The tags are used to identify the fields, so the documentation can refer to the ‘foo field’, meaning the field tagged with ‘Foo’. Here is an example form:
Here is some documentation. Name: My Name Choose: This option Address: Some Place In some City Some country. See also _other work_ for more information. Numbers: count to three below [INS] [DEL] One [INS] [DEL] Eh, two? [INS] [DEL] Five! [INS] Select multiple: [X] This [ ] That [X] Thus Select one: (*) One ( ) Another One. ( ) A Final One. [Apply Form] [Reset Form]
The top level widgets in this example are tagged ‘Name’, ‘Choose’, ‘Address’, ‘_other work_’, ‘Numbers’, ‘Select multiple’, ‘Select one’, ‘[Apply Form]’, and ‘[Reset Form]’. There are basically two things the user can do within a form, namely editing the editable text fields and activating the buttons.
In the example, the value for the ‘Name’ is most likely displayed in an editable text field, and so are values for each of the members of the ‘Numbers’ list. All the normal Emacs editing operations are available for editing these fields. The only restriction is that each change you make must be contained within a single editable text field. For example, capitalizing all text from the middle of one field to the middle of another field is prohibited.
Editable text fields are created by the editable-field widget.
The :format keyword is useful for generating the necessary
text; for instance, if you give it a value of "Name: %v ",
the ‘Name: ’ part will provide the necessary separating text
before the field and the trailing space will provide the
separating text after the field. If you don’t include the
:size keyword, the field will extend to the end of the
line, and the terminating newline will provide separation after.
The editing text fields are highlighted with the
widget-field-face face, making them easy to find.
Some portions of the buffer have an associated action, which can
be invoked by a standard key or mouse command. These portions
are called buttons. The default commands for activating a button
are widget-button-press and widget-button-click. The
user typically interacts with the buttons with a key, like RET,
or with the mouse buttons.
There are several different kind of buttons, all of which are present in the example:
When you invoke one of these buttons, you will be asked to choose
between a number of different options. This is how you edit an option
field. Option fields are created by the menu-choice widget. In
the example, ‘Choose’ is an option field tag.
Activating these will insert or delete elements from an editable list.
The list is created by the editable-list widget.
The ‘_other work_’ is an example of an embedded
button. Embedded buttons are not associated with any fields, but can serve
any purpose, such as implementing hypertext references. They are
usually created by the link widget.
Activating one of these will convert it to the other. This is useful
for implementing multiple-choice fields. You can create them with the
checkbox widget.
Only one radio button in a radio-button-choice widget can be
selected at any time. When you invoke one of the unselected radio
buttons, it will be selected and the previous selected radio button will
become unselected.
These are explicit buttons made with the push-button widget. The
main difference from the link widget is that the buttons will be
displayed as GUI buttons when possible.
To make them easier to locate, buttons are emphasized in the buffer
with a distinctive face, like widget-button-face or
widget-mouse-face.
You can use all the normal Emacs commands to move around in a form
buffer, plus you will have these additional commands to navigate from
widget to widget: widget-forward and widget-backward.
Next: Widgets Basics, Previous: User Interface, Up: Top [Contents][Index]
Here is the code to implement the user interface example (see User Interface).
(require 'widget)
(eval-when-compile
(require 'wid-edit))
(defvar widget-example-repeat)
(defun widget-example ()
"Create the widgets from the Widget manual."
(interactive)
(switch-to-buffer "*Widget Example*")
(kill-all-local-variables)
(make-local-variable 'widget-example-repeat)
(let ((inhibit-read-only t))
(erase-buffer))
(remove-overlays)
(widget-insert "Here is some documentation.\n\n")
(widget-create 'editable-field
:size 13
:format "Name: %v " ; Text after the field!
"My Name")
(widget-create 'menu-choice
:tag "Choose"
:value "This"
:help-echo "Choose me, please!"
:notify (lambda (widget &rest ignore)
(message "%s is a good choice!"
(widget-value widget)))
'(item :tag "This option" :value "This")
'(choice-item "That option")
'(editable-field :menu-tag "No option" "Thus option"))
(widget-create 'editable-field
:format "Address: %v"
"Some Place\nIn some City\nSome country.")
(widget-insert "\nSee also ")
(widget-create 'link
:notify (lambda (&rest ignore)
(widget-value-set widget-example-repeat
'("En" "To" "Tre"))
(widget-setup))
"other work")
(widget-insert
" for more information.\n\nNumbers: count to three below\n")
(setq widget-example-repeat
(widget-create 'editable-list
:entry-format "%i %d %v"
:notify
(lambda (widget &rest ignore)
(let ((old (widget-get widget
':example-length))
(new (length (widget-value widget))))
(unless (eq old new)
(widget-put widget ':example-length new)
(message "You can count to %d." new))))
:value '("One" "Eh, two?" "Five!")
'(editable-field :value "three")))
(widget-insert "\n\nSelect multiple:\n\n")
(widget-create 'checkbox t)
(widget-insert " This\n")
(widget-create 'checkbox nil)
(widget-insert " That\n")
(widget-create 'checkbox
:notify (lambda (&rest ignore) (message "Tickle"))
t)
(widget-insert " Thus\n\nSelect one:\n\n")
(widget-create 'radio-button-choice
:value "One"
:notify (lambda (widget &rest ignore)
(message "You selected %s"
(widget-value widget)))
'(item "One") '(item "Another One.")
'(item "A Final One."))
(widget-insert "\n")
(widget-create 'push-button
:notify (lambda (&rest ignore)
(if (= (length
(widget-value widget-example-repeat))
3)
(message "Congratulation!")
(error "Three was the count!")))
"Apply Form")
(widget-insert " ")
(widget-create 'push-button
:notify (lambda (&rest ignore)
(widget-example))
"Reset Form")
(widget-insert "\n")
(use-local-map widget-keymap)
(widget-setup))
Next: Setting Up the Buffer, Previous: Programming Example, Up: Top [Contents][Index]
The Widget Library deals with widgets objects. A widget object has properties whose value may be anything, be it numbers, strings, symbols, functions, etc. Those properties are referred to as keywords and are responsible for the way a widget is represented in a buffer, and control the way a user or a program can interact with it.
The library defines several widget types, and gives you a way to
define new types as well. In addition, widgets can derive from other
types, creating a sort of widget inheritance. In fact, all widgets
defined in the Widget Library share a common parent, the default
widget. In this manual, when we talk about a default behavior, we
usually mean the behavior as defined by this default widget.
See Widget Gallery, for a description of each defined widget.
Defining a new type that derives from a previous one is not mandatory to create widgets that work very different from a specified type. When creating a widget, you can override any default property, including functions, that control the widget. That is, you can specialize a widget on creation, without having to define it as a new type of widget.
In addition to the function for defining a widget, this library provides functions to create widgets, query and change its properties, respond to user events and destroy them. The following sections describe them.
One important property of a widget is its value. All widgets may have a value, which is stored in a so-called internal format. For the rest of Emacs, the widget presents its value in a so-called external format. Both formats can be equal or different, and each widget is responsible for defining how the conversion between each format should happen.
The value property is an important property for almost all widgets,
and perhaps more important for editable-field widgets. This
type of widgets allow the user to edit them via the usual editing
commands in Emacs. They can also be edited programmatically.
Important: You must call widget-setup after
modifying the value of a widget before the user is allowed to edit the
widget again. It is enough to call widget-setup once if you
modify multiple widgets. This is currently only necessary if the widget
contains an editing field, but may be necessary for other widgets in the
future.
If your application needs to associate some information with the widget
objects, for example a reference to the item being edited, it can be
done with the widget-put and widget-get functions. The
property names, as shown, are keywords, so they must begin with a
‘:’.
Next: Working with Widgets, Previous: Widgets Basics, Up: Top [Contents][Index]
To show the widgets in a buffer, you have to create them. Widget creation is actually a two-step process: conversion and creation per se. With simple projects, usually the conversion step isn’t really important, and you only care about widget creation, so feel free to skip the conversion description until you really need to know it.
