pathlib: Where does "self._flavour" comes from? (3.11 to 3.12 migration)

[buhtz]

This question is related to Python 3.12.

cpython/Lib/pathlib.py

Line 319 in 278030a

self._raw_path = self._flavour.join(*paths)

This is the first occurrence of self._flavour in pathlib.py. I don't see where this object is set. I can't find the string self._flavour = somewhere in the repo. I'm confused.

Background:
I try to figuring out why pathlib._Flavour.parse_parts() (and the whole class) was removed from Python 3.11 to 3.12. I can not see this in the CHANGELOG. And I'm not skilled enough with git to find the related commit.

[hugovk]

Thank you for testing the beta!

pathlib._Flavour was removed in #31691.

The linked issues are gh-68320, gh-88302. From the latter:

Following bpo-39899, bpo-43757 and bpo-43012, pathlib._Flavour and its subclasses are looking a bit pointless.

The implementations of is_reserved() and make_uri() (~as_uri()) can be readily moved to into PurePosixPath and PureWindowsPath, which removes some indirection. This follows the pattern of OS-specific stuff in PosixPath and WindowsPath.

The remaining methods, such as splitroot(), can be pulled into Pure*Path with an underscore prefix.

I'm generally a believer in composition over inheritance, but in this case _Flavour seems too small and too similar to PurePath to separate out into 3 extra classes.

There should be no impact on public APIs or performance.

I expect there was no CHANGELOG entry because the undescores indicate these are private and not part of the public API, and pyfakefs will need refactoring to use something else.

cc @barneygale

---

PS I did git log -S _Flavour Lib/pathlib.py to find the most recent commit mentioning the class, including deletes.

[CAM-Gerlach]

Also, just to note, _parse_parts itself (likewise still a private method) was replaced with _parse_path in PR #102789 , to address issues #76846 and #85281 . Presumably, the intention is to properly subclass Path rather than relying on private internal-only members, though @barneygale is the expert and can likely advise you what's best for your use case much more specifically.

[buhtz]

Awesome! Great!
Thanks a lot for helping and explaining. I learned a lot.

From my point of view this Issue can be closed.

[barneygale]

For posterity, the motivation/explanation for the removal of the flavour classes can be found here: https://discuss.python.org/t/make-pathlib-extensible/3428/42