PEP 416: Add a builtin frozendict type

[vstinner]

BPO	14162
Nosy	@vstinner
Files	frozendict.patch frozendict_builtins.patch type_final.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 = None
closed_at = <Date 2012-03-26.20:22:50.839>
created_at = <Date 2012-02-29.18:05:03.872>
labels = ['interpreter-core', 'type-feature']
title = 'PEP 416: Add a builtin frozendict type'
updated_at = <Date 2012-03-26.20:22:50.837>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2012-03-26.20:22:50.837>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2012-03-26.20:22:50.839>
closer = 'vstinner'
components = ['Interpreter Core']
creation = <Date 2012-02-29.18:05:03.872>
creator = 'vstinner'
dependencies = []
files = ['24685', '24690', '24696']
hgrepos = []
issue_num = 14162
keywords = ['patch']
message_count = 5.0
messages = ['154655', '154656', '154670', '154690', '156866']
nosy_count = 1.0
nosy_names = ['vstinner']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue14162'
versions = ['Python 3.3']

Linked PRs

• gh-141510 Update mapping methods in abstract.c to accept frozendict #150692
• gh-141510 Document and test frozendict class matching behaviour #150799

[vstinner]

Patch to implement the PEP-416.

[vstinner]

There is no documentation update yet.

[vstinner]

frozendict_builtins.patch: make CPython supports frozendict for the __builtins__ mapping. It is an example of frozendict usage which helps my pysandbox project.

[vstinner]

Another frozendict usage example: freeze the dict of a new type if it contains __final__ in its namespace.

Example:

>>> class Classic:
... pass
... 
>>> Classic.attr=1
>>> class FinalizedType:
... __final__=True
... 
>>> FinalizedType.attr=1
(...)
TypeError: 'frozendict' object does not support item assignment

This patch is not part of the PEP-416 and is just a proof-of-concept.

[vstinner]

The PEP has been rejected. See issue bpo-14386 for a new mappingview type.