[cvsnt] Re: virtual branches ?

[Tony Hoyle]

Matt Schuckmann wrote:
> Surely there is a need for it or else people like me and whomever 
> implemented the Move Branch to Head macro in WinCVS wouldn't be doing it.
> 
> If I remember right if a file changes on the main line but not on a 
> branch when you do a merge from the mainline to the branch a new 
> revision is created on the branch that is identical to the revision on 
> the mainline. In my mind this is wasteful and unnecessary. Plus it makes 

Revisions are a few bytes.. even if it created hundreds, even thousands 
of them it wouldn't make any difference.

What is important is reproducability - you need to be able to checkout a 
branch and get *exactly* what you got before, otherwise any testing done 
is meaningless.  That's the whole point of a source control system - and 
is why it's not uncommon to have the whole build system under revision 
control, not just the source code.

You can't simply move the branches around in many cases - the branch is 
a delta from the revision that it was created at.  Moving branches with 
revisions on is error prone and IMO dangerous.  Magic branches handle 
the non-revision case for the (rare) cases that it's useful (the 
original example was template configuration files with customer specific 
changes to a few of them).

Merging is a nontrivial operation for a reason - you can't just take two 
random branches and stick them together without operator intervention.

Tony