[darcs-users] revision identifiers

[David Roundy]

On Fri, Mar 28, 2008 at 06:48:32PM +0100, Declan Naughton wrote:
> On Fri, Mar 28, 2008 at 5:58 PM, David Roundy <droundy at darcs.net> wrote:
> > On Fri, Mar 28, 2008 at 05:26:27PM +0100, Declan Naughton wrote:
> >  > Why can't checksumming the context produce a suitable identifier, I
> >  > must ask? What are the uses in it being "universally unique" that we
> >  > would miss out on, anyhow? We can still seek through the repository
> >  > history and get specific revisions?
> >
> >  The checksum of a context wouldn't allow us to determine what context it
> >  describes, since the number of possible contexts we'd need to try goes as
> >  N!, where N is the number of patches in the repository.  I think that'd be
> >  a bit too expensive.  Best to just include the entire context.
> 
> We don't need to generate a sum for every possible context, just one
> sum for the actual context at every point in time (every time a record
> takes place).

What is it that you propose to do with these sums? I thought you wanted to
communicate them to another user.  If you do that, then that other user
will have to face O(N!) complexity in order to interpret the sum you sent
them (except perhaps if they have your repository).
-- 
David Roundy
Department of Physics
Oregon State University