On Thu, 2007-12-27 at 17:19 -0600, Les Mikesell wrote:
> Martin Marques wrote:
>
> >> CVS has problems caused by all of the history being kept in a single
> >> file (it doesn't understand directory operations like renames), but the
> >
> > Oh, and the fact that commits are not atomic so that if two chagesets
> > collide (well, CVS doesn't have notion of changeset, only of single file
> > changes) very bad things can happen (one changeset locks a file that the
> > other changeset has to update) and you get a corrupt copy that has to be
> > fixed.
> >
> > Subversion, git and Mercurial (and others) addressed this issue adding
> > atomicity to the chagesets (see that with these VCS files don't have
> > version there are changeset versions).
> >
> >> up side is that you can track development 'forwards' from any point.
> >
> > Uhh???
> >
> > $ hg up -r SOME_OLD_REV
>
> Start from a tagged point in development. Branch several times for
> different changes. Can you find all subsequent work?
This doesn't make sense from a SVN paradigm, and I'm pretty sure it's
just a difference of semantics. You _can_ d/l the entire repo, or if
you want to, follow revision numbers and see what was done. SVN keeps
trunk, tags, and branches isolated; if you follow the revisions of just
trunk, you only see the revisions of trunk.
> > (same with svn or git-update).
> >
> >> With svn, there's no way to start from an earlier tag and follow
> >> future tags/branches of that same file.
> >
> > What? Les do you really know what you're talking about?
>
> I'd like to hear that I don't. With CVS, if you have any of the
> development you have all of it. With svn, tags are (by convention) dead
> end snapshots and there is no way to track forward development. Assume
> you worked on something some time ago, ending by creating a certain tag.
> Now several other people create branches for additional work. How can
> you tell that, starting from the tag you last knew about? You could
> start from any of the branches and work backwards but you can't see what
> branches were created or when going forwards.
Yes, tags are by convention a dead-end. The concept of a "tag" is also
at the root of the concept of a "tagged release". I would say that by
convention, a release won't have anymore development done on it.
Branches are for the ability of making (possibly radical) changes
without disrupting the main trunk. Some branches merge back into trunk,
some don't.
> >> This must be even worse in distributed VC's where the changes might
> >> not even exist in your copy of the repository. Doesn't it bother you
> >> to know you might be repeating someone else's mistakes because you
> >> can't track all the other changes from a given point?
> >
> > What mistake if it's not in the repository?
>
> That's the point - you won't know.
A SCM is not a replacement for communication and normal team dynamics.
It is a tool to /help/ with managing and tracking changes to source
code.
> > The same thing would happen with CVS if you were coding without
> > commiting to the main server. Nobody will be able to know what you are
> > doing. Same if your coworkers don't update regularly. How can they know
> > what you fixed?
>
> If you aren't committing to the central repository, you aren't using CVS.
>
> > In distributed VCS you use pull and push for this.
>
> How can you tell whether that was always done or not?
>
> --
> Les Mikesell
> lesmikesell@xxxxxxxxx
That all said, if you like CVS, you like CVS. If an organization (i.e.
Fedora) wants to use a specific SCM, I'm sure there are reasons for it.
I would hope that in deciding what tool to use, one would weight all the
features and match them with your work habits/procedures/policies.
There's more than one way to skin a cat for a reason.
--Tim
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