Question

We have a super project which has a couple of sub modules, this has been working well.

But now we have reached the point where in one of the sub modules needs to be modified for this specific project, but still want to be able to pull in changes from original sub module if possible.

We want these changes to be tracked by the super project obviously, and not be pushed through to the original sub module if we make a change.

How can we manage this?

I imagine we could create a branch in the sub module for this specific project, but that could get messy with 100+ projects using the same sub module.

Answer 1

I don’t know the details of your projects/subprojects, so I will only give vague and general observations.

Your issue does not seem to be with git specifically, but rather with managing projects/subprojects dependencies.

First a word of warning : from what you are describing, you want to tweak the behavior of a submodule used by 100+ projects for only one of these projects. If you really end up modifying the submodule (e.g : modifying the code also used by the other projects), you are entering one new circle in the hell of testing. Look at how your submodule works, and determine if you should really change your submodule, or only tweak it for one project.

If the modifications you need are only specific to one project, try to keep these modifications confined to the project – and not modify the submodule.

One possible way would to wrap its call in the specific project, e.g replace calls to :

submodule::do_stuff()

with

function adjust_behaviour(){
    result = submodule::do_stuff();
    tweak_for_my_project(result);
    return result;
}

If the behaviour of your submodule should really change depending on a parameter, you should display this in the interface it provides to use it.

For example : if your submodule contains a function computeThis(), and the computation actually depends on the parameter weather, you should consider changing the function so it acts accordingly : computeThis(weather).

Or maybe your sumodule can load a configuration file, and each project should provide its own.