patternpythonMinor
An attempt at a simple type safe python enum
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simpleenumattempttypepythonsafe
Problem
There have been many posts here about enums in python, but none seem to be both type safe and simple. Here is my attempt at it. Please let me know if you see anything obviously wrong with it.
Then to test it:
def typeSafeEnum(enumName, *sequential):
topLevel = type(enumName, (object,), dict(zip(sequential, [None] * len(sequential))))
vals = map(lambda x: type(x,(topLevel,),{}), sequential)
for k, v in zip(sequential, vals):
setattr(topLevel, k, v())
return topLevelThen to test it:
Colors = typeSafeEnum('Colors', 'RED', 'GREEN', 'BLUE')
if __name__ == '__main__':
x = Colors.RED
assert isinstance(x, Colors)Solution
def typeSafeEnum(enumName, *sequential):Python convention is
lowercase_with_underscores for functions and parameters. Although since this is a type factory its not totally clear what convention should appply. I also wonder if passing the enum values as a list might be better.topLevel = type(enumName, (object,), dict(zip(sequential, [None] * len(sequential))))There is no point in the dict you are passing since you just setattr all the enums in place already. Here you set all the enum values up with None initially and then fill them in. Why? I can also see why you call this topLevel but its not an immeadiately obvious name
vals = map(lambda x: type(x,(topLevel,),{}), sequential)List comprehensions are generally preffered to calling map with a lambda. But also, why? Just do this in the for loop. You don't gain anything by having it done in a map and then zipping over it.
for k, v in zip(sequential, vals):I suggest longer less abbreviated names
setattr(topLevel, k, v())
return topLevelCode Snippets
def typeSafeEnum(enumName, *sequential):topLevel = type(enumName, (object,), dict(zip(sequential, [None] * len(sequential))))vals = map(lambda x: type(x,(topLevel,),{}), sequential)for k, v in zip(sequential, vals):setattr(topLevel, k, v())
return topLevelContext
StackExchange Code Review Q#24536, answer score: 3
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