From: Emanuel Berg <embe8573@student.uu.se>
To: help-gnu-emacs@gnu.org
Subject: Re: How to shadow a function temporarily? (flet and cl-flet)
Date: Sun, 26 Jan 2014 19:32:34 +0100 [thread overview]
Message-ID: <87y522wq3o.fsf@nl106-137-194.student.uu.se> (raw)
In-Reply-To: mailman.12843.1390745495.10748.help-gnu-emacs@gnu.org
Alex Kost <alezost@gmail.com> writes:
> 1. The main question is: how can I override a
> function with another compatible function (with the
> same args) temporarily?
;;;; dynamic (Emacs wide)
;; first store the correct functions so we have them
;; (note: "subr" as in "subroutine", not "subtract")
(setq addition-fun (symbol-function '+)) ; #<subr +>
(setq subtraction-fun (symbol-function '-)) ; #<subr ->
;; change + to do subtraction
(fset '+ subtraction-fun)
(+ 1 2 3) ; -4
;; revert
(fset '+ addition-fun)
(+ 1 2 3) ; 6
;;; lexical
(cl-labels ((+ (&rest args) (apply '- args)))
(+ 1 2 3) ) ; -4
(+ 1 2 3) ; still 6
--
underground experts united:
http://user.it.uu.se/~embe8573
next prev parent reply other threads:[~2014-01-26 18:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.12843.1390745495.10748.help-gnu-emacs@gnu.org>
2014-01-26 16:22 ` How to shadow a function temporarily? (flet and cl-flet) Emanuel Berg
2014-01-26 19:25 ` Alex Kost
2014-01-26 18:32 ` Emanuel Berg [this message]
2014-01-26 19:38 ` Alex Kost
2014-01-26 19:36 ` Barry Margolin
2014-01-26 19:45 ` Michael Heerdegen
2014-01-26 22:07 ` Alex Kost
2014-01-26 14:11 Alex Kost
2014-01-26 14:50 ` Stefan Monnier
2014-01-26 19:24 ` Alex Kost
2014-01-26 22:08 ` Stefan Monnier
2014-01-27 5:57 ` Alex Kost
2014-01-27 13:40 ` Stefan Monnier
2014-01-27 14:59 ` Alex Kost
2014-01-26 19:03 ` Marcin Borkowski
2014-01-26 19:31 ` Alex Kost
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