Widget conversion is the process that involves taking a widget specification and transforming it into a widget object, suitable to be created, queried and manipulated with other widget functions. Widget creation is the process that takes a widget object and actually inserts it in the buffer.
The simplest function to create a widget is widget-create, which
gets a widget specification and returns a widget object.
Create and return a widget of type type, converting it.
type is a symbol that specifies a widget type. keyword may be one of the properties supported by the widget type, and argument specify the value for that property. These keyword arguments can be used to overwrite the keyword arguments that are part of type by default, as well as to provide other properties not present in type by default. args holds additional information for the creation of type and each widget type is responsible for handling that information in a specific way.
The syntax for the type argument is described in Widget Gallery, and in more detail in every widget where it’s relevant.
There are other functions for creating widgets, useful when you work with composite widgets. That is, widgets that are part of other widgets.
Create a widget of type type as a child of parent.
Before creating it, converts type using the keyword arguments
provided in args.
Adds the :indent property, unless it is already present, and
sets it to the sum of the values of: :indent and :offset
from parent and :extra-offset from type.
Returns a widget object, with the property :parent set to
PARENT.
Create a widget of type type as a child of parent.
This function is like widget-create-child-and-convert but it
doesn’t convert type, so it expects an already converted widget.
Create a widget of type type as a child of parent with value value.
This function is like widget-create-child, but it lets you
specify a value for the widget.
Converts value to the internal format, as specified by
type, and stores it into the :value property of type.
That means, value should be in the external format, as
specified by type.
All these creating functions described here use the function stored in
the :create property. So, to modify the creation logic for a
widget, you can provide a different :create function.
When you’re done creating widgets and you’re ready for the user to
interact with the buffer, use the function widget-setup.
Setup the current buffer, so that editable widgets can be edited.
This should be called after creating all the widgets and before allowing the user to edit them.
As mentioned, all these functions return a widget object. That widget object can be queried and manipulated with widget functions that take widgets as arguments, until deleting it with the widgets functions available to delete widgets. Even if you don’t save the returned widget object, you still can interact programmatically with the widget. See Working with Widgets.
Delete the widget widget and remove it from the buffer.
Delete all children and buttons in widget widget.
This function does not delete widget itself, only the widgets
stored in the :children and :buttons properties. It
also sets those properties to nil.
As with the creation mechanism, the function stored in :delete
controls the deletion mechanism for a widget.
Additionally, the library provides a way to make a copy of a widget.
Makes a copy of widget widget and returns it.
It uses the function stored in the :copy property of widget
and returns the widget that that function returns.
As discussed, there is a conversion step when creating a widget. To
do the conversion without actually creating the widget, you can use
the widget-convert function.
Convert type to a widget object, using keyword arguments args.
Returns a widget object, suitable for creation. It calls the function
stored in the :convert-widget property, after putting into the
:args property the arguments that the widget in question needs.
If type has a :value property, either originally or after
doing the conversion, this function converts the value stored in
:value to the internal format, and stores it into :value.
Apart from only creating widgets in the buffer, It’s useful to have
plain text. For inserting text, the recommended way is with the
widget-insert function.
Insert args, either strings or characters, at point.
Uses insert to perform the insertion, passing args as
argument. See Insertion in the Emacs Lisp Reference Manual,
for more information about args.
The resulting text will be read-only.
Next: Widgets and the Buffer, Previous: Setting Up the Buffer, Up: Top [Contents][Index]
This section covers the more important functions needed to query and manipulate widgets in a generic way. Widgets may have additional functions for interacting with them, those are described in the description for each widget. See Widget Gallery.
Non-nil if widget is a widget.
Return the type of widget widget, a symbol.
This function is useful to find out which kind of widget widget represents, i.e., the name of the widget type when the widget was created.
Non-nil if widget widget has a value (even nil) for
property property.
For widget widget, return the value of the property property.
property should be a keyword, and the value is what was last set by
widget-put for property.
For widget widget, set the property property to value. property should be a keyword, while value can be anything.
Return the widget at position pos, or at point if pos is nil.
Return the widget field at position POS, or nil if there is none.
Apply the function stored in property to widget, passing args as additional arguments to the function.
Returns the result of that function call.
Return the current value contained in widget.
Note that the value returned by this function might differ from what’s
stored in the :value property of widget. This is because
this function extracts the current value of widget from the
buffer, taking editions into account.
The value returned is in the external format, after getting it with
the :value-get function.
It is an error to call this function on an uninitialized widget.
Set the value contained in widget to value.
Converts value to the internal format, and then sets it by
applying the :value-set function.
It is an error to call this function with an invalid value, that is, a value that widget cannot represent.
Return the default external value of widget widget.
The default value is the one stored in :value or the result of
applying the :default-get function to the arguments of
widget, as stored in :args. A value of nil is
ignored by default, so in order for a widget to respect nil as
a value, it has to override the :default-get function.
Convert the :type attribute in widget and return its
default value.
Return the value of the first member of :children in
widget.
Return the inline value of the first member of :children in
widget.
The inline value is whatever the function stored in
:value-inline returns.
Create a child widget for widget, of type stored in
:type.
Creates the child widget taking the value from the :value
property and stores the newly created widget in the :children
property of widget.
The value stored in :type should be an unconverted widget
type.
Initializes the :value property of widget from
:args.
Sets :args to nil and returns the modified widget
widget.
Return the value stored in :value for widget widget.
This is different to getting the current value for widget with
widget-value, since that function extracts the value from the
buffer.
Apply the function stored in :action to widget, in
response to event.
It is an error to call this function with an inactive widget.
Tell :parent of widget to handle event.
Optional event is the event that triggered the action.
Check that the first member of :children in widget is valid.
To be valid means that the widget value passes the checks that the
function stored in :validate makes.
Check that all :children in widget are valid.
Returns nil on success, or the first child that isn’t valid.
Return non-nil if VALUE matches the value for the
:type widget.
As with the other type functions, the widget stored in :type
should be an unconverted widget.
Copy the :args value in widget and store them in :args.
Makes the copies by calling widget-copy on each element present
in :args. Returns the modified widget widget.
Convert the :args value in widget and store them in
args.
Returns the modified widget widget.
Next: Widget Gallery, Previous: Working with Widgets, Up: Top [Contents][Index]
This chapter describes commands that are specific to buffers that contain widgets.
Keymap containing useful bindings for buffers containing widgets.
Binds TAB to widget-forward and both S-TAB and
M-TAB to widget-backward. It also binds RET to
widget-button-press and both down-mouse-1 and
down-mouse-2 to widget-button-click.
There’s also a keymap for events that the Widget library doesn’t need to handle.
Keymap used by widget-button-press and widget-button-click
when not on a button. By default this is global-map.
In addition to these two keymaps, each widget might define a keymap of its own, active when events happen at that widget.
The following navigation commands are available:
Move point count buttons or editing fields forward.
Move point count buttons or editing fields backward.
By default, tabbing can put point on an inactive widget. To skip over
inactive widgets when tabbing, set the user option
widget-skip-inactive to a non-nil value.
See Customization.
When editing an editable-field widget, the following commands
are available:
Move point to the end of field or end of line, whichever is first.
Kill to end of field or end of line, whichever is first.
Complete the content of the editable field at point.
Invoke the editable field at point.
The following two commands can execute the action associated with a button widget (e.g., a radio button or checkbox):
Invoke the button at pos, defaulting to point.
Invocation means to run the function stored in the :action
property.
If point is not located on a button, invoke the binding in
widget-global-map (by default the global map).
Invoke the button at the location of the mouse pointer.
If the mouse pointer is located in an editable text field, invoke the
binding in widget-global-map (by default the global map).
In case the mouse-click is on a widget, calls the function stored in
the :mouse-down-action property.
