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Re: emacs' turn: remove useless if-before-free tests


From: YAMAMOTO Mitsuharu
Subject: Re: emacs' turn: remove useless if-before-free tests
Date: Mon, 02 Jun 2008 11:34:23 +0900
User-agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (Shij┼Ź) APEL/10.6 Emacs/23.0.50 (sparc-sun-solaris2.8) MULE/5.0 (SAKAKI)

>>>>> On Mon, 02 Jun 2008 11:05:55 +0900, Miles Bader <address@hidden> said:

>> I guess the acceptance of NULL for `free' in POSIX is the
>> reflection of the fact that `malloc' may return NULL.  If so, we
>> could take a different policy for `xfree', i.e., abort if NULL,
>> because `xmalloc' may not return NULL unlike malloc.  This may help
>> us detect the behavior that is different from programmer's
>> intention.

> xmalloc can return NULL.

IIUC, only when the SIZE argument is 0.  I think many programmers have
never cared about the NULL-check of the return value of xmalloc where
they are sure that its argument is positive.  Also we could make
xmalloc to return a non-NULL value for the case SIZE==0.

> I think xmalloc and xfree should act as much like posix malloc/free
> as possible, modulo the error-handling behavior of xmalloc.  That
> will be the least surprising to programmers using them.  Indeed, we
> can make them act like the posix function even on systems whose
> native malloc is less so.

That would be one policy.  What I said is just another possible policy
that could make use of the explicit distinction between `if (p) xfree
(p)' and `xfree (p)' programmers have been made rather than losing
such information just for cleanup.

                                     YAMAMOTO Mitsuharu
                                address@hidden




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