Description

barneygale

opened on Apr 13, 2023

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Since 6716254, attempting to create a pathlib.PurePath or Path object with mixed str and bytes arguments raises a TypeError (yay!) with a misleading message (booo!):

>>> import pathlib
>>> pathlib.Path('foo', b'bar')
TypeError: Can't mix strings and bytes in path components

This message implies that bytes are supported, as long as we don't mix them with strings. And yet when we try that:

>>> pathlib.Path(b'foo', b'bar')
TypeError: argument should be a str or an os.PathLike object where __fspath__ returns a str, not 'bytes'

This message is better, and should be used in the former case.

Linked PRs

• GH-103525: Improve exception message from pathlib.PurePath() #103526

Activity

1. barneygale

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   3.12only security fixesonly security fixes

   topic-pathlib

   on Apr 13, 2023
2. barneygale

   added 2 commits that reference this issue on Apr 13, 2023

   pythonGH-103525: Improve exception message from `pathlib.PurePath()`

   7804b2e

   pythonGH-103525: Improve exception message from `pathlib.PurePath()`

   6c1131e
3. terryjreedy commented on Apr 13, 2023

   

   terryjreedy

   on Apr 13, 2023

   Member

   More actions

   The following

   >>> pathlib.Path('foo', 1)
   Traceback (most recent call last):
     File "C:\Programs\Python312\Lib\pathlib.py", line 703, in __init__
       super().__init__(*args)
     File "C:\Programs\Python312\Lib\pathlib.py", line 279, in __init__
       path = self._flavour.join(*args)
     File "<frozen ntpath>", line 149, in join
     File "<frozen genericpath>", line 164, in _check_arg_types
   TypeError: join() argument must be str, bytes, or os.PathLike object, not 'int'

   raises a message again implying that bytes would be accepted. It would be nicer if this also got the improved message about Path args.
   ADDED: When the new code calls os.fspath(1), the message will be

   expected str, bytes or os.PathLike object, not int
   which still implies that bytes are accepted.
4. barneygale commented on Apr 13, 2023

   

   barneygale

   on Apr 13, 2023

   ContributorAuthor

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   That's possible to fix, but it involves either capturing and re-raising the TypeError, or basically re-implementing os.fspath(). This code is pretty performance-sensitive so I don't feel great about it.

   Another option would be to add a string_only argument to os.fspath() that rejects bytes and raises an appropriate exception.
5. barneygale commented on Apr 13, 2023

   

   barneygale

   on Apr 13, 2023

   ContributorAuthor

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   That's possible to fix, but it involves either capturing and re-raising the TypeError, or basically re-implementing os.fspath(). This code is pretty performance-sensitive so I don't feel great about it

   ^ nevermind, I'm wrong. Thanks for the suggestion on the PR!
6. barneygale

   added 2 commits that reference this issue on Apr 29, 2023

   Merge branch 'main' into pythongh-103525-purepath-mix-str-bytes-typee…

   6d2697c

   GH-103525: Improve exception message from `pathlib.PurePath()` (GH-10…

   8611e7b
7. barneygale commented on May 2, 2023

   

   barneygale

   on May 2, 2023

   ContributorAuthor

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   Fixed in #103526 / 8611e7b. Not backported as the bug only affects 3.12.
8. barneygale

   closed this as completedon May 2, 2023
9. carljm

   added 2 commits that reference this issue on May 2, 2023

   Merge branch 'main' into inlinecomp2

   0727d6f

   Merge branch 'main' into cached_property_docs

   b9c39e3

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