ENH: Allow ctypeslib.load_library to take any path-like object

[BvB93]

This PR allows ctypeslib.load_library() take take any path-like object,
which includes the likes of strings, bytes and any object implementing the __fspath__ protocol.

[BvB93]

Note that the try / except clause is redundant due to the pytest fixture:

numpy/numpy/tests/test_ctypeslib.py

Lines 35 to 39 in a9edc04

	@pytest.mark.skipif(ctypes is None,
	reason="ctypes not available in this python")
	@pytest.mark.skipif(sys.platform == 'cygwin',
	reason="Known to fail on cygwin")
	class TestLoadLibrary:

[eric-wieser]

Are paths with / actually allowed here? If not, this looks like it should remain a str

[BvB93]

It seems to be, yes.
What happens when defining libpath is, roughly speaking, calling os.path.join on loader_path and libname the input parameters.

numpy/numpy/ctypeslib.py

Lines 144 to 148 in 4afd82d

	for ln in libname_ext:
	libpath = os.path.join(libdir, ln)
	if os.path.exists(libpath):
	try:
	return ctypes.cdll[libpath]

[eric-wieser]

Hmm, to me that implies the path component should always be in loader_path, and libname should always be a string.

[BvB93]

Perhaps, though os.path.join is not required to join a path and a file name;
the joining of two paths is also perfectly acceptable.

In [1]: import os

In [2]: os.path.join('a/b/c/', 'd/e/f')
Out[2]: 'a/b/c/d/e/f'

Besides, why should it remain a string if a / is not allowed?
The likes of pathlib.Path are just generally useful objects, regardless of whether it is used to represent a path- or file-name.

[charris]

Needs a release note.

[BvB93]

Needs a release note.

See d690cf6.

[charris]

@eric-wieser Look good to you?

[charris]

close/reopen

[charris]

@eric-wieser Ping.

[charris]

Thanks Bas.