git-timewarp

Oftentimes it's neccessary to go back to a previous commit. Perhaps you broke sometime and want to see where, or perhaps you want to benchmark an old version of a function. It's easy to git checkout, but what if you want to use two different versions of a function in the same script? Or use your latest testing/benchmarking code to run your old function? Fear not! git-timewarp allows you to temporarily import modules from a specified commit, performing all the git magic under the hood.

Here's how you use it. First, import the GitTimeWarp object. And the (current) version of a function you want to test.

from git_timewarp import GitTimeWarp
from test import test_func

Let's see the output of the current function

print(test_func())

new function output

Great. But what was the output of that function at an earlier commit? By entering a GitTimeWarp object, we can time travel to discover what it was. All in the same script!

with GitTimeWarp("a704acc5f651331645ee5850ff1cda0539cc23df") as tw:
    from test import test_func
    print(test_func())

old function output

Zounds! A ghost has appeared!

How does this work, you ask? The GitTimeWarp object simply checks out the old code in the timewarps/ folder (remember to add to your .gitignore!). It then modifies sys.path and does some more spicy python magic to ensure all imports in the block will reference the code in this other folder.