Re: Removing rollback from VC mode - request for comment

[Eli Zaretskii]

> Date: Thu, 11 Dec 2014 07:51:45 -0500
> From: "Eric S. Raymond" <address@hidden>
> 
> Thien-Thi Nguyen <address@hidden>:
> > So, i think "rollback" as a concept is actually not far
> > enough.  Being able to select arbitrary commits to drop (like
> > ‘d’ and ‘x’ in Dired) is what i'd like to see, in its stead.
> 
> RCCS and SCCS can do this, in theory.  But I've never trusted that
> feature.  The obvious problem is that if you delete an earlier delta
> you may well change the preconditions for a later one, so it will have
> unexpected effects.  
> 
> I know how RCS's delta representation works; it is *not* smart enough
> to fully compensate.  And no wonder. General patch composition is a
> hard enough problem that it scuttled Darcs thirty years later!
> 
> In other VCSes it would be difficult to even attempt this.

??? It's known as "reverse cherry-picking", and is AFAIK possible in
Git, bzr, and hg.

Or maybe I don't understand what ttn was alluding to.