I'm mainly a C# developer, but I'm currently working on a project in Python.
How can I represent the equivalent of an Enum in Python?
Enums have been added to Python 3.4 as described in PEP 435. It has also been backported to 3.3, 3.2, 3.1, 2.7, 2.6, 2.5, and 2.4 on pypi.
For more advanced Enum techniques try the aenum library (2.7, 3.3+, same author as
$ pip install enum34
$ pip install aenum
enum (no numbers) will install a completely different and incompatible version.
from enum import Enum # for enum34, or the stdlib version # from aenum import Enum # for the aenum version Animal = Enum('Animal', 'ant bee cat dog')
class Animal(Enum): ant = 1 bee = 2 cat = 3 dog = 4
In earlier versions, one way of accomplishing enums is:
def enum(**enums): return type('Enum', (), enums)
which is used like so:
>>> Numbers = enum(ONE=1, TWO=2, THREE='three') >>> Numbers.ONE 1 >>> Numbers.TWO 2 >>> Numbers.THREE 'three'
You can also easily support automatic enumeration with something like this:
def enum(*sequential, **named): enums = dict(zip(sequential, range(len(sequential))), **named) return type('Enum', (), enums)
and used like so:
>>> Numbers = enum('ZERO', 'ONE', 'TWO') >>> Numbers.ZERO 0 >>> Numbers.ONE 1
Support for converting the values back to names can be added this way:
def enum(*sequential, **named): enums = dict(zip(sequential, range(len(sequential))), **named) reverse = dict((value, key) for key, value in enums.iteritems()) enums['reverse_mapping'] = reverse return type('Enum', (), enums)
This overwrites anything with that name, but it is useful for rendering your enums in output. It will throw KeyError if the reverse mapping doesn't exist. With the first example:
>>> Numbers.reverse_mapping['three'] 'THREE'