Subject: Re: [PATCH v3 05/13] parse the -L options

From: Thomas Rast <[email-masked]>
Date: Tue, 20 Jul 2010 00:48:17 +0200

Junio C Hamano wrote:
> It almost feels as if you want to have something more like
> 
>     -L <begin>,<end>[,<path>]
> 
> where <path> is mandatory for the first use of -L (i.e. missing ,<path>
> means the same path from the previous -L that has one) to make it clear
> that this is completely different from the normal pathspec.

I think that would just needlessly break the analogy to git-blame.[0]
With the current code,

  git blame -L 2,3 <path>
  git log -L 2,3 <path>

work the same.  Multiple -L options could be retrofitted to git-blame,
making

  git {blame,log} -L 2,3 -L 4,5 <path>

work as expected.

As long as you only give a single path, even blame disambiguates in
favour of the filename:

  git blame -L 2,3 master # wants a file 'master'

It only starts breaking down as soon as you put the -L further away
from the filename:

  git blame -L 2,3 master master # looks for the file master:master
  git blame master -L 2,3 master # ditto
  git log -L 2,3 master master   # errors out since the second file has no -L [1]
  git log master -L 2,3 master   # looks for the file master:master

And as you have noted, the -- can also cause weird effects.  Currently

  git log -L 2,3 --branches      # error
  git log -L 2,3 ./--branches    # ok
  git log -L 2,3 -- --branches   # error

The last one is unfortunate, but fixing it while allowing a natural
positioning of the -L would require parsing the -L after a --.  That's
just as inconsistent, only in a different way.

[0] It also requires special support from shell completion.

[1] I agree with erroring out but I think the message wrongly
    recommends path filtering (since that doesn't work well with
    renames):

      fatal: Path master need a -L <range> option
      If you want follow the history of the whole file whether to using 'git log' without -L or using 'git log -L 1,$ <path>'

    Bo, can you please change it to e.g.:

      fatal: Path 'master' needs a -L<range> option
      If you want to follow the history of the whole file, use 'git log -L 1,$ <path>'

-- 
Thomas Rast
trast@{inf,student}.ethz.ch