enum.Enum, base class for creating enumerated constants

from enum import Enum

class Color(Enum):
    RED = 10
    GREEN = 20
    BLUE = 30
list(Color) # [, , ]
    
Animal = Enum('Animal', 'ANT BEE CAT DOG')
list(Animal) # [, , , ]
            

Color.RED == 10 # False

# Color.RED RED 10
# Color.GREEN GREEN 20
# Color.BLUE BLUE 30
for color in Color:
    print(color, color.name, color.value)

Color(10) # <Color.RED: 10>
Color['RED'] # <Color.RED: 10>
Color.RED # <Color.RED: 10>

Color(10) == Color.RED # True

Color(10).name # 'RED'
Color.RED.value # 10
            

Enum class decorator that ensures only one name is bound to any one value

# enum.unique()
from enum import Enum, unique

# enum allows different names have same value
class Mistake(Enum):
    ONE = 1
    TWO = 2
    THREE = 3
    FOUR = 3

# decorator unique guarrantee all values are unique
# if more than one names have same value, throw ValueError
@unique
class Mistake2(Enum):
    ONE = 1
    TWO = 2
    THREE = 3
    FOUR = 3
            

# enum.auto
from enum import Enum, auto
class Color(Enum):
    RED = auto()
    BLUE = auto()
    GREEN = auto()

print(list(Color)) # [, , ]
            

A subclass of enum. Assign each item an integer value

# enum.IntEnum
from enum import IntEnum

class Shape(IntEnum):
    CIRCLE = 1
    SQUARE = 2
    
print(Shape.CIRCLE == 1) # True
            

Integer-based enum

Members can be combined using the bitwise operators (&, |, ^, ~)

# enum.IntFlag
from enum import IntFlag

class Perm(IntFlag):
    R = 4
    W = 2
    X = 1
    
a = Perm.R | Perm.W # Perm.R|W
print(a.value) # 6
b = Perm.R + Perm.W 
print(b) # 6
            

Members can be combined using the bitwise operators (&, |, ^, ~)

cannot be combined with, nor compared against, any other Flag enumeration, nor int

# enum.Flag
from enum import Flag, auto

class Color(Flag):
    RED = auto()
    BLUE = auto()
    GREEN = auto()

print(list(Color)) # [<Color.RED: 1>, <Color.BLUE: 2>, <Color.GREEN: 4>]

Color.RED & Color.GREEN # <Color.0: 0>
Color.RED | Color.GREEN # <Color.GREEN|RED: 5>
Color.RED ^ Color.GREEN # <Color.GREEN|RED: 5>
~ Color.RED # <Color.GREEN|BLUE: 6>
            

list(Color) # [<Color.RED: 10>, <Color.GREEN: 20>, <Color.BLUE: 30>]
            

Python 3 Standard Library

PyMOTW-3