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From: Andreas Schwab <schwab@suse.de>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
	Emacs Development <emacs-devel@gnu.org>
Subject: Re: Understanding macroexp.el
Date: Wed, 18 Nov 2015 12:37:00 +0100	[thread overview]
Message-ID: <mvmr3jnr12b.fsf@hawking.suse.de> (raw)
In-Reply-To: <87h9kjd2dl.fsf@web.de> (Michael Heerdegen's message of "Wed, 18 Nov 2015 11:32:22 +0100")

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Here is an example where it matters:
>
> (defmacro test (exp)
>   (macroexp-let2 nil res exp
>     `(progn
>        (f ,res)
>        (g ,res))))
>
> (note that the `progn' is mandatory here.)  Without the patch:
>
> (macroexpand '(test (+ 1 2)))
> ==>
> (let*
>     ((#:res #1=(+ 1 2)))
>   (progn
>     (f #1#)
>     (g #1#)))
>
>
> After patch:
>
> (macroexpand '(test (+ 1 2)))
> ==>
> (let*
>     ((#:res #1=(+ 1 2)))
>   (f #1#)
>   (g #1#))

For byte-compiled code there should be no difference between the two
expansions.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."



  reply	other threads:[~2015-11-18 11:37 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-18 10:32 Understanding macroexp.el Michael Heerdegen
2015-11-18 11:37 ` Andreas Schwab [this message]
2015-11-18 12:03   ` Michael Heerdegen
2015-11-18 13:36     ` Stefan Monnier
2015-11-18 13:40 ` Stefan Monnier

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