From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: Alternative approach to the git config NULL value checking patches..
Date: Sun, 10 Feb 2008 16:40:46 -0800
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To: Linus Torvalds <torvalds@linux-foundation.org>
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Linus Torvalds <torvalds@linux-foundation.org> writes:

> And here's an example of this kind of effect. I'm not actually suggesting 
> you apply this patch, but tell me it isn't simpler done this way?

Yes, that is a good example of simplification.

> So this is where it *does* make a difference whether we use NULL or 
> config_bool, and where config_bool is simply better: it allows a config 
> routine to simply never care..

But that applies only to "originally bool but now has additional
states" kind of variables.

For a variable that is never about boolean, if the original code
said:

	if (!strcmp(var, "section.variable"))
        	foo = xstrdup(value);

it is wrong (would strdup NULL), and the correct fix would be:

	if (!strcmp(var, "section.variable")) {
		if (!value)
			die("missing value for '%s'", var);
        	foo = xstrdup(value);
	}

It does not make much of a difference if that "if (!value)"
becomes "if (value == config_true)".  If you omit that check, as
your "user.name" example shows, foo may get an empty string or a
string "true", neither of which is what the user intended to
say.