Issue 20639: pathlib.PurePath.with_suffix() does not allow removing the suffix (original) (raw)

The changeset ef2b2ddd27c8 restricted the argument of Path.with_suffix() too much, and caused some strange behavior.

Case 1: removing suffix completely is disallowed now. The following code worked before the fix:

pathlib.PurePath('a', 'b.c').with_suffix('') PurePosixPath('a/b')

but now fails with ValueError:

pathlib.PurePath('a', 'b.c').with_suffix('') Traceback (most recent call last): File "", line 1, in File "/home/july/source/python/Lib/pathlib.py", line 760, in with_suffix raise ValueError("Invalid suffix %r" % (suffix)) ValueError: Invalid suffix ''

It was the only one obvious way of removing the suffix, and I think it should remain so. (BTW: There is a XXX note in the code questioning if Path.with_suffix(None) should remove the suffix.)

Case 2: while the output is now always a correct Path, the suffix can still contain separator. The following code produced incorrect path before the fix:

pathlib.PurePath('a', 'b.c').with_suffix('./.s/.') PurePosixPath('a/b./.s/.') _.parts ('a', 'b./.s/.')

Now, the produced path is correct, but the code itself is still allowed:

pathlib.PurePath('a', 'b.c').with_suffix('./.s/.') PurePosixPath('a/b.s')

while I would expect it to fail with ValueError.

Attached: proposed test patch.