Documentation on `GenericAlias` objects and `__class_getitem__` could be improved

[AlexWaygood]

BPO	45680
Nosy	@gvanrossum, @ambv, @JelleZijlstra, @miss-islington, @Fidget-Spinner, @AlexWaygood
PRs	bpo-45680: Clarify documentation on GenericAlias objects #29335 bpo-45680: typing docs: improve links to docs on GenericAlias/__class_getitem__ #29387 [doc] bpo-45680: Improve glossary entry for generic types #29388 [doc] bpo-45680: Disambiguate __getitem__ and __class_getitem__ in the data model. #29389 [3.10] bpo-45680: typing docs: improve links to docs on GenericAlias/__class_getitem__ (GH-29387) #29399 [3.9] bpo-45680: typing docs: improve links to docs on GenericAlias/__class_getitem__ (GH-29387) #29400 [3.10] [doc] bpo-45680: Improve glossary entry for generic types (GH-29388) #29447 [3.9] [doc] bpo-45680: Improve glossary entry for generic types (GH-29388) #29448 bpo-45680: Improve docs on subscriptions w.r.t. GenericAlias objects #29479 [3.9] [doc] bpo-45680: Disambiguate __getitem__ and __class_getitem__ in the data model (GH-29389) #29619 [3.10] [doc] bpo-45680: Disambiguate __getitem__ and __class_getitem__ in the data model (GH-29389) #29620 [3.10] bpo-45680: Clarify documentation on GenericAlias objects (GH-29335) #30688 [3.9] bpo-45680: Clarify documentation on GenericAlias objects (GH-29335) #30689 bpo-45680: Minor formatting fix in stdtypes.rst #30690 [3.10] bpo-45680: Improve docs on subscriptions w.r.t. GenericAlias objects (GH-29479) #31743 [3.9] bpo-45680: Improve docs on subscriptions w.r.t. GenericAlias objects (GH-29479) #31744

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

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2022-03-08.03:59:23.108>
created_at = <Date 2021-10-30.20:21:29.476>
labels = ['3.11', 'type-bug', '3.9', '3.10', 'docs']
title = 'Documentation on `GenericAlias` objects and `__class_getitem__` could be improved'
updated_at = <Date 2022-03-08.07:55:01.501>
user = 'https://github.com/AlexWaygood'

bugs.python.org fields:

activity = <Date 2022-03-08.07:55:01.501>
actor = 'AlexWaygood'
assignee = 'docs@python'
closed = True
closed_date = <Date 2022-03-08.03:59:23.108>
closer = 'JelleZijlstra'
components = ['Documentation']
creation = <Date 2021-10-30.20:21:29.476>
creator = 'AlexWaygood'
dependencies = []
files = []
hgrepos = []
issue_num = 45680
keywords = ['patch']
message_count = 24.0
messages = ['405384', '405385', '405662', '405664', '405665', '405871', '405876', '405878', '406542', '406557', '406558', '410954', '410956', '410959', '410966', '410967', '410969', '411489', '411490', '414712', '414714', '414718', '414719', '414730']
nosy_count = 7.0
nosy_names = ['gvanrossum', 'docs@python', 'lukasz.langa', 'JelleZijlstra', 'miss-islington', 'kj', 'AlexWaygood']
pr_nums = ['29335', '29387', '29388', '29389', '29399', '29400', '29447', '29448', '29479', '29619', '29620', '30688', '30689', '30690', '31743', '31744']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45680'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[AlexWaygood]

The documentation on GenericAlias objects implies at multiple points that only container classes can implement __class_getitem__, and goes into very little detail about what it means for a non-container class to be parameterized.

[AlexWaygood]

This issue is related, but distinct, to previous issue https://bugs.python.org/issue42280.