dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

On 17/06/11 11:04, Anders Logg wrote:
> On Fri, Jun 17, 2011 at 10:49:47AM +0100, Garth N. Wells wrote:
>>
>>
>> On 17/06/11 10:43, Anders Logg wrote:
>>> On Fri, Jun 17, 2011 at 10:33:23AM +0100, Garth N. Wells wrote:
>>>>
>>>>
>>>> On 17/06/11 10:28, Anders Logg wrote:
>>>>> On Fri, Jun 17, 2011 at 11:24:21AM +0200, Marie E. Rognes wrote:
>>>>>>
>>>>>> On 17. juni 2011, at 11:05, "Garth N. Wells" <gnw20@xxxxxxxxx> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 17/06/11 09:34, Anders Logg wrote:
>>>>>>>> On Fri, Jun 17, 2011 at 08:46:46AM +0100, Garth N. Wells wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 17/06/11 08:35, Garth N. Wells wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 12/06/11 21:36, Anders Logg wrote:
>>>>>>>>>>> On Fri, Jun 10, 2011 at 10:33:41PM +0100, Florian Rathgeber wrote:
>>>>>>>>>>> On 11/05/11 15:43, Anders Logg wrote:
>>>>>>>>>>>>>> On Wed, May 11, 2011 at 03:57:52PM +0200, Anders Logg wrote:
>>>>>>>>>>>>>>> On Tue, May 10, 2011 at 10:57:07PM +0200, Martin Sandve Alnæs wrote:
>>>>>>>>>>>>>>>> On 10 May 2011 17:52, Anders Logg <logg@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>> On Tue, May 10, 2011 at 03:49:18PM +0200, Martin Sandve Alnæs wrote:
>>>>>>>>>>>>>>>>>> On 3 May 2011 18:25, Johannes Ring <johannr@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>>>> On Tue, May 3, 2011 at 3:52 PM, Anders Logg <logg@xxxxxxxxx> wrote:
>>>>>>>>>>>>>>>>>>>> It happens to me a lot. Johannes has tried to explain to me why it
>>>>>>>>>>>>>>>>>>>> happens a number of times but I still don't understand why.
>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>> Maybe he can try to explain it again to you and then I might also
>>>>>>>>>>>>>>>>>>>> understand. :-)
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> I think I just bring up the following instructions (which I think looks good):
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> http://wiki.squid-cache.org/BzrInstructions
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Thanks Johannes.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Basically the problem is that bazaar numbers commits with contiguous
>>>>>>>>>>>>>>>>>> integers, and when Bob and Alice works locally they will get the same
>>>>>>>>>>>>>>>>>> commit ids for different commits. When you stand in branch Alice and
>>>>>>>>>>>>>>>>>> merge from branch Bob, the commit numbers of branch Alice are
>>>>>>>>>>>>>>>>>> conserved and a single new merge commit is recorded on top there. The
>>>>>>>>>>>>>>>>>> commit numbers from branch Bob are lost in the merge. Therefore, to
>>>>>>>>>>>>>>>>>> conserve the commit ids in the central branch, you have to merge from
>>>>>>>>>>>>>>>>>> your own branch into the server branch, not the other way around.
>>>>>>>>>>>>>>>>>> Otherwise we can never safely use the commit revisions from the
>>>>>>>>>>>>>>>>>> central branch, since they may change every time somebody merges the
>>>>>>>>>>>>>>>>>> 'wrong way'.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> This problem does not occur with hg or git, because they use a hash
>>>>>>>>>>>>>>>>>> value to identify a each commit.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> So if I'm Bob and Alice has pushed some changes to the main branch
>>>>>>>>>>>>>>>>> before me, which exact commands should I write?
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Depends on how you set up your repositories, where your branches are
>>>>>>>>>>>>>>>> located, etc...
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> You really have to read up on it and try it out a bit to understand
>>>>>>>>>>>>>>>> it, and I doubt I can write it better than what Johannes linked to +
>>>>>>>>>>>>>>>> the bazaar docs.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> I plan to keep a local repository with multiple branches like this:
>>>>>>>>>>>>>>>>  ~/dev/fenics/ufl/ - local ufl repository
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Is this a repository? Or is it just a directory named ufl inside which
>>>>>>>>>>>>>>> you keep a number of different repositories?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Talked to Martin during lunch. Here's a simple summary of what needs
>>>>>>>>>>>>>> to be done to set things up correctly (Cc to dolfin-dev so everyone else
>>>>>>>>>>>>>> sees this):
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>  bzr init-repo foo
>>>>>>>>>>>>>>  cd foo
>>>>>>>>>>>>>>  bzr checkout lp:foo trunk
>>>>>>>>>>>>>>  bzr branch trunk work
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> We should add this to the developer page in the documentation.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Everyone should adopt this and we should pick on anyone that pushes