Next: Defining New Widgets, Previous: Widgets and the Buffer, Up: Top [Contents][Index]
All widgets can be created from a type specification. The general syntax of a type specification is:
name ::= (name [keyword argument]... args)
| name
Where name is a widget name, as defined with
define-widget, keyword is the name of a property and
argument is the value for that property, and args are
interpreted in a widget specific way. See Defining New Widgets.
| • Basic Types | ||
| • Sexp Types |
Next: Sexp Types, Up: Widget Gallery [Contents][Index]
| • default | ||
| • item | ||
| • link | ||
| • url-link | ||
| • info-link | ||
| • function-link | ||
| • variable-link | ||
| • face-link | ||
| • file-link | ||
| • emacs-library-link | ||
| • emacs-commentary-link | ||
| • push-button | ||
| • editable-field | ||
| • text | ||
| • menu-choice | ||
| • radio-button-choice | ||
| • choice-item | ||
| • toggle | ||
| • radio-button-toggle | ||
| • checkbox | ||
| • checklist | ||
| • editable-list | ||
| • group | ||
| • documentation-string |
Next: item, Up: Basic Types [Contents][Index]
default WidgetThe most basic widget in the Widget Library is the default widget. It provides the basic behavior for all other widgets, and all its properties are present by default in derived widgets. You’re seldom (if ever) going to effectively create a default widget, but here we describe its properties and behavior, so that we can describe other widgets only by mentioning the properties and behavior those other widgets specialize.
Widget used as a base for other widgets.
It provides most of the functionality that is referred to as “by
default” in this text. If you want to define a new widget from
scratch, use the default widget as its base.
The following keyword arguments apply to all widgets:
:createFunction to create a widget from scratch.
The function takes one argument, a widget type, and creates a widget of that type, inserts it in the buffer, and returns a widget object.
By default, it inserts the widget at point, using the format provided
in the :format property.
:deleteFunction to delete a widget.
The function should take one argument, a widget, and should remove all traces of the widget from the buffer.
The default value is:
Remove widget from the buffer.
Delete all :children and :buttons in widget.
In most cases you should not change this value, but instead use
:value-delete to make any additional cleanup.
:valueThe initial value for widgets of this type.
Typically, a widget represents its value in two formats: external and internal. The external format is the value as the rest of Emacs sees it, and the internal format is a representation that the widget defines and uses in a widget specific way.
Both formats might be the same for certain widgets and might differ
for others, and there is no guarantee about which format the value
stored in the :value property has. However, when creating a
widget or defining a new one (see Defining New Widgets), the
:value should be in the external format.
:value-to-internalFunction to convert the value to the internal format.
The function takes two arguments, a widget and an external value, and
returns the internal value. The function is called on the present
:value when the widget is created, and on any value set later
with widget-value-set.
:value-to-externalFunction to convert the value to the external format.
The function takes two arguments, a widget and an internal value, and returns the value in the external format.
:value-createFunction to expand the ‘%v’ escape in the format string.
It will be called with the widget as its argument and should insert a representation of the widget’s value in the buffer.
:value-deleteA function that should remove the representation of the widget’s value from the buffer.
It will be called with the widget as its argument. It doesn’t have to
remove the text, but it should release markers and delete nested widgets
if these are not listed in :children or :buttons.
By default, it’s a no-op.
:value-getFunction to extract the value of a widget, as it is displayed in the buffer.
:value-setFunction that takes a widget and a value as arguments, and recreates it.
The value must already be in the internal format for widget. By
default, it deletes the widget with the :delete function and
creates it again with the :create function.
:value-inlineFunction that takes a widget and returns its value, inlined.
Inlined means that if the widget is not inline (i.e., its
:inline property is nil), the return value is wrapped in
a list.
:default-getFunction that takes a widget and returns its default value.
By default, it just returns the value stored in :value.
:formatThis string will be inserted in the buffer when you create a widget. The following ‘%’ escapes are available:
The text inside will be marked as a button.
By default, the text will be shown in widget-button-face, and
surrounded by brackets.
The text inside will be displayed with the face specified by
:sample-face.
This will be replaced with the buffer representation of the widget’s value. What this is depends on the widget type.
Insert the string specified by :doc here.
Like ‘%d’, with the following modifications: If the documentation
string is more than one line, it will add a button which will toggle
between showing only the first line, and showing the full text.
Furthermore, if there is no :doc property in the widget, it will
instead examine the :documentation-property property. If it is a
lambda expression, it will be called with the widget’s value as an
argument, and the result will be used as the documentation text.
Insert the string specified by :tag here, or the princ
representation of the value if there is no tag.
Insert a literal ‘%’.
:button-faceFace used to highlight text inside %[ %] in the format.
:button-prefix:button-suffixStrings used as prefix and suffix for widgets that are buttons.
By default, the values are widget-button-prefix and
widget-button-suffix.
Text around %[ %] in the format.
These can be
No text is inserted.
The string is inserted literally.
The value of the symbol is expanded according to this table.
:docThe string inserted by the ‘%d’ escape in the format string.
:tagThe string inserted by the ‘%t’ escape in the format string.
:tag-glyphName of image to use instead of the string specified by :tag on
Emacsen that supports it.
:help-echoSpecifies how to display a message whenever you move to the widget with
either widget-forward or widget-backward or move the mouse
over it (using the standard help-echo mechanism).
The value is either a string to display, or a function of one argument, the widget. If a function, it should return a string to display, or a form that evaluates to such a string.
:follow-linkSpecifies how to interpret a mouse-1 click on the widget. See Defining Clickable Text in the Emacs Lisp Reference Manual.
:indentAn integer indicating the absolute number of spaces to indent children
of this widget. Its value might be nil too, which corresponds
to a value of 0.
The default :create functions and the functions that create the
value per se use this property as a rudimentary layout mechanism for
the widgets.
:offsetAn integer indicating how many extra spaces to add to the widget’s grandchildren compared to this widget.
:extra-offsetAn integer indicating how many extra spaces to add to the widget’s children compared to this widget.
:menu-tagTag used in the menu when the widget is used as an option in a
menu-choice widget.
:menu-tag-getFunction that takes a widget and returns the tag when the widget is
used as an option in a menu-choice widget.
By default, the tag used will be either the :menu-tag or
:tag property if present, or the princ representation of
the :value property if not.
:matchShould be a function called with two arguments, the widget and an
external value, and should return non-nil if the widget can
represent the specified value.
:validateA function which takes a widget as an argument, and returns nil
if the widget’s current value is valid for the widget.
Otherwise, it should return the widget containing the invalid data,
and set that widget’s :error property to a string explaining
the error.
By default, it always returns nil.
:tab-orderSpecify the order in which widgets are traversed with
widget-forward or widget-backward. This is only partially
implemented.
-1 are ignored.
nil,
whichever comes first.
nil
:parentThe parent of a nested widget (e.g., a menu-choice item or an
element of a editable-list widget).
:sibling-argsThis keyword is only used for members of a radio-button-choice or
checklist. The value should be a list of extra keyword
arguments, which will be used when creating the radio-button or
checkbox associated with this item.
:completions-functionFunction that takes a widget and returns completion data for that
widget, like completion-at-point-functions would.
See Completion in the Emacs Lisp Reference Manual. It’s
used by editable-field widgets to provide completions.
By default, it looks into the property :completions, which
should be a completion table. If :completions is nil,
then it calls the function stored either in the :complete or
:complete-function property.
:format-handlerFunction to handle unknown ‘%’ escapes in the format string.
It takes a widget and the character that follows the ‘%’ as arguments. You can set this to allow your widget to handle non-standard escapes in your own specialized widgets.
You should end up calling widget-default-format-handler to handle
unknown escape sequences, which will handle the ‘%h’ and any future
escape sequences, as well as give an error for unknown escapes.
:button-face-getFunction to return the face used to fontify a widget button.
Takes a widget and returns an appropriate face for the widget. By
default, it either returns the face stored in the :button-face
property, or calls the :button-face-get function from the
parent of the widget, if it has one.
:mouse-face-getFunction to return the face used to fontify a widget when the mouse pointer hovers over it.
Takes a widget and returns an appropriate face. By default, it either
returns the face stored in the :mouse-face property, or calls
the :button-face-get function from the parent of the widget, if
it has one.
