Re: [Monotone-devel] Re: Delta storage

[Nathaniel Smith]

On Fri, Oct 14, 2005 at 04:43:19PM +0200, Zbynek Winkler wrote:
> Bruce Stephens wrote:
> >Not all deltas are reversible.  If the delta B->C says "delete lines
> >38-57", then that doesn't let you construct the delta C->B.  (monotone
> >stores binary deltas of the xdelta form, I believe, but I think the
> >same sort of thing can happen in those.)
> > 
> I see. I guess I was thinking more in the terms of patchfiles and the 
> lines with "+" or "-" at the beginning. So the question is - are all 
> deltas in monotone reversible? I remember something about reversing 
> deltas for the 'update' command when updating working copy to be based 
> on a different revision before commit...? That revision doesn't need to 
> be a parent, it can be a sibling...

No, xdeltas are not reversible.  Efficient binary diffs generally
aren't; normal textual diffs are, but they're way more expensive to
calculate and generally larger...

-- Nathaniel

-- 
In mathematics, it's not enough to read the words
you have to hear the music