From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Klaus-Dieter Bauer <bauer.klaus.dieter@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: Can the byte-compiler check whether functions passed by name are defined?
Date: Wed, 31 Jul 2013 13:49:19 -0400 [thread overview]
Message-ID: <jwva9l2pqxy.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <CANtbJLGJhgwpkiGNngNMchUSHnhoyFmRO3ggFosh9Zh4oPSiBQ@mail.gmail.com> (Klaus-Dieter Bauer's message of "Wed, 31 Jul 2013 15:44:39 +0200")
> #' would allow checking for a defined function independent of the function,
> the function is oassed to, true... Would require however to change coding
> practice to using this syntax, with the advantage of preventing warnings
> when people don't want the check but the disadvantage, that the warning is
> also supressed when people just don't care. I guess it would still be the
> best solution, that is backward compatible though.
The two aren't mutually exclusive. I'd welcome a patch that adds the
warning when #' is used.
> (eval-and-compile
> (put 'mapcar 'compiler-macro
> (lambda (&rest form)
This should be (lambda (form &rest args)
Warning from a (compiler) macro is a pain in the rear (because the macro
might be called in difference circumstances and because it's not called
at a good time). But if #' warns, then the compiler-macro can simply
turn 'foo into #'foo and leave the warning to the handle of #'.
> 1. Has to be done, though maybe through a macro, for every higher-order
> function.
Note that macroexp.el already has special handling for the main
higher-order functions (to warn about '(lambda ...)). So it could be
implemented there.
> 3. (warn) doesn't emit warnings to the compilation buffer but to the
> separate *Warnings* buffer, making this code only a prrof-of-concept
> without practical value.
You can try to use macroexp--warn-and-return.
> 4. If the quoted funciton is defined in the same file as the higher-order
> function it is passed to, the definition of the quoted function must be
> both before the first use of the function and inside an (eval-and-compile
> ..) block, which can only be prevented by changes to the compiler code
> anyway.
That's why the patch for #' warnings needs to be directly in bytecomp.el
rather than in compiler macros.
Stefan
next prev parent reply other threads:[~2013-07-31 17:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-29 10:35 Can the byte-compiler check whether functions passed by name are defined? Klaus-Dieter Bauer
2013-07-29 15:21 ` Stefan Monnier
2013-07-31 13:44 ` Klaus-Dieter Bauer
2013-07-31 17:49 ` Stefan Monnier [this message]
2013-07-31 18:01 ` Sebastian Wiesner
2013-08-01 20:31 ` Stefan Monnier
2013-08-04 18:41 ` Klaus-Dieter Bauer
2013-08-04 21:11 ` Stefan Monnier
2013-08-05 8:52 ` Klaus-Dieter Bauer
2013-08-05 14:35 ` Stefan Monnier
2013-08-05 18:17 ` Klaus-Dieter Bauer
2013-08-07 11:27 ` Klaus-Dieter Bauer
2013-08-07 14:41 ` Stefan Monnier
2013-08-07 15:11 ` Klaus-Dieter Bauer
2013-08-07 15:21 ` Stefan Monnier
2013-08-07 17:34 ` Stefan Monnier
2013-08-07 21:11 ` Glenn Morris
2013-08-07 21:59 ` Glenn Morris
2013-08-08 1:25 ` Stefan Monnier
2013-08-08 8:44 ` Klaus-Dieter Bauer
2013-08-08 13:07 ` Stefan Monnier
2013-08-07 19:59 ` Klaus-Dieter Bauer
2013-08-07 21:14 ` Stefan Monnier
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