[Numpy-discussion] Moving away from svn ?

Robert Kern robert.kern@gmail....
Sun Jan 6 03:38:44 CST 2008


Bill Baxter wrote:
> http://www.selenic.com/mercurial/wiki/index.cgi/MergeProgram
> 
> This is a bit puzzling.  I understand better merging isn't the only
> reason to choose DVCS, but the above page basically says that
> Mercurial just uses whatever external merge program it can find.  So
> the file-level merging sounds like it must really be no different from
> other VCSs.
> 
> So it is really just proper merging of directory renames and the like
> that make it superior?

No. If you'll pardon my repeating myself:

"""
DVCSes need to keep track of more information in order to be
distributed. That information is extremely useful for managing merges properly.
Centralized systems could track this information, but they don't *need* to in
order to be functional, so they mostly haven't, yet.

For each revision, the DVCS knows what revisions it derives from. SVN does not
keep this information. SVN primarily just knows the text diffs from revision to
revision. In particular, if I have a long-lived branch, I am going to merge in
changes from the trunk while I'm working on it. When I go to merge the branch
back into the trunk, I need to know which trunk-revisions I've already merged
into the branch. SVN does not track this information. Tools like svnmerge.py
track some of this information at the expense of some added clumsiness.
"""

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco


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