Re: [PATCH] alias.c: use git_config_string() to get alias_val

From: Stephan Beyer <s-beyer@gmx.net>
Date: Apr 5, 2008, 17:39 UTC
Message-ID: <20080405173956.GD14565@leksak.fem-net>
In-Reply-To: <200804051819.46904.chriscool@tuxfamily.org>

Hi,

Show 6 quoted lines

> Did you see:
> 
> "(And no, casting the "char **" into a "const char **" is not a good 
> solution either.)"
> 
> in the above page ?

Yes.

Show 5 quoted lines

> > +	if (!prefixcmp(k, "alias.") && !strcmp(k+6, alias_key))
> > +		return git_config_string((const char**)&alias_val, k, v);
> 
> Are you sure this ugly cast to "const char**" is needed ?
> Isn't there a better way to do it ?

Well, because alias_val is not a constant[1], changing
	static char *alias_val;
to
	static const char *alias_val;
is not an option.

The only other way I see[2] atm is a brain-damaged:
--
static int alias_lookup_cb(const char *k, const char *v)
{
	if (!prefixcmp(k, "alias.") && !strcmp(k+6, alias_key)) {
		const char *tmp;
		int ret = git_config_string(&tmp, k, v);
		alias_val = xstrdup(tmp);
		/* actually, tmp should be free()'d. */
		return ret;
	}
	return 0;
}
--
But instead of doing that, the original should be kept, because it is
better in code beauty, performance and memory usage. ;-)

So I thought the casting is ugly, but it does no harm. I hope ;) (Yes, a cast from const char ** to char ** is, indeed, dangerous.)

But if I miss an obvious point, please tell me :)

Regards,
 Stephan

Footnotes:
 [1] It is no constant because it is returned by alias_lookup(),
     and thus could be changed by further instructions.
 [2] ...between the many ways that result in compiler warnings ;-)

-- 
Stephan Beyer <s-beyer@gmx.net>, PGP 0x6EDDD207FCC5040F