:copyFunction to deep copy a widget type.
It takes a shallow copy of the widget type as an argument (made by
copy-sequence), and returns a deep copy. The purpose of this
is to avoid having different instances of combined widgets share
nested attributes.
Its value by default is identity.
:activeFunction that takes a widget and returns t if it is active.
A widget might be effectively always active, if its
:always-active property is t.
Widgets can be in two states: active, which means they are modifiable by the user, or inactive, which means they cannot be modified by the user. You can query or set the state with the following code:
;; Examine if widget is active or not.
(if (widget-apply widget :active)
(message "Widget is active.")
(message "Widget is inactive.")
;; Make widget inactive.
(widget-apply widget :deactivate)
;; Make widget active.
(widget-apply widget :activate)
A widget is inactive if it, or any of its ancestors (found by
following the :parent link), have been deactivated. To make sure
a widget is really active, you must therefore activate both it and
all its ancestors.
(while widget (widget-apply widget :activate) (setq widget (widget-get widget :parent)))
You can check if a widget has been made inactive by examining the value
of the :inactive keyword. If this is non-nil, the widget itself
has been deactivated. This is different from using the :active
keyword, in that the latter tells you if the widget or any of
its ancestors have been deactivated. Do not attempt to set the
:inactive keyword directly. Use the :activate
:deactivate functions instead.
:activateFunction that takes a widget and makes it active for user modifications.
:deactivateFunction that takes a widget and makes it inactive for user modifications.
:actionFunction that takes a widget and optionally an event, and handles a user initiated event.
By default, uses the :notify function to notify the widget’s
parent about the event.
:mouse-down-actionFunction that takes a widget and optionally an event, and handles a mouse click on the widget.
By default, it does nothing.
:notifyA function called each time the widget or a nested widget is changed.
The function is called with two or three arguments. The first argument is the widget itself, the second argument is the widget that was changed, and the third argument is the event leading to the change, if any.
By default, it passes the notification to the widget’s parent.
:prompt-valueFunction to prompt for a value in the minibuffer.
The function should take four arguments, a widget, a prompt (a string), a value and a boolean, and should return a value for the widget, entered by the user.
The prompt is the prompt to use. The value is the default value to
use, unless the fourtha argument is non-nil, in which case
there is no default value.
The function should read the value using the method most natural for this widget, and does not have to check that it matches.
Next: link, Previous: default, Up: Basic Types [Contents][Index]
item WidgetSyntax:
type ::= (item [keyword argument]... value)
A useful widget that holds a constant value, and can be included in
other widgets. Its super is the default widget.
As can be seen in the syntax, the item widget is one of the
widget that handles the args argument to widget-create in
a specific way. If present, value is used to initialize the
:value property. When created, it inserts the value as a
string in the buffer.
Example:
(widget-create 'item :tag "Today is" :format "%t: %v\n"
(format-time-string "%d-%m-%Y"))
By default, it has the following properties:
:convert-widgetThe function that allows it to handle value.
:value-createPrints the representation of :value in the buffer.
:value-getReturns the value stored in :value.
:matchA value matches the item widget if it’s equal to its
:value.
:match-inlineInline values match the item widget if :value is a
sublist of values.
:actionThe item widget notifies itself of an event.
:formatBy default, the item widget inserts its tag in the buffer.
Next: url-link, Previous: item, Up: Basic Types [Contents][Index]
link WidgetSyntax:
type ::= (link [keyword argument]... [ value ])
A widget to represent an embedded link. Its super is the item
widget.
The value, if present, is used to initialize the :value
property. The value should be a string, which will be inserted in the
buffer.
Example:
(widget-create 'link
:button-prefix ""
:button-suffix ""
:tag "Mail yourself"
:action #'(lambda (widget &optional _event)
(compose-mail-other-window (widget-value widget)))
user-mail-address)
By default, it has the following properties:
:button-prefixThe value of widget-link-prefix.
:button-suffixThe value of widget-link-suffix.
:keymapA custom keymap for the link widget, so that it can respond to mouse clicks.
:follow-linkThis property allows the link to respect the value of
mouse-1-click-follows-link. See Clickable Text in the Emacs Lisp Reference Manual.
:formatButtonizes the link, to make it clickable.
If you override this property, you should make sure to provide the ‘%[’ and ‘%]’ escape sequences, so that the link is clickable.
By default the link will be shown in brackets.
Next: info-link, Previous: link, Up: Basic Types [Contents][Index]
url-link WidgetSyntax:
type ::= (url-link [keyword argument]... url)
A widget to represent a link to a web page. Its super is the
link widget.
It overrides the :action property to open up the url
specified.
Example:
(widget-create 'url-link
:button-prefix ""
:button-suffix ""
;; Return appropriate face.
:button-face-get (lambda (widget)
(if (widget-get widget :visited)
'link-visited
'link))
:format "%[%t%]"
:tag "Browse this manual"
:action (lambda (widget &optional _event)
(widget-put widget :visited t)
;; Takes care of redrawing the widget.
(widget-value-set widget (widget-value widget))
;; And then call the original function.
(widget-url-link-action widget))
"https://www.gnu.org/software/emacs/manual/html_mono/widget.html")
Next: function-link, Previous: url-link, Up: Basic Types [Contents][Index]
info-link WidgetSyntax:
type ::= (info-link [keyword argument]... address)
A widget to represent a link to an info file. Its super is the
link widget.
It overrides the :action property, to a function to start the
built-in Info reader on address, when invoked.
Example:
(widget-create 'info-link
:button-prefix ""
:button-suffix ""
:tag "Browse this manual"
"(widget) info-link")))
Next: variable-link, Previous: info-link, Up: Basic Types [Contents][Index]
function-link WidgetSyntax:
type ::= (function-link [keyword argument]... function)
A widget to represent a link to an Emacs function. Its super is the
link widget.
It overrides the :action property, to a function to describe
function.
Example:
(widget-create 'function-link
:button-prefix ""
:button-suffix ""
:tag "Describe the function that gets called"
#'widget-function-link-action)
Next: face-link, Previous: function-link, Up: Basic Types [Contents][Index]
variable-link WidgetSyntax:
type ::= (variable-link [keyword argument]... var)
A widget to represent a link to an Emacs variable. Its super is the
link widget.
It overrides the :action property, to a function to describe
var.
Example:
(widget-create 'variable-link
:button-prefix ""
:button-suffix ""
:tag "What setting controls button-prefix?"
'widget-button-prefix)
Next: file-link, Previous: variable-link, Up: Basic Types [Contents][Index]
face-link WidgetSyntax:
type ::= (face-link [keyword argument]... face)
A widget to represent a link to an Emacs face. Its super is the
link widget.
It overrides the :action property, to a function to describe
face.
Example:
(widget-create 'face-link
:button-prefix ""
:button-suffix ""
:tag "Which face is this one?"
'widget-button)
Next: emacs-library-link, Previous: face-link, Up: Basic Types [Contents][Index]
file-link WidgetSyntax:
type ::= (file-link [keyword argument]... file)
A widget to represent a link to a file. Its super is the
link widget.
It overrides the :action property, to a function to find the file
file.
Example:
(let ((elisp-files (directory-files user-emacs-directory t ".el$")))
(dolist (file elisp-files)
(widget-create 'file-link
:button-prefix ""
:button-suffix ""
file)
(widget-insert "\n")))
Next: emacs-commentary-link, Previous: file-link, Up: Basic Types [Contents][Index]
emacs-library-link WidgetSyntax:
type ::= (emacs-library-link [keyword argument]... file)
A widget to represent a link to an Emacs Lisp file. Its super is the
link widget.
It overrides the :action property, to a function to find the file
file.
Example:
(widget-create 'emacs-library-link
:button-prefix ""
:button-suffix ""
:tag "Show yourself, Widget Library!"
"wid-edit.el")
Next: push-button, Previous: emacs-library-link, Up: Basic Types [Contents][Index]
emacs-commentary-link WidgetSyntax:
type ::= (emacs-commentary-link [keyword argument]... file)
A widget to represent a link to the Comment section of an Emacs Lisp
file. Its super is the link widget.
