[issue21720] "TypeError: Item in ``from list'' not a string" message

Change by Serhiy Storchaka : -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: New changeset 2b5cbbb13c6c9138d04c3ca4eb7431f8c65d8e65 by Serhiy Storchaka in branch '3.6': [3.6] bpo-21720: Restore the Python 2.7 logic in handling a fromlist. (GH-4118) (#4128)

[issue21720] "TypeError: Item in ``from list'' not a string" message

Change by Serhiy Storchaka : -- pull_requests: +4093 stage: backport needed -> patch review ___ Python tracker ___

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: Given that the automated cherry-pick failed, I'd consider a 3.6 backport nice to have, but definitely not essential. My rationale for that is that "from __future__ import unicode_literals" makes it fairly easy to stumble over the 2.7

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: Is it worth to backport PR 4118 to 3.6? -- ___ Python tracker ___

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: New changeset 41c56940c6edf3ea169332a6b039b6c8796f0475 by Serhiy Storchaka in branch 'master': bpo-21720: Restore the Python 2.7 logic in handling a fromlist. (#4118)

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: Serhiy's PR avoids the cryptic BytesWarning on Py3 while minimising the overhead of the new typecheck, so I've closed Berker's PR in favour of that one (which now has approved reviews from both Brett and I, so Serhiy will merge it when he's

[issue21720] "TypeError: Item in ``from list'' not a string" message

Tal Einat added the comment: I understand that there is a workaround. I'm just thinking about the many existing large codebases where re-writing thousands of imports because of this is unlikely to be done, yet having somewhat longer process launch times would be

[issue21720] "TypeError: Item in ``from list'' not a string" message

Brett Cannon added the comment: As Nick said, if the overhead of an import statement is that critical, then you should NOT use the `from ... import ...` form at all and just stick with `import ...` and if necessary, bind local names to objects off of the final module or a

[issue21720] "TypeError: Item in ``from list'' not a string" message

Tal Einat added the comment: I can't say I agree that the performance here is practically insignificant. This will affect the startup time of Python process, and adding even 10% to that in some cases is significant. In some of the larger codebases I've worked on, even

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: There are other differences between Python 2.7 and Python 3. PR 4118 restores the Python 2.7 logic. It adds type checking, but its overhead is smaller. $ ./python -m timeit 'from encodings import aliases' 50 loops, best of

[issue21720] "TypeError: Item in ``from list'' not a string" message

Change by Serhiy Storchaka : -- pull_requests: +4088 ___ Python tracker ___ ___

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: The from import already is much slower than simple import: $ ./python -m timeit 'from encodings import aliases' 50 loops, best of 5: 475 nsec per loop $ ./python -m timeit 'import encodings.aliases as aliases' 100 loops,

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: I'm fine with the approach in the latest version of the PR - it does make "from x import y" slightly slower due to the extra error checking, but folks should be avoiding doing that in performance critical loops or functions anyway. It would

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: > I don't think the index in error message is needed. I'm fine with either format. It's ultimately up to Nick. Should I switch back to the 2.7 version? > Import is successful because the iterator was exhausted by "'*' in fromlist".

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: >>> __import__('encodings', fromlist=iter(('aliases', b'foobar'))) -- ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: I don't think the index in error message is needed. Unlike to str.join() which accepts arbitrary iterables of arbitrary names, the fromlist usually is a short tuple. Interesting, what happen if the fromlist is not a list or

[issue21720] "TypeError: Item in ``from list'' not a string" message

Change by Berker Peksag : -- pull_requests: +4083 stage: needs patch -> patch review ___ Python tracker ___

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: issue21720_python3.diff hasn't been applied. I'll convert my issue21720_python3.diff patch to a pull request. I like the format of Nick's "".join() example in msg278794. Here's my proposal for Python 3: f"Item {i} in 'from list'

[issue21720] "TypeError: Item in ``from list'' not a string" message

Change by Serhiy Storchaka : -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Ben Finney added the comment: On 23-Oct-2017, Serhiy Storchaka wrote: > Is it all with this issue? I accept Nick's reasoning: > As a general principle, we don't give value information in type > errors, since the error is structural rather than value based. as

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: Is it all with this issue? -- status: open -> pending ___ Python tracker ___

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: @Berker: the warning under "-bb" is a separate issue related to the handling of wildcard imports (_handle_fromlist searches for '*' and then pops it from a copy of the input list, replacing it with __all__ if that's defined) @Ben: As a general principle, we

[issue21720] "TypeError: Item in ``from list'' not a string" message

Ben Finney added the comment: On 16-Oct-2016, Roundup Robot wrote: > New changeset 7dd0910e8fbf by Berker Peksag in branch '2.7': > Issue #21720: Improve exception message when the type of fromlist is unicode > https://hg.python.org/cpython/rev/7dd0910e8fbf This is an improvement, but it still

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: Thanks for the reviews! I pushed the patch for 2.7. Nick, what do you think about the case Serhiy mentioned in msg278515? Should we fix it or is issue21720_python3.diff good to go? -- ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Roundup Robot added the comment: New changeset 7dd0910e8fbf by Berker Peksag in branch '2.7': Issue #21720: Improve exception message when the type of fromlist is unicode https://hg.python.org/cpython/rev/7dd0910e8fbf -- nosy: +python-dev ___ Python

[issue21720] "TypeError: Item in ``from list'' not a string" message

Ben Finney added the comment: On 12-Oct-2016, Nick Coghlan wrote: > In this case, I think just reporting the first failing item is fine, > and mentioning the type of that item in the error message is the > most useful additional information we can provide to make things > easier to debug. Yes;

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: Right, Python 2.7 import is what it is at this point - if folks want something more modern, they can take a look at importlib2 :) In this case, I think just reporting the first failing item is fine, and mentioning the type of that item in the error message is

