Re: [PATCH 2/4] log and rev-list: Fixed newline termination issues with --graph

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 7, 2008, 08:52 UTC
Message-ID: <7vwsnaoxlz.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <7vod8mqdlw.fsf@gitster.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 11 quoted lines

> I suspect that --pretty=format: (i.e. userformat) should have a way to
> explicitly tell which is wanted.  Perhaps we can keep the separator
> semantics not to break existing users, and introduce a dummy expand item
> (say, '%_') and when it appears in the pattern it would ask for the
> terminator semantics instead?
>
> In any case, I'm happy to see that somebody started looking into this, as
> this "separator vs terminator" issue in userformat has been nagging me for
> quite a while.  It might be good idea to have the change independently
> from the graph extension first and then build the graph stuff on top of
> the solidified base.  I dunno...

Some alternatives to specify terminator semantics I considered are:

 (1) Presence of %_ in "--pretty=format:..." triggers terminator
     semantics and %_ itself interpolates an empty string; otherwise
     separator semantics is used.

 (2) Presence of %n in "--pretty=format:..." means a multi-line output and
     uses separator as before; lack of %n means it is a one-line format
     and uses terminator.

 (3) A new option --pretty=tformat:... (i.e. tformat instead of format)
     means LF (or NUL) is used as terminator instead of separator;

 (4) A new syntax --pretty=format/... (i.e. slash instead of the usual
     colon) means LF (or NUL) is used as terminator instead of separator;

The first one is what I suggested in the message, but it feels somewhat hacky. I suspect that the second one would catch 99% of the cases, but it is DWIM and it is known that DWIM can go wrong. I favor design along the lines of (3) or (4), which I think would be much cleaner.

I however do not particularly like either "tformat" which is a non-word, nor ":" vs "/" whose differences do not intuitively translate to "separator vs terminator" distinction.