It overrides the :action property, to a function to find the file
file and put point in the Comment section.
Example:
(widget-create 'emacs-commentary-link
:button-prefix ""
:button-suffix ""
:tag "Check our good friend Customize"
"cus-edit.el")
Next: editable-field, Previous: emacs-commentary-link, Up: Basic Types [Contents][Index]
push-button WidgetSyntax:
type ::= (push-button [keyword argument]... [ value ])
A widget that acts as a pushable button. Its super is the item
widget.
The value, if present, is used to initialize the :value
property. The value should be a string, which will be inserted in the
buffer.
By default, it has the following properties:
:button-prefixThe empty string.
:button-suffixThe empty string.
:value-createInserts a representation of the “on” and “off” states for the push button.
The representation might be an image, stored in the :tag-glyph
property, or text. If it is text, it might be the value of the
:tag property, or the :value of the widget, surrounded
with widget-push-button-prefix and
widget-push-button-suffix. See Customization.
:formatButtonizes the widget, to make it clickable.
Next: text, Previous: push-button, Up: Basic Types [Contents][Index]
editable-field WidgetSyntax:
type ::= (editable-field [keyword argument]... [ value ])
A widget that can be edited by the user. Its super is the
default widget.
The value, if present, is used to initialize the :value
property. The value should be a string, which will be inserted in the
field. If not present, :value is the empty string.
Warning: In an editable-field widget, the editable
field must not be adjacent to another widget—that won’t work.
You must put some text in between. Either make this text part of
the editable-field widget itself, or insert it with
widget-insert.
This widget either overrides or adds the following properties:
:convert-widgetJust like the item widget, this function allows it to
initialize :value from value.
:keymapKeymap used in the editable field.
The default value is widget-field-keymap, which allows the user
to use all the normal editing commands, even if the buffer’s major
mode suppresses some of them. Pressing RET invokes the function
specified by :action.
:formatBy default, it specifies to insert only the widget’s value.
Warning: In an editable-field widget, the ‘%v’ escape
must be preceded by some other text in the :format string (if
specified).
:sizeThe width of the editable field.
By default the field will reach to the end of the line.
:value-faceFace used for highlighting the editable field.
Default is widget-field-face, see User Interface.
:secretCharacter used to display the value.
You can set this to, e.g., ?* if the field contains a password
or other secret information. By default, this is nil, and the
value is not secret.
:valid-regexpBy default the :validate function will match the content of the
field with the value of this attribute.
The default value is "" which matches everything.
:validateReturns nil if the current value of the widget matches the
:valid-regexp value.
:prompt-internalA function to read a value for widget, used by the
:prompt-value function.
:prompt-historyA variable that holds the history of field minibuffer edits.
:prompt-valueA function that uses the :prompt-internal function and the
:prompt-history value to prompt for a string, and return the
user response in the external format.
:actionWhen invoked, moves point to the next field.
:value-createFunction that takes care of creating the widget, respecting its
:size and :value.
:value-setFunction to use to modify programmatically the current value of the widget.
:value-deleteFunction that removes the widget so it cannot be edited anymore.
:value-getFunction to return the current text in the widget.
It takes an optional argument, no-truncate. If no-truncate is nil, truncates trailing spaces.
:matchFunction that makes the widget match any string value.
Next: menu-choice, Previous: editable-field, Up: Basic Types [Contents][Index]
text WidgetSyntax:
type ::= (text [keyword argument]... [ value ])
A widget just like the editable-field widget, but intended for
multiline text fields. Its super is the editable-field widget.
It overrides the following properties:
:formatBy default, prints a tag and the value.
:keymapThe default is widget-text-keymap, which does not rebind the
RET key.
Next: radio-button-choice, Previous: text, Up: Basic Types [Contents][Index]
menu-choice WidgetSyntax:
type ::= (menu-choice [keyword argument]... type ... )
A widget to represent a menu of options. Its super is the
default widget.
The type argument represents each possible choice. The widget’s value will be that of the chosen type argument.
It either overrides or adds the following properties:
:convert-widgetA function that takes care of converting each possible choice.
:copyA function to copy each possible choice.
:formatBy default, buttonize the tag and show the value.
:voidWidget type used as a fallback when the value does not match any of the specified type arguments.
By default this is an item widget.
:case-foldIf nil don’t ignore case when prompting for a choice through
the minibuffer.
By default, its value is t.
:childrenA list whose CAR is the widget representing the currently chosen type in the buffer.
:choiceThe current chosen type.
:argsThe list of types.
:value-createThe function that inserts the current value for the widget.
It inserts the first choice that matches, as with the :match
function, the value of the widget.
:value-getReturns the value of the first child for the widget (see the
description for :children above).
:value-inlineReturns the inline value of the first child for the widget.
:default-getThe default value for this widget is the default value for the first
choice, in case :value is missing.
This means that if you want a specific default value for the
menu-choice widget, you should either pass a :value
property when creating it, or arrange the choices so that the first
one can hold your desired default value.
:mouse-down-actionA function that takes care of showing a menu, if possible and desired.
:actionA function that takes care of getting a new choice for the widget.
Depending on the number of choices available, it may show a menu or just toggle the choices, or even do nothing at all.
After getting the choice, it recreates the widget and notifies it.
:validateReturns nil if the widget’s value is a valid choice.
:matchThis widget will match any value matching at least one of the specified type arguments.
:match-inlineA function that returns non-nil if the values match the widget,
taking into account the :inline property.
Next: choice-item, Previous: menu-choice, Up: Basic Types [Contents][Index]
radio-button-choice WidgetSyntax:
type ::= (radio-button-choice [keyword argument]... type ... )
A widget to represent a choice from multiple options. Its super is
the default widget.
The component types specify the choices, with one radio button for each. The widget’s value will be that of the chosen type argument.
It overrides the following properties:
:convert-widgetAs other composite widgets, a function that takes care of converting each available choice.
:copyA function to copy each available choice.
:actionA function that checks if any radio button was pressed and activates the pressed one, possibly deactivating an old one. Then, it notifies itself.
:entry-formatThis string will be inserted for each entry in the list. The following ‘%’ escapes are available:
Replace with the buffer representation of the type widget.
Replace with the radio button.
Insert a literal ‘%’.
:formatBy default, it inserts its value.
:button-argsA list of keywords to pass to the radio buttons. Useful for setting, e.g., the ‘:help-echo’ for each button.
:buttonsThe widgets representing the radio buttons.
:childrenThe widgets representing each type.
:choiceThe current chosen type.
:argsThe list of types.
:value-createA function to insert all available choices.
:value-getReturns the value for the chosen widget.
:value-setA function to set the value to one of its available options.
:value-inlineA function that returns the inline value of the child widget.
:offsetBy default, this widget has an offset of 4.
:validateThe widget validates if the current value is valid for one of its children.
:matchThis widget matches any value that matches at least one of the specified type arguments.
:match-inlineLike the :match function, but taking into account inline
values.
You can add extra radio button items to a radio-button-choice
widget after it has been created with the function
widget-radio-add-item.
Add to radio-button-choice widget widget a new radio button
item of type type.
Please note that such items added after the radio-button-choice
widget has been created will not be properly destructed when
you call widget-delete.
Next: toggle, Previous: radio-button-choice, Up: Basic Types [Contents][Index]
choice-item WidgetSyntax:
item ::= (choice-item [keyword argument]... value)
A widget to represent a choice in a menu-choice widget. Its
super is the item widget.
The value, if present, is used to initialize the :value
property.
It overrides the following properties:
:actionActivating the button of a choice-item is equivalent to
activating the parent widget.
:formatBy default, it buttonizes the tag (i.e., its value) and adds a newline character at the end of the widget.
Next: radio-button-toggle, Previous: choice-item, Up: Basic Types [Contents][Index]
toggle WidgetSyntax:
type ::= (toggle [keyword argument]...)
A widget that can toggle between two states. Its super is the
item widget.
