I am using git to manage a C++ project. When I am working on the projects, I find it hard to organize the changes into commits when changing things that are related to many places.

For example, I may change a class interface in a .h file, which will affect the corresponding .cpp file, and also other files using it. I am not sure whether it is reasonable to put all the stuff into one big commit.

Intuitively, I think the commits should be modular, each one of them corresponds to a functional update/change, so that the collaborators could pick things accordingly. But seems that sometimes it is inevitable to include lots of files and changes to make a functional change actually work.

Searching did not yield me any good suggestion or tips. Hence I wonder if anyone could give me some best practices when doing commits. Thanks!

PS. I've been using git for a while and I know how to interactively add/rebase/split/amend/... What I am asking is the PHILOSOPHY part.