Why not Subversion + DVCS of Choice?


A follow-up to my last post on DVCSes…

Gnomers have been discussing DVCSes a lot lately, and at least one seems to prefer bzr as the repository format and git as the protocol it speaks. If this sounds like madness to you, you’re not alone.

What I don’t understand is why more people don’t choose to keep Subversion as their repository and just use the $DVCS-svn of your choice?

Granted I’ve only used bzr-svn a bit, but it worked quite well and seems to only be getting better. I hear git-svn is quite good as well (but iirc hg lags behind the competition).

The benefits of this seem pretty nice:

  • Repository and Project management tools could get by with only first class Subversion support.
  • Directing inexperienced users to download code would be standardized.
  • Linux distributions wouldn’t have to ship 5 different VCSes (cvs, svn, git, bzr, hg), although the VCSes don’t take up much space.
  • Developers could use whichever tool they preferred, publish branches to any one of the zillions of free hosts for their DVCS of choice, and get on with their life.

Answering my own question…

The obvious counter argument is that in order to share code you either:

  • …force everyone who cares to use your DVCS.
  • …or lose some of the benefits of your chosen DVCS and share code via a SVN branch.

Lets face it, both options are a pretty big hassle for developers. Comprises always are.

For smaller single projects the overhead associated with going this route probably isn’t worth it. You’ll probably either end up losing 75% of what makes a DVCS handy or just use SVN.

Why is Gnome not considering this option though?

This option seems ideal for projects like Gnome. Individual modules will probably adopt a preferred DVCS, and thats fine. None of them are so different that a competent developer couldn’t yank some revisions from an unfamiliar DVCS.

The project as a whole (and individual modules) would continue to remain uniformly easily available through a single svn checkout.

At the very least isn’t this better (at least saner) than bolting git onto bzr’s repository format?

Audience Participation

I’m not a Gnome developer though. Just a curious user. However, as a fellow developer I am left wondering: why isn’t this a good option? Are $DVCS-svn connectors just not good enough? Are the comprises too great? Or the most likely: am I just missing some obvious showstopper?