TIL: importlib.metadata.version #
Apparently __version__ can be dynamic now.
While I was updating my standard pyproject.toml to use dependency groups, I switched to using uv as my build backend (from setuptools). Like all the other design choices, it has very sensible defaults with good overrides when you need them.
One thing that it doesn't support is dynamic versions (i.e. reading __version__ from __init__.py). Charlie Marsh explains:
Using dynamic metadata for things that are actually just static lookups feels like the wrong tradeoff.
Like
version = ["dynamic"]to read the version from__init__.py.As soon as you have dynamic metadata, you need to install dependencies and run Python just to get that info.
Static metadata rules. Just write the version out twice!
This makes sense, but I really didn't want to write out the version twice. Luckily, uv has a nice uv version command to change/bump the version number in the pyproject.toml, so I started thinking about how I'd also change the version in the __init__.py at the same time.
I asked ChatGPT what the best approach was and it suggested something quite different: don't write the value in __init__.py at all.
from importlib.metadata import version, PackageNotFoundError
try:
__version__ = version("package-name") # from pyproject.toml: project.name
except PackageNotFoundError:
__version__ = "0.0.0" # aka unknown versionI have since noticed that this was also the suggestion Adam Johnson had in the same thread.
One minor concern I have is whether this works in a cosmofy build, but that will be a separate exploration.