python / python/cpython

WeakKeyDictionary/Mapping doesn't call __missing__

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3.7 (EOL) stdlib type-feature
Dominant language
Python
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Description

BPO 31254
Nosy @rhettinger, @pitrou, @njsmith, @asqui

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 2017-08-22.07:31:12.218>
labels = ['3.7', 'type-feature', 'library']
title = "WeakKeyDictionary/Mapping doesn't call __missing__"
updated_at = <Date 2020-06-07.17:16:01.585>
user = 'https://github.com/anntzer'

bugs.python.org fields:

activity = <Date 2020-06-07.17:16:01.585>
actor = 'Antony.Lee'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-08-22.07:31:12.218>
creator = 'Antony.Lee'
dependencies = []
files = []
hgrepos = []
issue_num = 31254
keywords = ['patch']
message_count = 14.0
messages = ['300671', '300739', '300789', '300794', '300800', '300810', '300816', '300817', '300818', '300821', '300826', '300831', '300848', '370697']
nosy_count = 4.0
nosy_names = ['rhettinger', 'pitrou', 'njs', 'dfortunov']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue31254'
versions = ['Python 3.7']

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue identifies WeakKeyDictionary/Mapping and the desired missing behavior, but names no implementation file or test. Begin by locating those standard-library implementations and existing mapping tests; done means the missing-key behavior is covered and the relevant tests pass.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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