PEP0435 (enums) -- there is no standard on enum item letters case

[socketpair]

BPO	40721
Nosy	@warsaw, @ethanfurman, @socketpair, @miss-islington, @DahlitzFlorian, @remilapeyre
PRs	bpo-40721: add note about enum member name case #22231 [3.8] bpo-40721: add note about enum member name case (GH-22231) #22247 [3.9] bpo-40721: add note about enum member name case (GH-22231) #22248

^{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 2020-09-14.20:51:34.700>
created_at = <Date 2020-05-21.21:42:56.454>
labels = ['3.8', '3.9', '3.10', 'docs']
title = 'PEP0435 (enums) -- there is no standard on enum item letters case'
updated_at = <Date 2020-09-14.20:51:34.699>
user = 'https://github.com/socketpair'

bugs.python.org fields:

activity = <Date 2020-09-14.20:51:34.699>
actor = 'ethan.furman'
assignee = 'docs@python'
closed = True
closed_date = <Date 2020-09-14.20:51:34.700>
closer = 'ethan.furman'
components = ['Documentation']
creation = <Date 2020-05-21.21:42:56.454>
creator = 'socketpair'
dependencies = []
files = []
hgrepos = []
issue_num = 40721
keywords = ['patch']
message_count = 8.0
messages = ['369544', '369545', '369546', '369565', '376855', '376901', '376902', '376903']
nosy_count = 8.0
nosy_names = ['barry', 'eli.bendersky', 'docs@python', 'ethan.furman', 'socketpair', 'miss-islington', 'DahlitzFlorian', 'remi.lapeyre']
pr_nums = ['22231', '22247', '22248']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue40721'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[socketpair]

Example from PEP-0435:

(https://www.python.org/dev/peps/pep-0435)

>>> from enum import Enum
>>> class Color(Enum):
...     red = 1
...     green = 2
...     blue = 3

Example from Python documentation:

(https://docs.python.org/3/library/enum.html)

>>> from enum import Enum
>>> class Color(Enum):
...     RED = 1
...     GREEN = 2
...     BLUE = 3
...

So, what are the rules for naming enum members?
CamelCase ? snake_case ? ALL_CAPS ?

Someone should explain how should we format sources. So various linters may check for that.

[socketpair]

FYI: PEP-8 does not mention enums.

[remilapeyre]

There is no official way, you can find both in the Python tree: all caps at https://github.com/python/cpython/blob/master/Lib/ast.py#L615-L636 and snake case at https://github.com/python/cpython/blob/master/Lib/uuid.py#L76-L79.

I think it's common to use all caps for those that are used as flags (i.e. where each value is a power of 2 and that may be combined using bigs operations) but there is no one true way that you can enforced, it depends on the context.

Also, note that PEP-8 covers the code of Python, it's not a rule that must be blindly applied to all Python code and that you may ignore it for various reasons: https://www.python.org/dev/peps/pep-0008/#a-foolish-consistency-is-the-hobgoblin-of-little-minds.

[DahlitzFlorian]

Should we add a note that there is no preferred way of naming enum members and provide a few examples or define some naming conventions?

[ethanfurman]

For Python code at least, Guido has proclaimed:

https://mail.python.org/pipermail/python-ideas/2016-September/042340.html

I recommend naming all enums UPPER_CASE. They're constants (within a
namespace) and that's the rule for constants. It's helpful for the
reader of the code to realize what they are when passed around -- they
have a similar status to literal constants, you know they stand for a
unique value and not for some computed quantity.