Re: Tracking branch history

[Shawn Pearce <spearce@spearce.org>]

Junio C Hamano <junkio@cox.net> wrote:
> Shawn Pearce <spearce@spearce.org> writes:
> 
> > This is all well and good but its sort of useless without the diffcore
> > being able to lookup what SHA1 was valid on a given branch at a given
> > point in time.  :-)
> >
> > I'm thinking about extending the 'extended SHA1' syntax to accept
> > a date (or date expression) as a suffix:
> >
> > 	HEAD@'2 hours ago'
> > 	HEAD@'2006-04-20'
> > 	HEAD@'2006-04-20 14:12'
> >
> > etc... This would be merged into get_sha1 (sha1_name.c) so its
> > usable pretty much anywhere.  Does this seem reasonable?  If so
> > I'll work up a patch for it.
> 
> HEAD?
> 
> Are you going to hook into symbolic-ref as well to track branch
> switching?

I hadn't planned on it.  I was going to resolve the symref HEAD
down to the real ref (e.g. refs/heads/sp/ref-log) and then do the
date range searching on the real branch.  I didn't think it was
interesting to track what HEAD is.  But I think it would be very
common for the user to use HEAD rather than their actual branch
ref names when forming an expression.
 
[snip]
> The time-warp format would make sense for individual branches,
> like refs/heads/master, though.
> 
> sha1_name.c and sha1_file.c were supposed to be real core, but
> get_sha1() is looking more and more Porcelainish these days, and
> I do not have much problem with being able to say "tip of this
> branch, two hours ago".
> 
> I am not sure about the syntax though.  We would want to be able
> to say "start from the commit that was at the tip of 'master'
> branch two days ago, grab its tree and look at arch/sparc64
> directory", so things like
> 
>             "master@2006-05-14 14:12"
>             "master@2006-05-14 14:12^{tree}"
>             "master@two days ago:arch/sparc64"
> 
> would need to be supported.

Yea, I realize that.  I'm currently looking at get_sha1_1 and how
I can put the date resolution in before the ^, ~ and :.  :-)

-- 
Shawn.