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Doc fixes re alist-get. (Bug#23548)

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* lisp/subr.el (alist-get): Doc fix.
* doc/lispref/lists.texi (Association Lists): Improve alist-get.
; * etc/NEWS: Related edit.
This commit is contained in:
Glenn Morris 2016-06-07 19:59:37 -04:00
parent ba3f206239
commit 1f85b7ca03
3 changed files with 16 additions and 9 deletions
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12
doc/lispref/lists.texi
View file

@ -1556,12 +1556,16 @@ keys may not be symbols:
@end smallexample @end smallexample
@end defun @end defun
@defun alist-get key value &optional default @defun alist-get key value &optional default remove
This function is like @code{assq}, but instead of returning the entire This function is like @code{assq}, but instead of returning the entire
association for @var{key}, @code{(@var{key} . @var{value})}, it association for @var{key}, @code{(@var{key} . @var{value})}, it
returns just the @var{value}. It returns @var{default} if @var{key} returns just the @var{value}. If @var{key} is not found in
is not found in @var{alist}, defaulting to @code{nil} if @var{default} @var{alist} it returns @var{default}.
is omitted.
This is a generalized variable (@pxref{Generalized Variables}) that
can be used to change a value with @code{setf}. When using it to set
a value, optional argument @var{remove} non-nil means to remove
@var{key} from @var{alist} if the new value is @code{eql} to @var{default}.
@end defun @end defun
@defun rassq value alist @defun rassq value alist

3
etc/NEWS
View file

@ -1680,7 +1680,8 @@ codeset is "UTF-8" (as in "en_US.UTF-8"). This is needed because
MS-Windows doesn't support UTF-8 as codeset in its locales. MS-Windows doesn't support UTF-8 as codeset in its locales.
+++ +++
** New function 'alist-get', which is also a valid place (aka lvalue). ** New function 'alist-get', which is a generalized variable
suitable for use with 'setf'.
+++ +++
** New function 'funcall-interactively', which works like 'funcall' ** New function 'funcall-interactively', which works like 'funcall'

10
lisp/subr.el
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@ -598,10 +598,12 @@ Elements of ALIST that are not conses are ignored."
alist) alist)
(defun alist-get (key alist &optional default remove) (defun alist-get (key alist &optional default remove)
"Get the value associated to KEY in ALIST. "Return the value associated with KEY in ALIST, using `assq'.
DEFAULT is the value to return if KEY is not found in ALIST. If KEY is not found in ALIST, return DEFAULT.
REMOVE, if non-nil, means that when setting this element, we should
remove the entry if the new value is `eql' to DEFAULT." This is a generalized variable suitable for use with `setf'.
When using it to set a value, optional argument REMOVE non-nil
means to remove KEY from ALIST if the new value is `eql' to DEFAULT."
(ignore remove) ;;Silence byte-compiler. (ignore remove) ;;Silence byte-compiler.
(let ((x (assq key alist))) (let ((x (assq key alist)))
(if x (cdr x) default))) (if x (cdr x) default)))