Lets say in python
StateA = 1
StateB = 2
StateC = StateA | StateB
...
instance.state = StateA
in C# there is a HasFlag function in Enum, which tells me an object's flag is part of StateC
Is there a equivalent version in python?
Right now I can only think (as bitwise noob) of this and not even sure if it supposed to work:
if instance.state | StateC == StateC:
# yes in StateC
Python 3.4 has an Enum data type, which has been backported.
from enum import Enum
class States(Enum):
StateA = 1
StateB = 2
StateC = StateA | StateB
def has_flag(self, flag):
return self.value & flag.value
if States.StateC.has_flag(States.StateA):
print("yup, it's there!")
Python 3.6 has the (Int)Flag data type, which is also present in the aenum1 library:
from enum import Flag # or from aenum import Flag
class States(Flag):
StateA = 1
StateB = 2
StateC = StateA | StateB
if States.StateA in States.StateC:
print("yup, it's there!")
1 Disclosure: I am the author of the Python stdlib Enum, the enum34 backport, and the Advanced Enumeration (aenum) library.
Testing for a flag:
value & flag == flag
Adding a flag:
value |= flag
Clearing a flag:
value &= ~flag
HasFlag is basically bitwise operation.
>>> a = 0b01
>>> b = 0b10
>>> "{0:b}".format(a | b,)
'11'
>>> def has_flag(v, flag): return v & flag == flag
...
>>> has_flag(0b111, a)
True
>>> has_flag(0b111, a|b)
True
>>> has_flag(0b1, a|b)
False
