Subject: Re: [ANNOUNCE] Example Cogito Addon - cogito-bundle

From: Aaron Bentley <[email-masked]>
Date: Fri, 20 Oct 2006 15:04:35 -0400

Linus Torvalds wrote:
> 
> On Fri, 20 Oct 2006, Linus Torvalds wrote:
> 
>>So yes, merges are the situation where renames are normally considered a 
>>"problem", but it's actually not nearly the most every-day situation at 
>>all.
> 
> 
> Btw, this is a pet peeve of mine, and it is not at all restricted to 
> the SCM world.

I guess I don't mind a bit of high-mmv discussion, so long as it doesn't
get in the way of real work.  Polishing these kinds of things seems to
fall in the category of 10% of functionality that takes 90% of effort.

> Of the rest, most by far need some trivial 3-way merging. And the ones 
> that have trouble? In practice, that trivial and maligned 3-way does 
> _better_ than anything more complicated.

I think the great motivator for exploring other merge algorithms has
been criss-cross merge.  There are some workflows (e.g. the Launchpad
workflow) in which heavy mesh-merging takes place, leading to frequent
criss-crosses.

Bog-standard three-way doesn't handle that criss-cross very well.  I
understand git uses recursive three-way in that situation.

The other motivator has been cherry-picking.

So I'm happy that people are trying to devise merge algorithms that are
better than three-way.  When someone gets it right, we'll implement it.

And then there are other more incremental tweaks, like
merge-across-indent and merge-across-line-ending-change that I'd like to
see.

> Go to revctrl.org for prime example of this. I think half the stuff is 
> about merge algorithms, some of it is about glossary, and almost none of 
> it is about something as pedestrian and simple as performance and 
> scalability.

Partly this is because of Bram's interests.  AIUI, he started with a
merge algorithm and built a VCS around it.

> (Actually, to be honest, I think some of the #revctrl noise has become 
> better lately.

I used to spend time on #revctrl, but I think that was before you
started visiting.  Too bad I missed ya.

 So maybe at least this area is getting more about
> real every-day problems, and less about the theoretical-but-not-very- 
> important issues).

It wouldn't surprise me if the early phases of VCS development tended
toward more theoretical discussion, just because so many questions are open.

Aaron