The widget has two possible states, ‘on’ and ‘off’, which
correspond to a t or nil value, respectively.
Example:
(widget-insert "Press the button to activate/deactivate the field: ")
(widget-create 'toggle
:notify (lambda (widget &rest _ignored)
(widget-apply widget-example-field
(if (widget-value widget)
:activate
:deactivate))))
(widget-insert "\n")
(setq widget-example-field
(widget-create 'editable-field
:deactivate (lambda (widget)
(widget-specify-inactive
widget
(widget-field-start widget)
(widget-get widget :to)))))
(widget-apply widget-example-field :deactivate)))
It either overrides or adds the following properties:
:formatBy default, it buttonizes the value and adds a newline at the end of the widget.
:onA string representing the ‘on’ state. By default the string ‘on’.
:offA string representing the ‘off’ state. By default the string ‘off’.
:on-glyphName of a glyph to be used instead of the ‘:on’ text string, on emacsen that supports this.
:off-glyphName of a glyph to be used instead of the ‘:off’ text string, on emacsen that supports this.
:value-createA function for creating the widget’s value, according to its ‘:on’ or ‘:off’ state.
:actionFunction to toggle the state of the widget. After toggling, it notifies itself.
:matchThis widget matches anything.
Next: checkbox, Previous: toggle, Up: Basic Types [Contents][Index]
radio-button-toggle WidgetSyntax:
type ::= (radio-button-toggle [keyword argument]...)
A toggle to use in the radio widget.
It overrides the following properties:
:button-prefixThe empty string.
:button-suffixThe empty string.
:onThe string “(*)”, to represent the ‘on’ state.
:offThe string “( )”, to represent the ‘off’ state.
:on-glyphThe name of an image to represent the ‘on’ state.
:off-glpyhThe name of an image to represent the ‘off’ state.
:formatBy default, it buttonizes its value.
:notifyA function to notify its parent.
Next: checklist, Previous: radio-button-toggle, Up: Basic Types [Contents][Index]
checkbox WidgetSyntax:
type ::= (checkbox [keyword argument]...)
A widget to represent a toggle widget, with a checkbox. Its super is
the toggle widget.
This widget has two possible states, ‘selected’ and
‘unselected’, which corresponds to a t or nil
value, respectively.
It either overrides or adds the following properties:
:button-prefixThe empty string.
:button-suffixThe empty string.
:formatBy default, buttonizes the value.
:onBy default, the string “[X]”.
:offBy default, the string “[ ]”.
:on-glyphThe name of the image to use when the state is ‘on’.
:off-glyphThe name of the image to use when the state is ‘off’.
:actionA function that toggles the checkbox, notifies the parents and in the ‘on’ state, activates its siblings.
Next: editable-list, Previous: checkbox, Up: Basic Types [Contents][Index]
checklist WidgetSyntax:
type ::= (checklist [keyword argument]... type ... )
A widget to represent a multiplice choice. Its super is the
default widget.
The type arguments represent each checklist item. The widget’s value will be a list containing the values of all checked type arguments.
Example:
(widget-create 'checklist
:notify (lambda (widget child &optional _event)
(funcall
(widget-value (widget-get-sibling child))
'toggle))
:value (list 'tool-bar-mode 'menu-bar-mode)
'(item :tag "Tool-bar" tool-bar-mode)
'(item :tag "Menu-bar" menu-bar-mode))))
It either overrides or adds the following properties:
:convert-widgetAs other composite widgets, a function that takes care of converting each checklist item.
:copyA function to copy each checklist item.
:formatBy default, it inserts its value.
:entry-formatThis string will be inserted for each entry in the list. The following ‘%’ escapes are available:
Replaced with the buffer representation of the type widget.
Replace with the checkbox.
Insert a literal ‘%’.
:button-argsA list of keywords to pass to the checkboxes. Useful for setting, e.g., the ‘:help-echo’ for each checkbox.
:buttonsThe widgets representing the checkboxes.
:childrenThe widgets representing each type.
:argsThe list of types.
:value-createThe function that takes care of inserting all values.
:value-getA function that returns all values of selected items.
:validateA function that ensures all selected children are valid.
:matchThe checklist widget will match a list whose elements all match at least one of the specified type arguments.
:match-inlineLike the :match function, but taking into account the
:inline property.
:greedyUsually a checklist will only match if the items are in the exact
sequence given in the specification. By setting :greedy to
non-nil, it will allow the items to come in any sequence.
However, if you extract the value they will be in the sequence given
in the checklist, i.e., the original sequence is forgotten.
Next: group, Previous: checklist, Up: Basic Types [Contents][Index]
editable-list WidgetSyntax:
type ::= (editable-list [keyword argument]... type)
A widget that can hold a variable list of widgets of the same type,
represented by type. Its super is the default widget.
It either overrides or adds the following properties:
:convert-widgetAs other composite widgets, a function that takes care of converting each type in type.
:copyA function to copy the types given in type.
:entry-formatThis string will be inserted for each entry in the list. The following ‘%’ escapes are available:
This will be replaced with the buffer representation of the type widget.
Insert the [INS] button, a widget of type insert-button.
Insert the [DEL] button, a widget of type delete-button.
Insert a literal ‘%’.
:insert-button-argsA list of keyword arguments to pass to the insert buttons.
:delete-button-argsA list of keyword arguments to pass to the delete buttons.
:append-button-argsA list of keyword arguments to pass to the trailing insert button.
:buttonsThe widgets representing the insert and delete buttons.
:formatBy default, insert its value and at the and adds an insert button.
This is useful so that new elements can be added to the list upon user request.
:format-handlerA function that recognize the escape for inserting an insert button.
:offsetBy default, this widget has an offset of 12.
:childrenThe widgets representing the elements of the list.
:argsList whose CAR is the type of the list elements.
:insert-beforeFunction to insert a new widget as a child of the editable-list
widget.
This function inserts a recently deleted child, if there is one. That is useful, so that the user can move elements in a list easily. If there is not a recently deleted child, it inserts a child with its default value.
:delete-atFunction to delete a child from the widget, and store it into the
:last-deleted list, so that it can be reinserted when the
:insert-before function executes.
:value-createThe function that takes care of inserting all values.
:value-getFunction that returns a list with the value of the child widgets.
:validateThis widget validates if all children validate.
:matchTo match, the value must be a list and all the list members must match the specified type.
:match-inlineLike the :match function, but taking into account inline
values and widgets.
Next: documentation-string, Previous: editable-list, Up: Basic Types [Contents][Index]
group WidgetSyntax:
type ::= (group [keyword argument]... type...)
A widget to group other widgets. Its super is the default
widget.
Its value is a list, with one member for each type.
It overrides the following properties:
:convert-widgetAs other composite widgets, a function that takes care of converting each widget in type.
:copyA function to copy the types given in type.
:formatBy default, displays a newline character and its value.
:value-createA function to create each of its components.
:value-getThe same function used by the editable-list widget.
:default-getA function that returns a list whose members are the default values of each widget it groups.
:validateThis widget validates if all of its children validate.
:matchThis widget matches a value that matches each of its components.
:match-inlineAs :match, but taking into account widgets and values that are
inline.
Previous: group, Up: Basic Types [Contents][Index]
documentation-string WidgetSyntax:
type ::= (documentation-string [keyword argument]... value)
A widget to represent a documentation string. Its super is the
item widget.
It either overrides or adds the following properties:
:formatBy default, insert its value.
:value-createFunction to insert a documentation string, possibly hiding part of the documentation if its large.
To show or hide the rest of the documentation, uses a
visibility widget.
:actionFunction to toggle showing the documentation upon an event.
:visibility-widgetA symbol, the type of the widget to use for the visibility widget.
This is, by default, the symbol visibility.
Previous: Basic Types, Up: Widget Gallery [Contents][Index]
A number of widgets for editing s-expressions (Lisp types), sexp for short, are also available. These basically fall in several categories described in this section.
| • constants | ||
| • generic | ||
| • atoms | ||
| • composite |
Next: generic, Up: Sexp Types [Contents][Index]
The const widget can contain any Lisp expression, but the user is
prohibited from editing it, which is mainly useful as a component of one
of the composite widgets.
