[darcs-users] obsolete markers for save "rewriting" of history

[Ganesh Sittampalam]

Hi Petr,

On 23/02/2013 09:47, Petr Pudlák wrote:

> Recently I've been told that mercurial is working on a concept that
> allows to safely "rewrite" history. As I understand it, it actually
> doesn't modify anything, it just adds specific information (markers)
> that signals that some  commits should be invisible or visually replaced
> by something else. These markers are propagated between repositories
> just as other stuff so working with them is fully distributed and the
> history of what has been done is preserved. See
> http://mercurial.selenic.com/wiki/ChangesetEvolution
> 
> I wonder, would it be possible/difficult to add something like that to
> darcs?

We actually spoke to one of the developers of the mercurial feature at
our recent sprint, and were quite impressed. We'd previously vaguely
considered this kind of thing but were put off by the general idea of
versioning patches - it just seemed like a step too far. But it sounds
like it works well in the mercurial case and we could do something similar.

So if there's general agreement on this I think it's just a matter of
implementation :-)

Roughly speaking we'd want markers that say "patches X,Y,Z obsolete
patches A,B", and we'd also want something like the mercurial notion of
"phases". My gut instinct would be for something a bit more general than
the just three phases, but perhaps that's over-complicating things.

Cheers,

Ganesh