Lower minimum Python version to 3.7

[pkalita-lbl]

Fixes #7

[pkalita-lbl]

Gah! Tests were passing with Python 3.7 locally, but after merging main into this branch they no longer pass because of from importlib import metadata in src/prefixmaps/__init__.py. importlib.metadata was added in Python 3.8 🤦🏻

@hrshdhgd do you know any way to make that import backward compatible?

[hrshdhgd]

hmm .... how crucial is supporting python v3.7.x ? I was under the impression we had decided to support everything > v 3.8.0. This may be a Chris question.

I do not know what we could do for backward compatibility right at the top of my head. I'll start looking.

[pkalita-lbl]

I want to use this in the linkml project. So either this has to go down to 3.7.6 (the current minimum for linkml) or linkml has to go up to 3.8.0.

[hrshdhgd]

I think the latter option is a more easy solution.

[cmungall]

If we like from importlib import metadata we should use this universally

does this work for our current release mechanism?

[hrshdhgd]

Yes. It gets the __version__ from one place in the project (the toml file) as opposed to hard-coding it in different places.

[pkalita-lbl]

There is a compatibility package (https://github.com/python/importlib_metadata) but it seems like it's getting tripped up on the src directory structure.

[hrshdhgd]

Oh yeah! for the import we could do a if else statement that checks the python version and depending on that, the import statement could be modified. I remember seeing this somewhere specifically for importlib vs importlib-metadata.

[hrshdhgd]

I meant try-except not if else

try:
    from importlib import metadata
except ImportError: # for Python<3.8
    import importlib_metadata as metadata
__version__ = metadata.version(__name__)

[pkalita-lbl]

Yeah that's what I was attempting to do, but I keep getting this when I run the test suite:

ImportError: Failed to import test module: src.prefixmaps
Traceback (most recent call last):
  File "/Users/PAKalita/.pyenv/versions/3.7.13/lib/python3.7/unittest/loader.py", line 470, in _find_test_path
    package = self._get_module_from_name(name)
  File "/Users/PAKalita/.pyenv/versions/3.7.13/lib/python3.7/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/Users/PAKalita/Work/prefixmaps/src/prefixmaps/__init__.py", line 6, in <module>
    __version__ = version(__name__)
  File "/Users/PAKalita/Work/prefixmaps/.venv/lib/python3.7/site-packages/importlib_metadata/__init__.py", line 585, in version
    return distribution(distribution_name).version
  File "/Users/PAKalita/Work/prefixmaps/.venv/lib/python3.7/site-packages/importlib_metadata/__init__.py", line 558, in distribution
    return Distribution.from_name(distribution_name)
  File "/Users/PAKalita/Work/prefixmaps/.venv/lib/python3.7/site-packages/importlib_metadata/__init__.py", line 215, in from_name
    raise PackageNotFoundError(name)
importlib_metadata.PackageNotFoundError: No package metadata was found for src.prefixmaps

[pkalita-lbl]

Wait, that error was the result of trying to run poetry run python -m unittest but I don't get that when trying to run poetry run pytest. So maybe that's more of a unittest issue than a importlib_metadata issue??

[hrshdhgd]

I agree. I just ran pytest (since I do it for all projects I work on) and it seems to work.

[pkalita-lbl]

I've added the change to import from importlib_metadata as a fallback. Everything seems to be passing now. Any final comments on this?