[Numpy-discussion] Moving away from svn ?

David Cournapeau david at ar.media.kyoto-u.ac.jp
Sun Jan 6 04:38:56 EST 2008


Robert Kern wrote:
> 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.
> """
>
>   
Does good merging only depends on the above ? Martin Pool, one of the 
bzr programmer, wrote this article two years ago:

http://sourcefrog.net/weblog/software/vc/derivatives.html

which I found both enlightening and easy to follow.

cheers,

David



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