Provide a way to instantiate a version quickly when the parsed content is known

[RonnyPfannschmidt]

users of setuptools_scm like to expose their version variables, unfortunately importing Version, loading it to compile the regex and parsing the version string is often a cost they don't want to pay,
so the safe default has to stay version strings and/or mixed type version tuples

i'd like to be able to expose Version instances there at a reasonable cost

for that to happen i believe whats needed is

a) a mypyc'd or cythonized version module thats practically importing at no cost
b) a way to instantiate a version without incurring the regex compile + parse cost

it may help to migrate to hatch while at it as it has tools to handle mypyc and cibuildwheel

[brettcannon]

We are purposefully a pure Python project for bootstrapping purposes, so shifting to something that requires C code isn't an option (i.e. we have to be able to be vendored into pip which needs to be able to be shipped as a zipapp).

As for providing a class that skips the string parse, I would be okay with combining _BaseVersion and Version sans string parsing into a BaseVersion class and having Version provide the parsing support. The other option is to make the version argument to Version.__init__() optional and expose keyword only arguments for manually specifying the various parts of a version.

Hindsight suggest it would have been good to have a classmethod instead of always parsing (although we have version.parse()), but this API has been around for too long at this point to bother deprecating.

[uranusjr]

I think what was implied by the Mypyc/Cython suggestion is for the project to stay Python-only, but publish additional wheels for those pre-compiled code. Projects that want a pure Python version can still use the none-any wheel.

[RonnyPfannschmidt]

Yes, im. Very well aware of the vendoring needs, however those are not necessarily in conflict with providing speed up wheels when using tools like mypyc

As for providing a non parsing api, I'll experiment with providing one

[brettcannon]

those are not necessarily in conflict with providing speed up wheels when using tools like mypyc

True, but it does increase maintenance burden and I don't know if it's worth it in this case. Plus I come from the camp of preferring to try and speed up Python or be okay with the performance than work around it with more native code.

As for providing a non parsing api, I'll experiment with providing one

👍