Re: [PATCH 0/5] make interpret-trailers useful for parsing

On Thu, Aug 10, 2017 at 12:04:49AM -0700, Jacob Keller wrote:

quoted

quoted

  $ git log --format=%B -1 8d44797cc91231cd44955279040dc4a1ee0a797f |
    git interpret-trailers --parse
  Signed-off-by: Hartmut Henkel [off-list ref]
  Helped-by: Stefan Beller [off-list ref]
  Signed-off-by: Ralf Thielow [off-list ref]
  Acked-by: Matthias Rüster [off-list ref]

Thank-you, thank-you, thank-you.

The above example made me wonder if we also want a format specifier
to do the above without piping, but it turns out that we already
have "log --format=%(trailers)", so we are good ;-)

I was going to say, I thought we had a way to get trailers for a
commit via the pretty format, since that is what i used in the past.

I do like that you could get the trailers for many commits in a single
invocation. That doesn't matter for my current use-case, but obviously
piping through O(n) interpret-trailers invocations is a bad idea.

But there are a few difficulties with using %(trailers) for this, as it
shows everything between the start/end points of the trailer block. In
particular:

  1. You don't get any kind of normalization, so you're on your own for
     parsing things like whitespace continuation, extra spaces before
     separators, etc.

  2. It prints non-trailers that fall inside the block. For instance:

       $ git commit --allow-empty -F - <<-\EOF
       subject

       body

       Signed-off-by: me
       this is not a trailer
       Signed-off-by: you
       EOF
 
       $ git log -1 --format=%B | git interpret-trailers --parse
       Signed-off-by: me
       Signed-off-by: you

       $ git log -1 --format='%(trailers)'
       Signed-off-by: me
       this is not a trailer
       Signed-off-by: you

For (1) I think many callers would prefer to see the original
formatting. Maybe we'd need a %(trailers:normalize) or something.

I'm tempted to call (2) a bug, but I guess it's unclear whether callers
would want to see the whole block, or if they really want just the
individual trailers.

-Peff