Re: Alternative approach to the git config NULL value checking patches..

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 11, 2008, 08:12 UTC
Message-ID: <7vzlu7ap2y.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <200802110822.08902.chriscool@tuxfamily.org>

Christian Couder <chriscool@tuxfamily.org> writes:

Show 18 quoted lines

> Now the 10% are only when we have a boolean variable and we want it to 
> be "false" when there is:
>
> [foo]
> 	var =
>
> while:
>
> [foo]
> 	var
>
> is considered "true".
>
> And let's face it, it's not obvious at all why it should be false if there 
> is "var =" and true when there is only "var". Is it a Microsoft standard ?
> Do we really care about it ?
> ...
> I also doubt that many users willingly use "var =" to mean "false".

Some variables started their life as boolean and "[foo] var" is true and "[foo] var = false" (or "= 0") is false for them; later they acquired third or more options to have string values.

For such a variable:

	[foo] var	    ; boolean "true"
        [foo] var = "true"  ; boolean "true"
        [foo] var = "false" ; boolean "false"
	[foo] var = ""	    ; boolean "false", too.
        [foo] var =         ; perhaps misspelled, perhaps the same as above.
	[foo] var = "value" ; string (new semantics)

and adding a warning for the fifth one (but not fourth one) might be a good idea.

I have a bit stronger opinion on keeping "[foo] var" (without an equal sign) to stay "true". Especially, making it exactly the same as an empty string is unacceptable, if it is done without Linus's trick to make it distinguishable internally.

Luckily, the calls to get_config_set() we internally make in-tree (e.g. git-init sets core.filemode and friends) are all very explicit and do not write "[foo] var" form of truth. But many existing docs written outside our (my) control that google finds say "Put '[core] autocrlf' in your .git/config". You do not want to break the repositories configured following such an advice.

> So let's do them (and ourself too) a favor and deprecate "var =" to mean 
> false. I will post my patch to do this.

Don't do it if you cannot differentiate between the fourth and the fifth in the above listing.