Re: [PATCH v2] config: add '--sources' option to print the source of a config value

From: Jeff King <peff@peff.net>
Date: Feb 10, 2016, 15:40 UTC
Message-ID: <20160210154006.GA19867@sigill.intra.peff.net>
In-Reply-To: <CAHGBnuMMN_xEVDJ_dqWgL6QCGK08hy=ggg=6PzkSCinHr=QeFg@mail.gmail.com>

On Wed, Feb 10, 2016 at 04:33:11PM +0100, Sebastian Schuberth wrote:

Show 16 quoted lines

> > where two of the prefixes have nothing in the second slot. I expected
> > something more like:
> >
> >   file:<filename>\t</value...>
> >   blob:<blob>\t<value...>
> >   stdin\t<value...>
> >   cmd\t<value...>
> >
> > with a single delimited slot for the source, which can then be broken
> > down further if desired.  I can't think of any reason to prefer one over
> > the other rather than personal preference, though. They can both be
> > parsed unambiguously.
> 
> I also would have expected sopme like the latter, except that I'd also
> expect a colon after "stdin" and "cmd" (or "cmdline", as said above).
> I.e. the colon should be part of the prefix to mark it as such.

Yeah, I waffled on that. Having a colon means you can definitely parse to the first ":" without looking at what the prefix is. But if you don't know what the prefix is, I don't know what good that does you. IOW, I'd expect it to be parsed like:

  if (/^file:(.*)/) {
    # source is file $1
  } elsif (/^blob:(.*)/) {
    # source is blob $1
  } elsif (/^stdin/) {
    # source is stdin
  } elsif (/^cmdline/) {
    # source is cmdline
  } else {
    die "eh? I don't know about $_ at all!"
  }

That's perl, but I think most languages make prefix-parsing like that easy. I dunno. I doubt it matters all that much, and we are deep into personal preference. There's already plenty to bikeshed on the option name :)

-Peff