The syntax for the const widget is:
type ::= (const [keyword argument]... [ value ])
Its super is the item widget. The value, if present, is
used to initialize the :value property and can be any
s-expression.
This will display any valid s-expression in an immutable part of the buffer.
It overrides the :prompt-value function, to avoid prompting and
just return the widget’s value.
There are two variations of the const widget, namely
variable-item and function-item. These should contain a
symbol with a variable or function binding, respectively. The major
difference from the const widget is that they will allow the
user to see the variable or function documentation for the symbol.
This is accomplished via using the ‘%h’ format escape, and adding
an appropriate :documentation-property function for each widget.
An immutable symbol that is bound as a variable.
An immutable symbol that is bound as a function.
Next: atoms, Previous: constants, Up: Sexp Types [Contents][Index]
The sexp widget can contain any Lisp expression, and allows the
user to edit it inline in the buffer.
The syntax for the sexp widget is:
type ::= (sexp [keyword argument]... [ value ])
This widget represents an editable field that’s useful to edit any valid s-expression.
The sexp widget takes the same keyword arguments as the
editable-field widget. See editable-field.
Its default value is nil.
A widget to edit Lisp expressions restricted to certain values or
types. Its super is the sexp widget.
It works just like the sexp widget, but it overrides the :match
function to match for certain values. To use this widget, either you
must define a :match function or give a
:match-alternatives property. The :match-alternatives
property holds a list of predicate functions to call when checking if
a given value matches the widget. Each predicate function will be
called with one argument, the value to be matched, and should return
non-nil on success.
As an example, the integer widget overrides
:match-alternatives to (integerp).
Next: composite, Previous: generic, Up: Sexp Types [Contents][Index]
The atoms are s-expressions that do not consist of other s-expressions. For example, a string, a file name, or a symbol are atoms, while a list is a composite type. You can edit the value of an atom with the widgets described in this section.
The syntax for all the atoms is:
type ::= (construct [keyword argument]... [ value ])
The value, if present, is used to initialize the :value
property and must be an expression of the same type as the widget.
That is, for example, the string widget can only be initialized with a
string.
All the atom widgets take the same keyword arguments as the
editable-field widget. See editable-field.
An editable field widget that can represent any Lisp string.
It offers completion via the ispell library and the :complete
property.
An editable field widget that can represent a regular expression.
Overrides the :match and the :validate properties to
check that the value is a valid regexp.
An editable field widget that can represent a character.
The character widget represents some characters (like the newline character) in a special manner, to make it easier for the user to see what’s the content of the character field.
A widget for editing file names.
Keywords:
:completionsOffers file name completion to the user.
:prompt-valueA function to read a file name from the minibuffer.
:must-matchIf this is set to non-nil, only existing file names are allowed
when prompting for a value in the minibuffer.
:matchThe widget matches if the value is a string, and the file whose name
is that string is an existing file, or if :must-match is
nil.
:validateThe widget is valid if its value matches.
A widget for editing directory names.
Its super is the file widget, and it overrides the
:completions property, to offer completions only for
directories.
A widget for editing a Lisp symbol.
Its value by default is nil.
A widget for editing a lambda expression, or a function name, offering
completion. Its super is the restricted-sexp widget.
A widget for editing variable names, offering completion. Its super
is the symbol widget.
A widget for editing integers in an editable field. Its super is the
restricted-sexp widget.
It has a default :value of 0.
A widget for editing non-negative integers. Its super is the
restricted-sexp widget.
It has a default :value of 0.
A widget for editing a floating point number. Its super is the
restricted-sexp widget.
It has a default :value of 0.0.
A widget for editing a number, either floating point or integer. Its
super is the restricted-sexp widget.
It has a default :value of 0.0.
A widget for editing a boolean value. Its super is the toggle
widget.
Its value may be nil, meaning false, or non-nil, meaning
true.
A widget to edit a color name.
In addition, shows a sample that shows the selected color, if any.
A widget useful as the last item in a choice widget, since it
matches any value.
Its super is the sexp widget, and its :value is
other, by default.
A widget that can represent a coding system name, offering
completions. See Coding Systems in the Emacs Lisp Reference
Manual. Its super is the symbol widget.
It has a default value of undecided.
A widget to represent a key sequence.
It uses a special keymap as the :keymap.
Previous: atoms, Up: Sexp Types [Contents][Index]
The syntax for the composite widget construct is:
type ::= (construct [keyword argument]... component...)
where each component must be a widget type. Each component widget will be displayed in the buffer, and will be editable by the user.
A widget to edit cons-cell values. Its super is the group
widget.
The value of a cons widget must be a cons-cell whose CAR
and CDR have two specified types. It uses this syntax:
type ::= (cons [keyword argument]... car-type cdr-type)
A widget to hold a value of one of a fixed set of types. Its super is
the menu-choice widget.
The widget’s syntax is as follows:
type ::= (choice [keyword argument]... type ... )
The value of a choice widget can be anything that matches any of the
types.
This widget only displays the widget that corresponds to the current choice.
A widget to hold a value of one of a fixed set of options. Its super is
the radio-button-choice widget.
A widget to edit a list value. Its super is the group widget.
The value of a list widget must be a list whose element types
match the specified component types:
type ::= (list [keyword argument]... component-type...)
Thus, for example, (list string number) matches lists of two
elements, the first being a string and the second being a number.
A widget to edit a vector value. Its super is the group
widget.
The vector widget is like the list widget but matches
vectors instead of lists. Thus, for example, (vector string
number) matches vectors of two elements, the first being a string and
the second being a number.
The above suffice for specifying fixed size lists and vectors. To get
variable length lists and vectors, you can use a choice,
set, or repeat widget together with the :inline
keyword. If any component of a composite widget has the
:inline keyword set, its value must be a list which will then
be spliced into the composite. For example, to specify a list whose
first element must be a file name, and whose remaining elements should
either be the symbol t or two strings (file names), you can use
the following widget specification:
(list file
(choice (const t)
(list :inline t
:value ("foo" "bar")
string string)))
The value of a widget of this type will either have the form
(file t) or (file string string).
This concept of :inline may be hard to understand. It was
certainly hard to implement, so instead of confusing you more by
trying to explain it here, I’ll just suggest you meditate over it for
a while.
A widget to hold a list of members from a fixed set. Its super is the
checklist widget.
Its value is a list where the elements all belong to a given set. The order of elements of the list is not significant.
Here’s the syntax:
type ::= (set [keyword argument]... permitted-element ... )
Use const to specify each permitted element, like this:
(set (const a) (const b)).
Specifies a list of any number of elements that fit a certain type.
Its super is the editable-list widget.
type ::= (repeat [keyword argument]... type)
A widget to edit property lists. Its super is the list widget.
It recognizes the following properties:
:optionsA given set of recommended key-value values for the plist
widget. Each option shows up as a checklist item.
:key-typeThe widget type to use for the plist keys. By default, it uses the
symbol widget.
:value-typeThe widget type to use for the plist values. By default, it uses the
sexp widget.
A widget to edit association lists. Its super is the list
widget.
It recognizes the same properties that the plist widget, with
the difference that the :key-type uses by default a sexp
widget.
Most composite widgets do not allow for recursion. That is, none of
the contained widgets may be of the same type that is currently being
defined. To allow for this kind of widgets, there’s the lazy
widget.
A base widget for recursive data structures. Its super is the
default widget.
When instantiated, it contains a single inferior widget of the widget
type specified in the :type property. Its value is the same as
the value of this inferior widget.
Next: Inspecting Widgets, Previous: Widget Gallery, Up: Top [Contents][Index]
You can define specialized widgets with define-widget. It allows
you to create a shorthand for more complex widgets, including specifying
component widgets and new default values for the keyword arguments.
Define a new widget type named name that derives from class.
name and class should both be symbols, and class should be one of the existing widget types.
