Branch from *part* of main code, how to keep it up to date?

Question

Was little bit difficult to formulate the title for my question since is kind of abstract...

Let me try to explain. I have a main code which has a git repository, I decided to take part of that code and make it a stand alone app. with its own name and versions to be distributed.

Is there a way to keep the main code and that other branch updated? ex. If I find a workaround for that code on Main, if I can merge that change to the stand alone (without adding any of the other functionality) as well as if I add a new feature on the stand alone, I would like to apply it to the main code as well.

Currently I have a branch but Im not sure If I will create its own git repository soon.

I am aware of git add -p but some times i have to many changes and going 1 by 1 until I arrive to the one I want to apply is sometimes a pain.

Any info would be appreciated

Answer 1

I believe what you want is in fact similar to a partial clone, for which is not supported in GIT.

Either put that "part" into a separate repository and make use of submodule, or create a branch for the standalone app and delete all unused stuff.

Answer 2

You can use git cherry-pick to grab individual commits and merge them into your current branch. Might be kind of annoying for long-running development, but it's one possible solution to your problem.

Answer 3

The tool most like what you describe is an add-on to Git, known as git-subtree:

http://github.com/apenwarr/git-subtree/blob/master/git-subtree.txt

It works a bit like submodules, but the projects aren't actually linked together, and you can extract and re-merge as much as you like. There are ongoing discussions regarding whether this tool will soon be distributed with Git itself.