Variance adjusted merging, WAS: RE: svn commit: rev 5275...

> From: striker@tigris.org [mailto:striker@tigris.org]
> Sent: Tuesday, March 11, 2003 10:36 AM

> (svn_diff4): New function. Return a variance adjusted diff between
> original, modified and latest, using ancestor.

'diff4? What the heck is that?', were the initial responses when I
mentioned it, so this deserves an explanation. In time this will be
tweaked in a nice docstring, but for now this has to do.

First take a look at:

  http://subversion.tigris.org/variance-adjusted-patching.html

With the second example in mind, consider the following datasources to be
defined as follows:

original == T:2
modified == B:2
latest == T:3
ancestor == T:1 == B:1

svn_diff4 starts by doing a diff between original and latest, which it
then translates into a diff between original, modified and latest.
The result can be directly used to feed through a diff3 output function,
which is exactly what the diff4-test program does.

For people who wish to experiment, please try the diff4-test program
and report your findings. Something tells me something like this would
be very nice to have embedded in svn merge, where svn provides the
ancestor or falls back to diff3 if there is none. It probably needs
a flag to be turned off too, for our paranoid crowd ;).

For the record: diff4 is experimental. I've only hand tested it on
example 2 in the variance adjusted patching document. It needs a
full workout before it can be used in production.

Sander

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Received on Tue Mar 11 11:18:22 2003