For instance:# `a` is an empty directory, aPEP 420 namespace package>>> import importlib.util>>> importlib.util.find_spec('a')ModuleSpec(name='a', loader=None, origin='namespace', submodule_search_locations=_NamespacePath(['/tmp/x/a']))https://docs.python.org/3/library/importlib.html#importlib.machinery.ModuleSpec.origin> ...  Normally “origin” should be set, but it may be None (the default) which indicates it is unspecified (e.g. for namespace packages).above the `origin` is `'namespace'`https://docs.python.org/3/library/importlib.html#importlib.machinery.ModuleSpec.submodule_search_locations> List of strings for where to find submodules, if a package (None otherwise).However the `_NamespacePath` object above is not indexable:>>> x = importlib.util.find_spec('a').submodule_search_locations>>> x[0]Traceback (most recent call last):  File "<stdin>", line 1, in <module>TypeError: '_NamespacePath' object does not support indexingI can work around however with:>>> next(iter(x))'/tmp/x/a'======================so I guess a few things can/should come out of this:- Document the `'namespace'` origin- Document that `submodule_search_paths` is a Sized[str] instead- Add `__getitem__` to `_NamespacePath` such that it implements the full `Sized` protocol

Hmmm, it appears this was changed in python3.7 to have `None` for the origin instead of `'namespace'` -- however the `submodule_search_locations` is still not indexable:>>> importlib.util.find_spec('a')ModuleSpec(name='a', loader=None, submodule_search_locations=_NamespacePath(['/tmp/x/a']))>>> importlib.util.find_spec('a').origin>>> spec = importlib.util.find_spec('a')>>> spec.submodule_search_locations_NamespacePath(['/tmp/x/a'])>>> spec.submodule_search_locations[0]Traceback (most recent call last):  File "<stdin>", line 1, in <module>TypeError: '_NamespacePath' object does not support indexing

See also#35673.

Anyone have an opinion about the __getitem__ proposal? I'm fine with it but I wanted to make sure other import + namespace folks don't disagree.

+1

New changesetab9b31f94737895f0121f26ba3ad718ebbc24fe1 by Miss Islington (bot) (Anthony Sottile) in branch 'master':bpo-35843: Implement __getitem__ for _NamespacePath (GH-11690)https://github.com/python/cpython/commit/ab9b31f94737895f0121f26ba3ad718ebbc24fe1