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From: Daniel Colascione <dan.colascione@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>,
	 Eric Schulte <schulte.eric@gmail.com>,
	emacs-devel@gnu.org
Subject: Re: How to fix Emacs24 compiler warning w/o breaking code for previous versions
Date: Sun, 19 Jun 2011 14:14:32 -0700	[thread overview]
Message-ID: <4DFE66B8.7030402@gmail.com> (raw)
In-Reply-To: <811uytyvgc.fsf@gmail.com>

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On 6/16/11 8:42 PM, Jambunathan K wrote:
> I was hoping that there is an elisp equivalent for C-like
> 
> #if emacs-version > a
>     do this
> #else
>     do that
> #endif
> 

The Common Lisp #+ reader macro provides the facility you want. For example,

    (progn #+some-feature 42)

would read as

    (progn 42)

on systems with some-feature present and

    (progn)

on systems without that feature.

CL also allows arbitrary combinations of and, or, and not calls, e.g,

    #+(or feature1 (not feature2))

#- also exists, and is similar, except that the sense of the test is
inverted.

Might this feature be worth adding to Emacs? Of course, it would only
help code written for Emacs 24 and above.


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  parent reply	other threads:[~2011-06-19 21:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-16 17:44 How to fix Emacs24 compiler warning w/o breaking code for previous versions Eric Schulte
2011-06-17  3:10 ` Stefan Monnier
2011-06-17  3:42   ` Jambunathan K
2011-06-17  6:34     ` Stephen J. Turnbull
2011-06-17  7:17       ` Eli Zaretskii
2011-06-19 21:14     ` Daniel Colascione [this message]
2011-06-20  7:53     ` David Kastrup
2011-06-17  4:45   ` Eric Schulte
2011-06-17  7:19 ` David Engster

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