Drop restriction that meta.__prepare__() must return a dict (subclass)

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
python
Domain
compilers

Research direction

Start by reading the linked type-namespace-restriction.diff patch, then review the dependent issues bpo-17422 and bpo-31588 for related constraints and failure cases. Done means the restriction on meta.prepare() is addressed consistently and the relevant class-creation behavior is verified by tests.

Written by the indexing model from the issue text.

Description

interpreter-core type-feature
BPO 17421
Nosy @loewis, @ncoghlan, @vstinner, @durban, @ericsnowcurrently, @serhiy-storchaka, @cdonovick
Dependencies
  • bpo-17422: language reference should specify restrictions on class namespace
  • bpo-31588: SystemError in class creation in case of a metaclass with a bad prepare() method
    		•
    Files
  • type-namespace-restriction.diff
    		•

    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 = None
closed_at = None
created_at = <Date 2013-03-14.20:20:27.737>
labels = ['type-feature']
title = 'Drop restriction that meta.__prepare__() must return a dict (subclass)'
updated_at = <Date 2019-03-12.22:17:10.507>
user = 'https://github.com/ericsnowcurrently'

    bugs.python.org fields:

    activity = <Date 2019-03-12.22:17:10.507>
actor = 'donovick'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2013-03-14.20:20:27.737>
creator = 'eric.snow'
dependencies = ['17422', '31588']
files = ['29408']
hgrepos = []
issue_num = 17421
keywords = ['patch']
message_count = 6.0
messages = ['184187', '184203', '184206', '184309', '303022', '337814']
nosy_count = 7.0
nosy_names = ['loewis', 'ncoghlan', 'vstinner', 'daniel.urban', 'eric.snow', 'serhiy.storchaka', 'donovick']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue17421'
versions = ['Python 3.4']

    Dominant language
    Python
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