Re: Multi-headed branches (hydra? :)) for basic patch calculus

["J. Bruce Fields" <bfields@fieldses.org>]

On Sun, Apr 02, 2006 at 04:07:32PM +1200, Sam Vilain wrote:
> To represent this in git you could just roll back the head merge commit,
> push commit 5 on that branch, then make a new head:
> 
>   1 -> 3 -> 5 \
>                >- head
>   2 -> 4 -----/
> 
> However, if there was support for "hydra", or heads that are multiple
> commit IDs (and necessarily, no blobs in corresponding paths in their
> trees that are not identical), then you would not need to destroy and
> recreate this dummy merge head commit to model your patch history in
> this manner.

What's the advantage to doing this?

> If the plumbing or a porcelain could be smart enough to automatically
> create hydra when patches are not dependent, then many of the benefits
> of patch calculus might come for free, without having to create these
> complicated sounding entities manually.

What are the benefits of patch calculus?  (What is it?  The only
explanation I've seen is at
http://abridgegame.org/darcs/manual/node8.html, but I don't find it very
helpful.)

--b.