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j8takagi/update-or-add-alist.el

Last active May 27, 2017 13:54
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A Emacs Lisp utilitiy for managing association list (alist), such as default-frame-alist. If key in ALIST, update VALUE of the key. Unless, cons cell (KEY . VALUE) is added
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update-or-add-alist.el
(defun update-or-add-alist (alist-var key value)
"If KEY in ALIST, update VALUE of the KEY.
Unless, cons cell (KEY . VALUE) is added."
(interactive)
(let (aconscell (alist (symbol-value alist-var)))
(if (setq aconscell (assoc key alist))
(unless (equal (cdr aconscell) value)
(setf (cdr aconscell) value))
(set alist-var (push (cons key value) alist)))
alist))
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