Bare except: usages in turtle.py

[JelleZijlstra]

BPO	27238
Nosy	@brettcannon, @terryjreedy, @vadmium, @serhiy-storchaka, @JelleZijlstra
Files	issue27238.patch issue27238-cr.patch: revised patch

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

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2016-06-14.19:55:39.216>
created_at = <Date 2016-06-06.00:38:06.281>
labels = ['type-bug', 'library']
title = 'Bare except: usages in turtle.py'
updated_at = <Date 2016-06-14.19:55:39.215>
user = 'https://github.com/JelleZijlstra'

bugs.python.org fields:

activity = <Date 2016-06-14.19:55:39.215>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-06-14.19:55:39.216>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2016-06-06.00:38:06.281>
creator = 'JelleZijlstra'
dependencies = []
files = ['43258', '43299']
hgrepos = []
issue_num = 27238
keywords = ['patch']
message_count = 11.0
messages = ['267493', '267528', '267556', '267562', '267570', '267592', '267779', '268167', '268583', '268584', '268585']
nosy_count = 6.0
nosy_names = ['brett.cannon', 'terry.reedy', 'python-dev', 'martin.panter', 'serhiy.storchaka', 'JelleZijlstra']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue27238'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6']

[JelleZijlstra]

Will add a patch

[JelleZijlstra]

This patch removes all usages of "except:" in turtle.py. The tests in test_turtle.py and turtle.rst still work.

[serhiy-storchaka]

Brett, can __file__ of imported/executed module be None, bytes or absent in 3.6? Can it be non-str?

[brettcannon]

__file__ could be None if __spec__.origin is None. The import machinery doesn't introspect on __file__ for anything, so it won't break import if __file__ has alternative values. In general, though, normal imports will set __file__ to a string.

[vadmium]

The documentation says __file__ can be missing. It is missing for builtin modules (e.g. sys) and frozen modules (e.g. __hello__).

[serhiy-storchaka]

Thanks Brett and Martin.

Jelle, I think it would be safer to use "except Exception" here. "except (TypeError, ValueError):" is not enough.

[JelleZijlstra]

Thanks for the review and comments. This patch addresses your comments and changes the __file__-related one to catch Exception.

[terryjreedy]

Add a comment to indicate that bare exception is intentional and briefly why.

[serhiy-storchaka]

LGTM.

There is no case for bare except here. Actually it is a bug, since (in this file) a bare except can swallow KeyboardInterrupt.