Re: "svn diff" and "svn merge" sittin' in a tree

On Friday, February 15, 2002, at 01:36 PM, Mark Benedetto King wrote:

> On Fri, Feb 15, 2002 at 03:08:12PM -0600, Karl Fogel wrote:
> [...]
>> Yes, completely agree. Really perfect merging is much more
>> sophisticated than either diff+patch or diff3, and is non-trivial to
>> implement. Giving clients plug-in options is part of it (we'll have
>> to supply that fourth file -- the true common ancestor -- for them,
>> too!)

Would four files be enough information to implement variance-adjusted
patching? I have a hunch that it would, but I'll have to re-read the
paper. I remember the concepts, but not enough details.

> Speaking of four-file merges, the case that we've been talking
> about *does* have a use for them:
>
> imagine:

[snip example]

> Basically, Wander2 can put Change into foo:1/bar:1's "co-ordinate
> system"
> and Wander1 can translate *that* change into foo:3's "co-ordinate
> system".
>
>
>> The paper is www/variance-adjusted-patching.html, by the way. It
>> probably suffers from making up terminology for things that already
>> had accepted words, but the meaning is the same anyway.

Well, I for one, like "variance adjusted patching." But I may be equally
ignorant. :-)

> I mentioned this to Karl on IRC and he told me to read v-a-p.html,
> so I probably should.

Yup, it's essentially a detailed analysis of how to accomplish what you
describe above.

>> I don't think we're aiming for perfect merging right now. We just
>> need to be as good as CVS, and that means diff3 with three files, no
>> one of which is necessarily a common ancestor.

Agreed. Using a true 3-way merge tool is a big win over diff+patch
though, because the actual tool can be swapped out for a more
sophisticated version without changing the way svn would interact with
it.

Colin Putney www.whistler.com
Information Systems (877) 932-0606
Whistler.com (604) 935-0035 x221

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Received on Sat Oct 21 14:37:08 2006