>>>>>>>>>>>>>> removed changesets.
>>>>>>>>>>>
>>>>>>>>>>> There's an effective way to make these pushes impossible and disable the
>>>>>>>>>>> bzr "feature" of renumbering revisions: set the option
>>>>>>>>>>> append_revisions_only=True in <yourbranch>/.bzr/branch/branch.conf
>>>>>>>>>>>
>>>>>>>>>>> For branches on launchpad this works as follows:
>>>>>>>>>>> 1) sftp bazaar.launchpad.net
>>>>>>>>>>>     cd ~user/project/branch/.bzr/branch
>>>>>>>>>>>     get branch.conf
>>>>>>>>>>> 2) edit the downloaded file, adding append_revisions_only = True
>>>>>>>>>>> 3)   put branch.conf
>>>>>>>>>>>
>>>>>>>>>>> I suggest doing this for all branches on launchpad to enforce consistent
>>>>>>>>>>> revision numbers.
>>>>>>>>>>>
>>>>>>>>>>> More background: http://stackoverflow.com/questions/5413602
>>>>>>>>>>>
>>>>>>>>>>>> Thanks. I've fixed this now for DOLFIN, FFC, UFL, UFC, FIAT.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Could you please undo this. I can't push changes from my personal branch
>>>>>>>>>> to DOLFIN. I don't see that this change has any use. (If we want cvs,
>>>>>>>>>> then we should use cvs.)
>>>>>>>>>>
>>>>>>>>>> I've tried to follow the instructions to undo the change, but can't get
>>>>>>>>>> it to work.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I've undone this for DOLFIN so I could push my changes.
>>>>>>>>
>>>>>>>> You should have figured out how to do the merge properly instead. We
>>>>>>>> should add it back to force everyone to learn how to use bzr. ;-)
>>>>>>>>
>>>>>>>
>>>>>>> Merge is 'bzr merge xxx'. That's a proper merge.
>>>>>>>
>>>>>>>> The point is to not rewrite history for the common repo. This is not
>>>>>>>> the same as cvs. It's still distributed but it means merges have to be
>>>>>>>> done more carefully.
>>>>>>>>
>>>>>>>
>>>>>>> There is no history re-writing. It's just adding changesets. Unique
>>>>>>> changeset numbering that bzr does will always be problematic with
>>>>>>> distributed version control. If you want a unique identifier, use the
>>>>>>> revision id.
>>>>>>>
>>>>>>>> Just do this next time and it should work:
>>>>>>>>
>>>>>>>> 1. Make sure you have a local bound dolfin branch:
>>>>>>>>
>>>>>>>>  bzr checkout lp:dolfin trunk
>>>>>>>>
>>>>>>>> 2. Merge *from* that branch, not push to it:
>>>>>>>>
>>>>>>>>  cd trunk
>>>>>>>>  bzr merge <path to your local repo>
>>>>>>>>  bzr commit -m merge
>>>>>>>>
>>>>>>>
>>>>>>> It just worked before. It was simpler, and I could work against any
>>>>>>> branch, like by personal branch under dolfin-core.
>>>>>>>
>>>>>>
>>>>>> After trying the no-revisions-removed approach for a while, I also find it significantly more cumbersome, especially with the main vs personal branches.
>>>>>>
>>>>>> Although I see the point, I never encountered a problem with the changing revision numbers before.
>>>>>
>>>>> If Garth can't be bothered, maybe you could describe a specific
>>>>> example that doesn't work?
>>>>>
>>>>
>>>> Why would I bother with something that I think is pointless and
>>>> cumbersome? Like Marie, I have never had a problem with the present
>>>> approach.
>>>
>>> I disagree. I think there is a point to it and that it's not
>>> cumbersome.
>>>
>>> I'm just asking for a simple example that I can try. Otherwise it's
>>> just handwaving.
>>>
>>
>> You made the change, so the onus is on you to make a case, not the other
>> way around. I'm changing it back because I don't have any inclination to
>> change unless someone can make a case why. The status quo rules until
>> there is a consensus.
>>
>> What I don't want is to work in a CVS way. See:
>>
>>   http://wiki.bazaar.canonical.com/BzrForCVSUsers
>>
>> It advocates checkout for those who want to keep their CVS work flow,
>> and says of the approach:
>>
>> "This section explains how to perform common CVS behaviours in a Bazaar
>> world. Unfortunately, this means that I won't be able to teach you many
>> of the things that are unique to decentralized revision control systems.
>>
>> This section covers how to use Bazaar in checkout mode. Reading section
>> 3, which covers standard Bazaar methods, is highly encouraged."
>>
>> Section 3 describes what we've been doing all along.
> 
> I think you still need to make the case that it doesn't work. I claim
> it does and if you say that it fails so badly, it should be easy to
> come up with a single example of where it doesn't work.
> 
> I've already made the case for the change: to not change history of the
> common branch (which append_revisions_only prevents).
> 

Which I don't support. I also disagree with the technical point of
history changes.

A common branch is a centralised concept. I support developers using
separate feature branches, and using personal branches on Launchpad, and
the merging this into lp:dolfin.

Garth



> --
> Anders