In magit, I want to (easily) see how a piece of code changes over time with commits

Question

I'm curious if there's an easy way in Magit to see how a piece of code changes over time, i.e., with each commit.

I'd like to have one window open in Emacs, focusing on the code/function I want to see changes to, and another window (e.g., Magit log buffer or something) where, when I move up/down in the history of the file in the other window, I can see it evolve over time.

I've thought about this for a long time, but I've never been able to find it in the manual or even know what kind of keywords to look for. I hope I managed to explain it this time and someone out there understands what I'm talking about.

Answer 1

You can do this with vc or with magit:

• C-xvh runs the command vc-region-history.

• Using Magit, the equivalent command magit-log-buffer-file (l in the magit-file-dispatch menu; hence commonly it would be C-cM-gl).

With either of these commands you firstly mark a region you are interested in, and they then give you (in a single buffer) a history of that region: the sequence of commits which affected the region, and the diff for each of those changes.

As such, a useful prefix is often C-M-h which runs the command mark-defun.

Answer 2

It’s not exactly what you describe, but there is magit-blame-addition.