Re: Overwriting trunk files with specific branch files

[Jim Hyslop]

Andy Jones wrote:
> > > cvs co -j HEAD -j t_branchA_tagA module
>
>
> Does anyone feel like explainaing how this is not a merge?  I don't get it.

It is a merge command, but it does not merge the changes from the 
branch. It will overwrite the head with the branch.

The command as shown is a shortcut to:

cvs co module
cd module
cvs up -j HEAD -j t_branchA_tagA

"cvs up -j REVA -j REVB", the merge command, applies the delta between 
REVB and REVA to the current directory. For a normal merge, REVA and 
REVB are normally on the same branch, thus you would get the changes 
from the branch merged into the changes on the trunk, i.e. trunk = trunk 
+ branch. But, in this case, REVA and REVB refer to the tip revisions on 
two different branches. The delta is Branch-HEAD, which when added to 
the HEAD, results in Branch.

Mathematically, this can be expressed as:

CWD = CWD + Delta

where CWD is the current working directory, and Delta is REVB - REVA. In 
this example CWD is HEAD, REVA is HEAD and REVB is Branch, so the 
equation becomes:

CWD = HEAD + Branch - HEAD

which simplifies to

CWD = Branch

It takes a bit to wrap your head around it, but it does work and do 
exactly what Christopher wanted.

--
Jim