This is a fork of recipe #577024 which describes an enum type for Python using __slots__ and read-only variables. Apart from the enum with default positional argument values, this one adds another enum type using keyword arguments.
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | # Enum type with default positional values
# Enum('STATE', 'A','B','C') => returns object
# e so that e.A=>0, e.B=>1, e.C=>2 etc.
def Enum(name, *args):
args_m = [arg for arg in args if type(arg)==str]
return type(name, (object,), dict(((v,k) for k, v in enumerate(args_m)), __slots__=args_m))()
# Enum type with keyword values
# Enum('STATE',A=1, B=3,C=2) => returns object
# e so that e.A=1, e.B=>3, e.C=>2 etc.
Enum_kw = lambda name, **kwargs: type(name, (object,), [item for item in (kwargs.update({'__slots__': [k for k in kwargs]}), kwargs)][1])()
e=Enum('STATE','A','B','C','D')
print e.A, e.B, e.C
#e.A=1 # Can't do this
#e.X=100 # Can't do this
e=Enum_kw('STATE',A=1,B=2,C=3)
print e.A, e.B, e.C
# Can't change existing attribute
# e.A=10
# Can't assign new attributes
# e.X=100
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This is a concise rewrite of the Enum type in recipe #577024 and also adds a keyword enum type. The main difference is that this uses positional and keyword arguments and supplies a secondary enum type. __slots__ is used here also and the enum values remain read-only.
Tags: enum
