How To Define Custom Properties In Enumeration In Python (javascript-like)

In JavaScript we can do this: var Color = { YELLOW: { value: 1, displayString: 'Yellow' }, GREEN: { value: 2, displayString: 'Green' }, } So I can call: Color.YELLOW.displ

Solution 1:

There are two concepts involved here: enumerations and attribute-style access to object members that can be initialised inline. For the latter, you'll need some kind of custom class, but since you want something very straightforward, a namedtuple is sufficient for that. So, combining namedtuple and enum, this could be a solution:

from enum import Enum
from collections import namedtuple

Color = namedtuple('Color', ['value', 'displayString'])

classColors(Enum):

    @propertydefdisplayString(self):
        return self.value.displayString

    yellow = Color(1, 'Yellow')
    green = Color(2, 'Green')

print(Colors.yellow.displayString)

Solution 2:

Here is another approach, that is the code from: https://github.com/hzdg/django-enumfields

import enum
import inspect

classColorEnumMeta(enum.EnumMeta):
    def__new__(mcs, name, bases, attrs):
        DisplayStrings = attrs.get('DisplayStrings')

        if DisplayStrings isnotNoneand inspect.isclass(DisplayStrings):
            del attrs['DisplayStrings']
            ifhasattr(attrs, '_member_names'):
                attrs._member_names.remove('DisplayStrings')

        obj = super().__new__(mcs, name, bases, attrs)
        for m in obj:
            m.display_string = getattr(DisplayStrings, m.name, None)

        return obj

classColor(enum.Enum, metaclass=ColorEnumMeta):
    yellow = 1
    green = 2classDisplayStrings:
        yellow = 'Yellow'
        green = 'Green'print(Color.yellow.display_string)  # 'Yellow'

or something that is based on this code, but a bit shorter:

import enum

classColorEnumMeta(enum.EnumMeta):
    def__new__(mcs, name, bases, attrs):
        obj = super().__new__(mcs, name, bases, attrs)
        obj._value2member_map_ = {}
        for m in obj:
            value, display_string = m.value
            m._value_ = value
            m.display_string = display_string
            obj._value2member_map_[value] = m

        return obj

classColor(enum.Enum, metaclass=ColorEnumMeta):
    yellow = 1, 'Yellow'
    green = 2, 'Green'print(Color.yellow.display_string)  # 'Yellow'

Solution 3:

You can use a dictionary in python:

Color = { 
    'YELLOW': { 'value': 1, 'displayString': "Yellow" },
    'GREEN': { 'value': 2, 'displayString': "Green" }
}
Color['YELLOW']['displayString']

Solution 4:

You should normally never include literals like this in your code. The content should come from a file or database. But you can see how to build it up

>>> from collections import namedtuple
>>> Color = namedtuple("color", "YELLOW,GREEN")(
        namedtuple("yellow", "value,display_string")(1, "yellow"),
        namedtuple("green", "value,display_string")(2, "green"))
>>> Color.YELLOW.display_string
'yellow'

This also works for older Pythons that don't support enum