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: Well, I find using a for loop is a bit verbose in this case :) In Python 3.2: >>> __import__('encodings', fromlist=[b'aliases']) Traceback (most recent call last): File "", line 1, in TypeError: Item in ``from list'' not a string BytesWarning is there since

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: > How about raising a TypeError if ``all(isinstance(l, str) for l in > fromlist)`` is False? That would make the exception message less clearer > since we can't include the "[...] not 'bytes'" part though. for l in fromlist: if not isinstance(l,

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: > Should we file a separate issue regarding the similarly vague error message > from hasattr() itself? +1 from me. It would be good to show users a user friendly message :) > BytesWarning: Comparison between bytes and string How about raising a TypeError if

[issue21720] "TypeError: Item in ``from list'' not a string" message

Serhiy Storchaka added the comment: If run Python 3 with -bb: >>> __import__('encodings', fromlist=[b'aliases']) Traceback (most recent call last): File "", line 1, in File "", line 1000, in _handle_fromlist BytesWarning: Comparison between bytes and string -- nosy:

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: Thanks Berker - looks good to me! Should we file a separate issue regarding the similarly vague error message from hasattr() itself? -- ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: Good catch, thanks Nick. Here's a Python 3 version of the patch. I excluded Python/importlib.h from the patch to make review easier. -- components: +Interpreter Core versions: +Python 3.5, Python 3.6, Python 3.7 Added file:

[issue21720] "TypeError: Item in ``from list'' not a string" message

Nick Coghlan added the comment: Berker's fix for Python 2.7 looks good to me. However, Python 3 has a comparably vague error message, it's just inverted to complain about bytes rather than unicode due to the change in the native str type: >>> __import__('encodings', fromlist=[b'aliases'])

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: Here's a patch to demonstrate what I meant in msg226047. Example from the REPL: >>> __import__('encodings', fromlist=[u'aliases']) Traceback (most recent call last): File "", line 1, in TypeError: Item in ``from list'' must be str, not unicode --

[issue21720] "TypeError: Item in ``from list'' not a string" message

Berker Peksag added the comment: I think we can classify this one as a usability bug and improve the exception message. -- nosy: +ncoghlan ___ Python tracker

[issue21720] "TypeError: Item in ``from list'' not a string" message

Tim Graham added the comment: As far as I can tell, this isn't an issue on Python 3. Can this be closed since Python 2 is only receiving bug fixes now? -- nosy: +Tim.Graham ___ Python tracker

[issue21720] TypeError: Item in ``from list'' not a string message

Ben Finney added the comment: Is there room for a better resolution: fix the API so that Unicode objects are accepted in the ‘fromlist’ items? -- nosy: +bignose ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720

[issue21720] TypeError: Item in ``from list'' not a string message

Changes by Ben Finney ben+pyt...@benfinney.id.au: ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue21720] TypeError: Item in ``from list'' not a string message

David Szotten added the comment: not sure i follow. we need a different message if e.g. an integer is passed in updated the patch to only run the unicode check for non-strings or do you have a suggestion for an error message that works nicely in both cases? -- Added file:

[issue21720] TypeError: Item in ``from list'' not a string message

Julian Gindi added the comment: I'm trying to replicate this issue. I do not get an error when I run ``` __import__('datetime', fromlist=[u'datetime']) ``` any more information you could provide to help move this issue forward? -- nosy: +Julian.Gindi

[issue21720] TypeError: Item in ``from list'' not a string message

David Szotten added the comment: after some trial and error it only appears to break for 3rd party packages (all 20 or so i happened to have installed), whereas everything i tried importing from the standard library worked fine ``` __import__('requests.', fromlist=[u'get']) Traceback (most

[issue21720] TypeError: Item in ``from list'' not a string message

Julian Gindi added the comment: Interesting...I'll try to dig in and see what's going on. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___

[issue21720] TypeError: Item in ``from list'' not a string message

David Szotten added the comment: first ever patch to python, so advice on the patch would be appreciated found an example in the stdlib that triggers bug (used in test): `__import__('encodings', fromlist=[u'aliases'])` -- keywords: +patch Added file:

[issue21720] TypeError: Item in ``from list'' not a string message

Berker Peksag added the comment: Thanks for the patch, David! +def test_fromlist_error_messages(self): +# Test for issue #21720: fromlist unicode error messages +try: +__import__('encodings', fromlist=[u'aliases']) +except TypeError as exc: +

[issue21720] TypeError: Item in ``from list'' not a string message

Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- assignee: - rhettinger nosy: +rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___

[issue21720] TypeError: Item in ``from list'' not a string message

Changes by Raymond Hettinger raymond.hettin...@gmail.com: -- assignee: rhettinger - ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___ ___

[issue21720] TypeError: Item in ``from list'' not a string message

Changes by Berker Peksag berker.pek...@gmail.com: -- nosy: +berker.peksag ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___ ___

[issue21720] TypeError: Item in ``from list'' not a string message

Ezio Melotti added the comment: Do you want to propose a patch? I think the standard message in these cases is along the lines of TypeError: fromlist argument X must be str, not unicode -- keywords: +easy nosy: +ezio.melotti stage: - needs patch

[issue21720] TypeError: Item in ``from list'' not a string message

New submission from David Szotten: ``` __import__('fabric.', fromlist=[u'api']) Traceback (most recent call last): File stdin, line 1, in module ``` accidentally ended up with something like this via some module that was using `unicode_literals`. stumped me for a second until i realised

[issue21720] TypeError: Item in ``from list'' not a string message

Changes by Berker Peksag berker.pek...@gmail.com: -- nosy: +brett.cannon, eric.snow ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue21720 ___ ___