MicrobranchingEdit
Microbranching, better known as "using topic branches", is a technique that I use when I wish to develop a specific, small feature without distrupting the main line of development or degrading its stability. It is also commonly used when submitting patches to an "upstream" project which you do not control; you group together a logical set of changes on a "topic branch" where they can be easily managed (revised, or kept up to date using rebasing) and then submitted as a patch series (see "Creating and submitting a patch via email with Git").
The technique consists of creating a local-only branch using a branch-savvy version control system such as Git or SVK, working on the feature, and then using git merge
, svk push
or similar to propagate the changes back to the trunk, or publishing them upstream as a patch series sent via email (for projects which you don’t control directly). These topic branches or microbranches are short-lived.
An example using SVK
This is an example of a creating a microbranch for the purposes of adding the #include
directive to Walrus. This feature is well-suited to a microbranch because it is a relatively complicated directive (it requires a sub-parser to be spawned for each included file) but it is still reasonable to implement it within a short time frame (no more than a few days).
Creating the branch
# use the "-p" switch to create "//local/Walrus/" if needed
svk cp -p //mirrors/Walrus/trunk //local/Walrus/include-directive \
-m "Microbranch for implementing '#include' directive"
# check out a working copy of the microbranch
svk co //local/Walrus/include-directive include-directive
# make sure all specs pass
cd include-directive
rake make
rake spec
Pulling changes in from the trunk
# use the "-p" switch to create "//local/Walrus/" if needed
svk cp -p //mirrors/Walrus/trunk //local/Walrus/include-directive \
-m "Microbranch for implementing '#include' directive"
# check out a working copy of the microbranch
svk co //local/Walrus/include-directive include-directive
# make sure all specs pass
cd include-directive
rake make
rake spec
It’s unlikely that any changes will be made on the trunk while working on this feature because this will be such a short-lived branch.
svk pull
Pushing back changes
svk push --verbatim
svk push --verbatim
The --verbatim
switch prevents SVK from including SVK-specific meta-information (such as local revision numbers) in the log entries.
Disposing of the microbranch
svk co --detach
cd ..
rm -r include-directive
Updating existing copies of the trunk
svk co --detach
cd ..
rm -r include-directive
Assuming there is a checked-out copy of the trunk in src
:
cd src
svk up -s
And again ensuring that all specs pass:
rake spec