Re: LCA2006 Git/Cogito tutorial

On Sun, 23 Oct 2005, Junio C Hamano wrote:

The current callers only feed commits for "$heads" parameters,
so the merge strategy backends are free to figure out the common
ancestor or even generate weave on the fly, but an unwritten
rule was that strategy backends are expected to do something
sensible even when the "common ancestors" and "heads" fed to
them are tree objects, which was my comment about 3-way was
about.

Ahh. Yes, if you use raw trees, you're screwed - you can only ever do a 
3-way merge, since you can't try to figure out any history.

I agree that the "tree only" case is interesting too - it's how you can 
merge trees that may be related content-wise but don't share a history (eg 
the same project maintained in separate source trees), and it's obviously 
how you can merge totally unrelated projects (eg the gitk merge). At the 
same time, I think that's a different kind of merge, in general. And we 
definitely shouldn't limit ourselves to things where such merges work.

Yes, tree-merges are wonderful, and they work really quite well, but I 
definitely want to keep the window open for merges that end up taking the 
full history into account.

I just don't think they are nearly as important as some people seem to 
think. They should be a very special and unusual case, rather than 
something you expect to happen.

		Linus