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From: Philipp Stephani <p.stephani2@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>,
	 Stephen Leake <stephen_leake@stephe-leake.org>
Cc: emacs-devel@gnu.org
Subject: Re: check argument count in defcustom :safe?
Date: Sun, 12 Apr 2015 06:45:04 +0000	[thread overview]
Message-ID: <CAArVCkRUCUMMEHJFae9SJ+_6ngtzAL9s5H6NaQB4-XG6q_6O5g@mail.gmail.com> (raw)
In-Reply-To: <jwv8udyj9sf.fsf-monnier+emacs@gnu.org>

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Stefan Monnier <monnier@iro.umontreal.ca> schrieb am So., 12. Apr. 2015 um
05:48 Uhr:

> The number of arguments passed to a function is something that can be
> easily checked by the function, but checking the number of arguments
> accepted by a function is generally impossible (think of a function like
>
>    (lambda (&rest args)
>      (if (> (length args) (if (halting-p (car args)) 2 3))
>          (signal 'wrong-number-of-arguments 'foo (length args)))
>      ...)
>

But most functions are well-behaved and don't impose additional
restrictions over those expressed in their parameter declaration; in these
cases inspecting the argument list using help-function-arglist should work
well enough.
Agreed that using this as safe predicate is a security hole, the choices
should just be normal symbols that are not used as functions.

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  reply	other threads:[~2015-04-12  6:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-11 15:42 check argument count in defcustom :safe? Stephen Leake
2015-04-12  3:48 ` Stefan Monnier
2015-04-12  6:45   ` Philipp Stephani [this message]
2015-04-12 10:00     ` Artur Malabarba
2015-04-12 11:59     ` Stefan Monnier

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