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From: Junio C Hamano <gitster@pobox•com>
To: Jeremiah Mahler <jmmahler@gmail•com>
Cc: Jeff King <peff@peff•net>, git@vger•kernel.org
Subject: Re: [PATCH v2] format-patch --signature-file <file>
Date: Mon, 19 May 2014 09:54:33 -0700	[thread overview]
Message-ID: <xmqqd2f93e0m.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20140517153943.GB31912@hudson.localdomain> (Jeremiah Mahler's message of "Sat, 17 May 2014 08:39:43 -0700")

Jeremiah Mahler <jmmahler@gmail•com> writes:

> On Sat, May 17, 2014 at 06:00:14AM -0400, Jeff King wrote:
>> 
>> If you wanted to know whether it was set, I guess you'd have to compare
>> it to the default, like:
>> 
>>   if (signature_file) {
>> 	if (signature && signature != git_version_string)
>> 		die("you cannot specify both a signature and a signature-file");
>> 	... read signature file ...
>>   }
>> 
>
> That works until someone changes the default value.
> But if they did that then some tests should fail.
>
> I like the address comparision which avoids a string comparision.

Well, "avoids" is not quite a correct phrasing, because !strcmp()
would be wrong there.  You cannot tell "the user did not set
anything and the variable stayed as the default" and "the user
explicitly gave us a string but it happened to be the same as the
default" apart with !strcmp().  Address comparison is not just
"avoids" but is the right thing to do in this case.

>> though it's a bit ugly that this code has to know what the default is.

Avoiding that is easy with an indirection, no?  Something like this
at the top:

  static const char *the_default_signature = git_version_string;
  static const char *signature = the_default_signature;

and comparing to see if signature points at the same address as
the_default_signature would give you what you want, I think.

  reply	other threads:[~2014-05-19 16:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-16  1:31 [PATCH v2] format-patch --signature-file <file> Jeremiah Mahler
2014-05-16  1:31 ` Jeremiah Mahler
2014-05-16  8:14   ` Jeff King
2014-05-17  7:25     ` Jeremiah Mahler
2014-05-17  7:42       ` Jeff King
2014-05-17  8:59         ` Jeremiah Mahler
2014-05-17 10:00           ` Jeff King
2014-05-17 15:39             ` Jeremiah Mahler
2014-05-19 16:54               ` Junio C Hamano [this message]
2014-05-20  5:46                 ` Jeremiah Mahler
2014-05-20  6:21                   ` Jeff King
2014-05-20 15:06                     ` Junio C Hamano
2014-05-21  0:45                       ` Jeremiah Mahler

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