Add __version__ attribute to package

[nat-n]

This allows users to check which version of betterproto they're using be evaluating betterproto.__version__.

Includes a test to prevent the value from being incorrect in a release.

[abn]

I this really required? Is this information placed in the generated dataclasses and do we expect something along the lines of min version required for compatibility between runtime vs compile time versions? I just feel this adds more things to keep in sync if we do not have a clear use case. If someone really wanted wouldn't something like this be sufficient?

__import__('pkg_resources').get_distribution("betterproto").version

[nat-n]

I this really required? Is this information placed in the generated dataclasses and do we expect something along the lines of min version required for compatibility between runtime vs compile time versions? I just feel this adds more things to keep in sync if we do not have a clear use case. If someone really wanted wouldn't something like this be sufficient?

__import__('pkg_resources').get_distribution("betterproto").version

It's not really required. It's a convenience, and I think it's quite a common convention, to be able to do "import some_lib; some_lib.version".

Good to know that there's a general purpose solution. I suspect I'll have to check back here or google though next time I need it.

It adds an extra step to the process of updating the version, but at least the test means you can't forget.

[cetanu]

Personally I am 100% okay with the __import__('pkg_resources').get_distribution("betterproto").version implementation.

I don't know exactly what magic __import__() is doing though.

I use some variation of this in one of my repos:

from pkg_resources import get_distribution

__versionstr__ = get_distribution('betterproto').version
__version__ = tuple(int(i) for i in __versionstr__.split('.'))

I just find it easier to compare tuples...

I don't think it adds any harm or unnecessary overheads/maintenance to the library.

[cetanu]

I made changes to derive the version from the current distribution.

No point in not merging this. It gives users a shortcut that is very obviously seen from perusing the source.