Python Enum Module
The enum module defines four enumeration classes that can be used to define unique sets of names and values: Enum, IntEnum, Flag, and IntFlag. It also defines one decorator, unique, and one helper, auto.
Importing the Module
import enumCreating an Enum
Enumerations are created using the class syntax, which makes them easy to read and write.
from enum import Enum
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3auto()
If the exact value is unimportant you can use auto().
from enum import Enum, auto
class Color(Enum):
RED = auto()
GREEN = auto()
BLUE = auto()Iteration
You can iterate over the members of an enumeration.
class Shape(Enum):
SQUARE = 2
DIAMOND = 4
CIRCLE = 3
for shape in Shape:
print(shape.name, shape.value)Comparisons
Enum members are compared by identity.
if Shape.SQUARE is Shape.SQUARE:
print("Identity comparison works")IntEnum
IntEnum is the same as Enum, but its members are also integers and can be compared to integers.
from enum import IntEnum
class Shape(IntEnum):
CIRCLE = 1
SQUARE = 2
print(Shape.CIRCLE == 1) # TrueFlag and IntFlag
Flag and IntFlag are used to define enumerations that can be combined using bitwise operators.
from enum import Flag, auto
class Color(Flag):
RED = auto()
GREEN = auto()
BLUE = auto()
WHITE = RED | GREEN | BLUE
print(Color.WHITE) # Color.WHITE
print(Color.RED in Color.WHITE) # TrueThe unique Decorator
By default, enumerations allow aliases (multiple names for the same value). To disallow this, use the @unique decorator.
from enum import Enum, unique
@unique
class Mistake(Enum):
ONE = 1
TWO = 2
THREE = 3
# FOUR = 3 # This would raise a ValueErrorProgrammatic Access
You can access members by name or value.
print(Color['RED']) # Color.RED
print(Color(1)) # Color.RED (assuming RED=1)