Re: [PATCH] expose svn_repos_replay via the RA API, Take 2

On Wed, 2005-11-16 at 17:02 -0800, Jim Blandy wrote:
> We must be disconnected. How can it possibly not be well-defined to
> compose deltas?

Because our deltas aren't expressed wholly in terms of the previously
existing contents of the tree. If we have:

  r1: add foo (no history)
  r2: delete foo
  r3: add foo (copy history foo@1)
  r4: add bar (copy history foo@1)

Then what is the composition of r1-r4?

I believe most modern SCMs, particularly ones that have to deal with
distributed operation, restrict deltas to referring to the previously
existing contents of the tree. That means you can't express the
resurrection of a file, but it makes composition well-defined. Although
I believe they also tend not to do delta composition so much, and just
transmit whole batches of deltas around.

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Received on Thu Nov 17 07:50:10 2005