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pathlib: Where does "self._flavour" comes from? (3.11 to 3.12 migration) #104921

Closed as not planned
Closed as not planned
pathlib: Where does "self._flavour" comes from? (3.11 to 3.12 migration)#104921
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3.12only security fixespendingThe issue will be closed if no feedback is providedstdlibStandard Library Python modules in the Lib/ directorytopic-pathlib

Description

@buhtz
buhtz
opened on May 25, 2023

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.

Activity

  1. hugovk
    added
    topic-pathlib
    stdlibStandard Library Python modules in the Lib/ directory
    3.12only security fixes
    on May 25, 2023

  2. hugovk commented on May 25, 2023

    @hugovk
    hugovk
    on May 25, 2023
    Member

    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.

  3. hugovk
    added
    pendingThe issue will be closed if no feedback is provided
    on May 25, 2023

  4. CAM-Gerlach commented on May 25, 2023

    @CAM-Gerlach
    CAM-Gerlach
    on May 25, 2023
    Member

    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.

  5. buhtz commented on May 25, 2023

    @buhtz
    buhtz
    on May 25, 2023
    Author

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

    From my point of view this Issue can be closed.

  6. hugovk
    closed this as not plannedon May 25, 2023

  7. barneygale commented on May 29, 2023

    @barneygale
    barneygale
    on May 29, 2023
    Contributor

    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

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