A number of widgets for editing s-expressions (lisp types) are also available. These basically fall in the following categories.
The const
widget can contain any lisp expression, but the user is
prohibited from editing edit 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 ])
The value, if present, is used to initialize the :value
property and can be any s-expression.
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. The major difference from
the const
widget is that they will allow the user to see the
variable or function documentation for the symbol.
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 ])
The sexp
widget takes the same keyword arguments as the
editable-field
widget.
The atoms are s-expressions that does not consist of other s-expressions. A string is an atom, while a list is a composite type. You can edit the value of an atom with the following widgets.
The syntax for all the atoms are
TYPE ::= (NAME [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.
I.e. the string widget can only be initialized with a string.
All the atom widgets take the same keyword arguments as the
editable-field
widget.
Keywords:
:must-match
file
widget.
The syntax for the composite are
TYPE ::= (NAME [KEYWORD ARGUMENT]... COMPONENT...)
Where each component must be a widget type. Each component widget will be displayed in the buffer, and be editable to the user.
cons
widget is a cons-cell where the car is the
value of the first component and the cdr is the value of the second
component. There must be exactly two components.
list
widget is a list containing the value of
each of its component.
vector
widget is a vector containing the value of
each of its component.
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
widgets together with the :inline
keywords. 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 arguments should either by the
symbol t
or two files, 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 is probably hard to understand. It was certainly hard to implement so instead of confuse you more by trying to explain it here, I'll just suggest you meditate over it for a while.
choice-menu
basic widget, and
has a similar syntax.
checklist
basic widget, and has a
similar syntax.
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