How to allow a class attribute to be accessible from the module global context in Python?

Question

I defined an enum class and would like to be able to use its attributes without need to access it through class name. I mean:

class MyEnum:
    ONE = 1
    TWO = 2
    ...

if MyEnum.ONE == 1:
    "Typic use"
if TWO == 2:
    "My desire"

Is there a way to do this?

In my specific context, I'm calculating points externality of a window through Cohen–Sutherland algorithm, so I have the following code:

class Externality:
    INSIDE = 0
    LEFT = 1
    RIGTH = 2
    BELLOW = 4
    ABOVE = 8

# And at some point:
((x, y), externality) = actual

if not Externality.INSIDE in externality:
    del cohen_sutherland_list[0]

So, the needed of express Enum's name to access its items make the if statement (and the whole code) a little more verbose and redundant.

It's basically to improve readability, since in the archive context I use it the meaning of its items are pretty obvious and, in the algorithms, the name is used to define the variables that store this values is the same Emun name, so it gets a little redundant — artu-hnrq, Dec 21 '19 at 15:24
"... the name is used to define the variables that store this values is the same Emun name" Could you please post some code for context? I am not sure what you are trying to do. — Jaideep Shekhar, Dec 21 '19 at 15:31
Too late! Drat. You have got an answer. :-) In addition, [this post is an interesting read](https://stackoverflow.com/questions/2682745/how-do-i-create-a-constant-in-python). — Jaideep Shekhar, Dec 21 '19 at 15:48

Ethan Furman · Accepted Answer · 2019-12-21T15:50:10.067

First things first: inherit from Enum.

Like everything in Python, all you need to do is assign the names:

from enum import Enum

class MyEnum(Enum):
    ONE = 1
    TWO = 2

ONE = MyEnum.ONE
TWO = MyEnum.TWO

That can get annoying fast, so a helper function would be nice:

def export_enum(enum_cls, env):
    for member in enum_cls:
        env[member.name] = member

and in use:

>>> export_enum(MyEnum, globals())
>>> TWO
<MyEnum.TWO: 2>

If you use aenum¹ the export() function is already available, and can be used as a decorator:

from aenum import Enum, export

@export(globals())
class MyEnum(Enum):
    ONE = 1
    TWO = 2

The `aenum` decorator option is a pretty nice solution and I've already put it in use, +1. Thanks! — artu-hnrq, Dec 21 '19 at 16:00

1 Answers1