Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Broken encoding modules are silently skipped. #72192

Closed
ericsnowcurrently opened this issue Sep 7, 2016 · 7 comments
Closed

Broken encoding modules are silently skipped. #72192

ericsnowcurrently opened this issue Sep 7, 2016 · 7 comments
Assignees
@zooba
Labels
interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error

Comments

@ericsnowcurrently
Copy link
Member

BPO 28005
Nosy @malemburg, @ericsnowcurrently, @zooba

Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

Show more details

GitHub fields:

assignee = 'https://github.com/zooba'
closed_at = <Date 2016-09-09.15:59:19.672>
created_at = <Date 2016-09-07.18:17:08.667>
labels = ['interpreter-core', 'type-bug', 'invalid']
title = 'Broken encoding modules are silently skipped.'
updated_at = <Date 2016-09-09.15:59:19.670>
user = 'https://github.com/ericsnowcurrently'

bugs.python.org fields:

activity = <Date 2016-09-09.15:59:19.670>
actor = 'steve.dower'
assignee = 'steve.dower'
closed = True
closed_date = <Date 2016-09-09.15:59:19.672>
closer = 'steve.dower'
components = ['Interpreter Core']
creation = <Date 2016-09-07.18:17:08.667>
creator = 'eric.snow'
dependencies = []
files = []
hgrepos = []
issue_num = 28005
keywords = []
message_count = 7.0
messages = ['274856', '274933', '274978', '274983', '275011', '275279', '275325']
nosy_count = 5.0
nosy_names = ['lemburg', 'syeberman', 'python-dev', 'eric.snow', 'steve.dower']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue28005'
versions = ['Python 3.6']
@ericsnowcurrently
Copy link
Member Author

In Lib/encodings/init.py, search_function() looks up an encoding by name. It loads the encoding by importing the corresponding module in the encodings package. If there's an ImportError while importing that module then the encoding gets silently ignored. I noticed this while working on issue bpo-16384.

While I don't have any direct interest in the matter, I expect that it would be more useful to users if we issued a warning or some other printed message when an encoding is ignored.

@ericsnowcurrently ericsnowcurrently added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error labels Sep 7, 2016
@python-dev
Copy link
Mannequin

python-dev mannequin commented Sep 8, 2016

New changeset 2b2e7b39bb68 by Steve Dower in branch 'default':
Issue bpo-28005: Allow ImportErrors in encoding implementation to propagate.
https://hg.python.org/cpython/rev/2b2e7b39bb68

@zooba zooba closed this as completed Sep 8, 2016
@zooba zooba self-assigned this Sep 8, 2016
@malemburg
Copy link
Member

Steve, this is not a correct patch. The purpose of skipping ImportErrors is to give other search functions a chance to find and provide a working codec. Your patch causes this to break.

@malemburg malemburg reopened this Sep 8, 2016
@malemburg
Copy link
Member

Thinking about this some, we could go ahead and document somewhere that if a codec wants to tell the search function that it cannot work due to some missing dependency, it will have to raise an ImportError from the codec module level (instead of just lettering ImportError bubble up), possibly reraising the error to assure this.

@zooba
Copy link
Member

zooba commented Sep 8, 2016

Is it deliberate that inner import errors should be treated as if the codec is missing? Another search function isn't going to help in that case unless it finds the same encoding in another place. I didn't see any evidence of that, and apparently neither did Eric (but I was bitten by a misspelt import within my new encodings/oem.py giving a confusing message).

I don't think any encoding modules in the stdlib should fail to import. This change ensures that we hear about it if they do fail.

@malemburg
Copy link
Member

Yes, that's intended. See e.g. the mbcs codec.

If a search function gets an ImportError, it interprets this as "codec is not available/working", and then gives other search functions a chance to find a working one.

@zooba
Copy link
Member

zooba commented Sep 9, 2016

I reverted the change but wrote the wrong issue number. Also added a comment so the next person to encounter this realises it is the correct behaviour.

New changeset 4e80a157ea66 by Steve Dower in branch 'default':
Revert bpo-27959: ImportError within an encoding module should also skip the encoding
https://hg.python.org/cpython/rev/4e80a157ea66

@zooba zooba closed this as completed Sep 9, 2016
@zooba zooba added the invalid label Sep 9, 2016
@ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees

@zooba zooba

Labels
interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
3 participants
@ericsnowcurrently @zooba @malemburg