Re: [PATCH v1 0/3] Introduce config variable "diff.primer"

From: Keith Cascio <keith@cs.ucla.edu>
Date: Jan 27, 2009, 01:47 UTC
Message-ID: <alpine.GSO.2.00.0901261734360.16158@kiwi.cs.ucla.edu>
In-Reply-To: <20090125220756.GA18855@coredump.intra.peff.net>

On Sun, 25 Jan 2009, Jeff King wrote:

Show 17 quoted lines

> let's say I have a gitattributes file like this:
>    *.c diff=c
> and my config says:
>   [diff]
>     opt1 = val1_default
>     opt2 = val2_default
>   [diff "c"]
>     opt1 = val1_c
> 
> Now obviously if I want to use opt1 for my C files, it should be val1_c.
> But if I want to use opt2, what should it use? There are two reasonable
> choices, I think:
>   1. You use val2_default. The rationale is that the "c" diff driver did
>      not define an opt2, so you fall back to the global default.
>   2. It is unset. The rationale is that you are using the "c" diff
>      driver, and it has left the value unset. The default then means "if
>      you have no diff driver setup".

I'm in favor of option (2), because [diff] a.k.a [diff ""] serving as the fallback for [diff *] feels like a special case. If a full system of precedence and fallbacks is desired for .git/config, we should adopt explicit grammar that lets me define an arbitrary precedence tree over all sections. Once a powerful concept is born, somewhere down the road, some user will desire its universalization.