The third argument doc is a documentation string for the widget.
args should be key-value pairs, overriding keyword values of class, or adding new recognized keywords for name.
Usually, you’ll want to derive from an existing widget type, like the
editable-field widget, or the default widget, but it’s
also possible to derive from nothing, by passing a value of nil
as class. Note that if you do this, you’re entirely responsible
for defining a whole new default behavior for your widgets.
After using this function, the following two calls will create identical widgets:
(widget-create name)
(apply widget-create class args)
Using define-widget just stores the definition of the widget type
in the widget-type property of name, which is what
widget-create uses.
If you only want to specify defaults for keywords with no complex
conversions, you can use identity as your conversion function.
When defining new widgets, the :convert-widget property might
be useful:
:convert-widgetFunction to convert a widget type before creating a widget of that type.
It takes a widget type as an argument, and returns the converted widget type. When a widget is created, this function is called for the widget type and all the widget’s parent types, most derived first.
The predefined functions widget-types-convert-widget and
widget-value-convert-widget can be used here.
Example:
(defvar widget-ranged-integer-map
(let ((map (copy-keymap widget-keymap)))
(define-key map [up] #'widget-ranged-integer-increase)
(define-key map [down] #'widget-ranged-integer-decrease)
map))
(define-widget 'ranged-integer 'integer "A ranged integer widget." :min-value most-negative-fixnum :max-value most-positive-fixnum :keymap widget-ranged-integer-map)
(defun widget-ranged-integer-change (widget how)
"Change the value of the ranged-integer WIDGET, according to HOW."
(let* ((value (widget-value widget))
(newval (cond
((eq how 'up)
(if (< (1+ value) (widget-get widget :max-value))
(1+ value)
(widget-get widget :max-value)))
((eq how 'down)
(if (> (1- value) (widget-get widget :min-value))
(1- value)
(widget-get widget :min-value)))
(t (error "HOW has a bad value"))))
(inhibit-read-only t))
(widget-value-set widget newval)))
(defun widget-ranged-integer-increase (widget) "Increase the value of the ranged-integer WIDGET." (interactive (list (widget-at))) (widget-ranged-integer-change widget 'up))
(defun widget-ranged-integer-decrease (widget) "Decrease the value of the ranged-integer WIDGET." (interactive (list (widget-at))) (widget-ranged-integer-change widget 'down))
Next: Widget Minor Mode, Previous: Defining New Widgets, Up: Top [Contents][Index]
There is a separate package to browse widgets, in ‘wid-browse.el’. This is intended to help programmers who want to examine the content of a widget. The browser shows the value of each keyword, but uses links for certain keywords such as ‘:parent’, which avoids printing cyclic structures.
Create a widget browser for widget.
When called interactively, prompt for widget.
Create a widget browser for widget and show it in another window.
When called interactively, prompt for widget.
Create a widget browser for the widget at pos.
When called interactively, use the position of point.
In addition, there’s a function to describe the widget at point.
Describe the widget at point.
When called from Lisp, widget-or-pos might be the widget to
describe or a buffer position where a widget is present. If
widget-or-pos is nil, the widget to describe is the
widget at point.
This command sets up a help buffer for providing information about the
widget, mainly its :action and :mouse-down-action
functions, and provides links to describe it in more detail using the
widget-browse commands described above.
Next: Utilities, Previous: Inspecting Widgets, Up: Top [Contents][Index]
There is a minor mode for manipulating widgets in major modes that don’t provide any support for widgets themselves. This is mostly intended to be useful for programmers doing experiments.
Toggle minor mode for traversing widgets. With arg, turn widget mode on if and only if arg is positive.
Keymap used in widget-minor-mode.
Next: Customization, Previous: Widget Minor Mode, Up: Top [Contents][Index]
Here we describe some utility functions that don’t really have a place earlier in this manual.
Prompt for a value matching widget, using prompt.
The current value is assumed to be value, unless unbound is
non-nil.
Converts widget before prompting, and for prompting it uses the
:prompt-value function. This function returns the user
“answer”, and it’s an error if that answer doesn’t match the widget,
as with the :match function.
If the answer matches the widget, returns the answer.
Get the item which widget should toggle. This is only meaningful for radio buttons or checkboxes in a list.
Prompt the user to choose an item from a list of options.
title is the name of the list of options. items should be
a menu, with its items in the simple format or in the extended format.
See Defining Menus in the Emacs Lisp Reference
Manual. Independently of the format, you don’t have to provide a
title for the menu, just pass the desired title in title. The
optional event is an input event. If event is a mouse
event and the number of elements in items is less than the user
option widget-menu-max-size, then widget-choose uses a
popup menu to prompt the user. Otherwise, widget-choose uses
the minibuffer.
When items is a keymap menu, the returned value is the symbol in
the key vector, as in the argument of define-key
(see Changing Key Bindings in the Emacs Lisp Reference
Manual). When items is a list whose selectable items are of
the form (name . value) (i.e., the simplified format),
then the return value is the value of the chosen element.
Create a graphical button from image, an image or a file name sans extension.
If image is a file name, the file should be in
widget-image-directory, or in a place where find-image
will find it.
As part of widget, insert the text tag or, if supported, the image image.
image should be as described in widget-image-find.
Display help-echo text for the widget at pos.
Uses the value of :help-echo. If it is a function, it calls it
to get a string. Otherwise, it evals it.
Next: Widget Wishlist, Previous: Utilities, Up: Top [Contents][Index]
This chapter is about the customization options for the Widget library, for the end user.
Face used for documentation text.
Face used for editable fields.
Face used for buttons.
Face used for pressed buttons.
Face used for inactive widgets.
Face used for unselected widgets. This face is also used on the text labels of radio-button and checkbox widgets.
The default value inherits from the widget-inactive face. If you
want to visually distinguish the labels of unselected active
radio-button or checkbox widgets from the labels of unselected inactive
widgets, customize this face to a non-default value.
Face used for highlighting a button when the mouse pointer moves across it.
The default value is highlight.
Directory where Widget should look for images.
Widget will look here for a file with the same name as specified for the image, with either a .xpm (if supported) or .xbm extension.
If non-nil, allow images to appear on displays where they are supported.
An alist to convert symbols from image formats to file name suffixes.
Each element is a cons cell (format . suffix), where format is a symbol that represents an image format and suffix is its correspondent suffix.
String to prefix buttons.
String to suffix buttons.
String to prefix push buttons.
String to suffix push buttons.
String to prefix links.
String to suffix links.
If non-nil, toggle when there are just two options.
By default, its value is nil.
If non-nil, skip over inactive widgets when using TAB
(widget-forward) or S-TAB (widget-backward,
also bound to M-TAB) to navigate between widgets.
By default, its value is nil and tabbing does not skip over
inactive widgets.
If non-nil, add hyperlinks to documentation strings.
A regexp that matches potential links in documentation strings. The link itself should match to the first group.
A predicate function to test if a string is useful as a link. The
function is called with one argument, a string, and should return
non-nil if there should be a link for that string.
By default, the value is intern-soft.
A symbol that represents a widget type to use for links in documentation strings.
By default, the value is documentation-link.
Maximum size for a popup menu. By default, its value is 40.
If a function ask you to choose from a menu that is larger than this value, it will use the minibuffer.
Largest number of items for which it works to choose one with a character.
For a larger number, use the minibuffer.
Whether to use the minibuffer to ask for a choice.
If nil, the default, read a single character.
Next: GNU Free Documentation License, Previous: Customization, Up: Top [Contents][Index]
menu-choice tag should be prettier, something like the abbreviated
menus in Open Look.
:tab-order.
widget widget for editing widget specifications.
TeX-printer-list for an explanation.
widget-prompt-value should give type specific help.
mailto widget.
Next: Index, Previous: Widget Wishlist, Up: Top [Contents][Index]
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If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.
You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.
The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See https://www.gnu.org/licenses/.
Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document.
“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or in part, as part of another Document.
An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing.
To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (C) year your name. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this:
with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
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This is an alphabetical listing of all concepts, functions, commands, variables, and widgets described in this manual.
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