Inconsistency between b32decode() documentation, docstring and code

[serhiy-storchaka]

BPO	18011
Nosy	@gvanrossum, @warsaw, @bitdancer, @ethanfurman, @serhiy-storchaka
Files	b32decode_exception.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 2013-05-28.12:36:41.213>
created_at = <Date 2013-05-19.08:19:09.621>
labels = ['type-bug', 'library', 'docs']
title = 'Inconsistency between b32decode() documentation, docstring and code'
updated_at = <Date 2014-01-08.23:02:51.711>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2014-01-08.23:02:51.711>
actor = 'r.david.murray'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2013-05-28.12:36:41.213>
closer = 'serhiy.storchaka'
components = ['Documentation', 'Library (Lib)']
creation = <Date 2013-05-19.08:19:09.621>
creator = 'serhiy.storchaka'
dependencies = []
files = ['30310']
hgrepos = []
issue_num = 18011
keywords = ['patch']
message_count = 8.0
messages = ['189571', '189576', '189901', '190201', '190202', '207708', '207710', '207711']
nosy_count = 7.0
nosy_names = ['gvanrossum', 'barry', 'r.david.murray', 'docs@python', 'ethan.furman', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue18011'
versions = ['Python 3.3', 'Python 3.4']

[serhiy-storchaka]

b32decode() documentation says: "A TypeError is raised if s were incorrectly padded or if there are non-alphabet characters present in the string."

b32decode() docstring says: "binascii.Error is raised if the input is incorrectly padded or if there are non-alphabet characters present in the input."

Actually binascii.Error (which is a ValueError subtype) is raised if the input is incorrectly padded and TypeError is raised if there are non-alphabet characters present in the input.

At least 2 of 3 (documentation, docstring and implementation) should be corrected.

Base32 support was originally added in 3cc0d8fd4e2b (TypeError was used everywhere) and then modified in eb45f85c4c79 (TypeError was partially changed to binascii.Error).

[serhiy-storchaka]

Here is a patch which changes TypeError to binascii.Error in b32decode() and fixes the documentation and tests.

[serhiy-storchaka]

Are there any objections?

[python-dev]

New changeset 0b9bcb2ac145 by Serhiy Storchaka in branch '3.3':
Issue bpo-18011: base64.b32decode() now raises a binascii.Error if there are
http://hg.python.org/cpython/rev/0b9bcb2ac145

New changeset 7446f53ba2d2 by Serhiy Storchaka in branch 'default':
Issue bpo-18011: base64.b32decode() now raises a binascii.Error if there are
http://hg.python.org/cpython/rev/7446f53ba2d2

[python-dev]

New changeset 29a823f31465 by Serhiy Storchaka in branch 'default':
Issue bpo-18011: Silence an unrelated noise introduced in changeset 1b5ef05d6ced.
http://hg.python.org/cpython/rev/29a823f31465

[bitdancer]

For future reference, because this patch changed the type of an error, it should not have been applied to a maintenance release (3.3). Since the change has already been released in 3.3.3, it is now better not to revert it.

[serhiy-storchaka]

This is not incompatible change because b32decode() already raised this type of an error. Third-party code which use b32decode() was either incorrect (if it catches only TypeError or binascii.Error when any of them could raised) or is not broken by this change.

[bitdancer]

But code could be catching TypeError specifically looking for the alphabet error, since that is how it was documented.