How Bazaar works

[Daniel Carrera]

Hello,

I'm on the mailing list of another DVCS called fossil and someone there 
made a comment about other DVCS tools which doesn't sound right at all:

<quote>
Consider the case of hg or darcs or some other such distributed system 
which conflates the repository and the working set.  I'm working on a 
project, so I clone a remote repository into a local directory.  I make 
changes to feature A.  While I'm working on A, I get a high-priority 
request to work on feature B.  Either I clone the remote repository 
again (needs network, needs time, hits the remote server harder in a 
large project, wastes space as the repository itself is recopied, etc.) 
or I clone my local copy in A (which just wastes the space).

Let's say we took the second option.  While I'm working in B, I finish 
my work in A.  I push my changes and delete A ... and WHOOPS!  I just 
screwed up B, didn't I?  B is expecting A as an uplink which is now gone 
because the distinction between the working set and the repository is 
fuzzy.  I can reseat B to point to another copy of the repository (and 
hope that that repository doesnt' have changes which clash with the 
changes I made in A and in B) but I think anybody can see that this is 
not a particularly good solution.
</quote>


This doesn't sound right. The idea that each branch is dependent on 
another branch, forming some sort of DAG tree, seems wrong. I expect 
that in any decent distributed SCM, each branch is equal and 
independent. So if you create branch A, then from there create branch B, 
from that point on B is totally independent on branch A, and it doesn't 
matter if you delete A.

When I expressed my doubt that distributed SCMs work like this (I know 
that Darcs doesn't) another poster assured me that this is true:

<quote>
When you clone REMOTE to A, a note is made in A that you cloned from
REMOTE.  So when you are working in A and you push or pull or sync it
knows that the endpoint of that operation is REMOTE.

When you clone A to B, a note is made in B that you cloned from A.  So
when you are working in B and you push or pull or sync it knows that the
endpoint of that operation is A.

Then you delete A.  And you go into B and make some changes, and commit,
and push.  And it says "Can't.  A is missing".  And you have to
explicitly tell it that you want to sync with REMOTE instead of A.
</quote>


On a second reading, maybe the guy is just saying that when you push you 
have to put the URL of the repository you are pushing to. If so, that's 
not a dependency!

Any comments?

Daniel.