Overwrite to-be-installed source file (without overwriting the orignal file in the source directory)

I want to encode the git hash of the lastest commit at the time of installing as the output of a function in my library.

I am using a structure

.git/
setup.py
|- mylib/
|  - __init__.py
|  - git.py

whereby git.py contains a dummy, unconfigured, function

def git():
    return None

At the time of installing I want to overwrite git.py such that it returns the hash of the latest git commit, e.g.:

def git():
    return "2d04d1a10f81d24183df7622c95398d60106dfff"

(whereby the hash is the output of git rev-parse HEAD at the time of installing).

So my question: How can I overwrite the to-be-installed git.py, using setuptools, without overwriting the file in the source directory?

---

Current work-around setup.py

import subprocess

git_hash = subprocess.check_output(["git", "rev-parse", "HEAD"]).strip().decode('UTF-8')

cmd = '''def git():
    return "{0:s}"
'''.format(git_hash)

os.rename('mylib/git.py', 'mylib/git.py.bak')

with open('mylib/git.py', 'w') as f:
    f.write(cmd)

setup(
    name = 'mylib',
    version = __version__,
    # ...
    packages = find_packages(),
)

os.rename('mylib/git.py.bak', 'mylib/git.py')

Which has the down-sight of temporarily changing git.py in the source directory. I’d rather leave that file completely untouched.

See also: https://stackoverflow.com/questions/66265283/overwrite-to-be-installed-source-file-without-overwriting-the-orignal-file-in-t

[tdegeus]

Very clear, thanks once more!

[webknjaz]

It is based on Git tags. This plugin makes sure that the version is sourced from a file that you’re supposed to commit. It is a template git fills out when generating a git archive. This only works for tagged commits only, though. When running from a normal clone, it still uses the current repo.