Re: [PATCH 1/1] mingw: handle absolute paths in expand_user_path()

From: Duy Nguyen <pclouds@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Johannes Sixt <j6t@kdbg.org>,
	gitgitgadget@gmail.com, Git Mailing List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 1/1] mingw: handle absolute paths in expand_user_path()
Date: Fri, 9 Nov 2018 17:16:41 +0100	[thread overview]
Message-ID: <CACsJy8BzbEnXMRw6kB1rg+WMfu2wwJZWkAtVate98CZRSY_dLA@mail.gmail.com> (raw)
In-Reply-To: <20181109101918.GC7410@sigill.intra.peff.net>

On Fri, Nov 9, 2018 at 11:19 AM Jeff King <peff@peff.net> wrote:
> > The form `<RUNTIME_PREFIX>/abc/def` would not be confused with anything
> > that it is not, I would think. The only thing against this form (at least
> > that I can think of) is that some people use this way to talk about paths
> > that vary between different setups, with the implicit assumption that the
> > reader will "interpolate" this *before* applying. So for example, when I
> > tell a user to please edit their <GIT_DIR>/config, I implicitly assume
> > that they know to not type out, literally, <GIT_DIR> but instead fill in
> > the correct path.
>
> So yeah, some alternative syntax that is verbose but distinct makes
> sense to me. We use %-substitution elsewhere. Could we do something with
> that? "%RUNTIME_PREFIX%" gives me too many flashbacks, but something
> like "%(RUNTIME_PREFIX)" matches our formatting language.

FWIW I don't have any preference, as long as the variable can still
have a name (that is not a symbol).

A side question regardless of syntax. What do we do with
%(unrecognized name)/foo? I see three options

 - expand to empty, so "/foo"
 - keep it and try the literal path "%(unrecognized name)/foo"
 - somehow tell the caller that the path is invalid and treat it like
non-existing path, even if there is some real thing at "%(unrecognized
name)/foo"

The last option is more predictable. But we need to be more careful
about the syntax because if "%(some path like this)" actually exists
somewhere, then it will be broken. And I think it's also more work.
-- 
Duy