Feature or enhancement

Provide a way of checking whether a user subclass ofpathlib.PurePath andPath uses POSIX or Windows semantics

The Problem

Now that#68320 is resolved, users can subclasspathlib.PurePath andPath directly:

importpathlibclassMyPath(pathlib.Path):passpath=MyPath('foo')

However, there's no (public) procedure to detect whether an instance ofMyPath uses POSIX or Windows semantics.

A non-public way of doing it:

path._flavourisposixpath# Check whether the path object uses POSIX semanticspath._flavourisntpath# Check whether the path uses Windows semanticspath._flavourisos.path# Check whether the path uses the current OS's semantics

Note that checkingisinstance(path, PurePosixPath) (etc) won't work, as user subclasses ofPurePath andPath do not have the POSIX- and Windows-specific subclasses in their class hierarchy.

The Proposal

Make the_flavour attribute public; document it. Possible names:

• flavour (simply remove the underscore)
• pathmod (used internally in older pathlib versions)
• module (used in the longstanding thirdpartypath package)

Alternatives

We could make thePurePosixPath andPureWindowsPath classes 'protocols', which supportisinstance() checks even when the passed object isn't a conventional subclass. But:

1. The implementation will be more complex
2. It could open a can of worms about whetherPurePosixPath andPureWindowsPath should be proper protocols, and not directly instantiable.

A further alternative would be to add anis_posix() method, which gels pretty nicely with the existingis_*() andas_posix() methods.

Linked PRs

• GH-100502: Addpathlib.PurePath.pathmod attribute #106533