[Python-Dev] constant/enum type in stdlib (original) (raw)

Ben.Cottrell at nominum.com Ben.Cottrell at nominum.com
Tue Nov 23 16:37:43 CET 2010

On Tue, 23 Nov 2010 15:15:29 +0000, Michael Foord wrote:

There are still two reasonable APIs (unless you have changed your mind and think that sticking with plain integers is best), of which I prefer the latter:

SOMECONST = Constant('SOMECONST', 1) OTHERCONST = Constant('OTHERCONST', 2) or: Constants = makeconstants('Constants', 'SOMECONST OTHERCONST', start=1) SOMECONST = Constants.SOMECONST OTHERCONST = Constants.OTHERCONST

I prefer the latter too, because that makes it possible to have 'Constants' be a rendezvous point for making sure that you're passing something valid. Perhaps using 'in':

def func(foo): if foo not in Constants: raise ValueError('foo must be SOME_CONST or OTHER_CONST') ...

I know this is probably not going to happen, but I would so much like it if functions would start rejecting "the wrong kind of 2". Constants that are valid, integer-wise, but which aren't part of the set of constants allowed for that argument. I'd prefer not to think of the number of times I've made the following mistake:

s = socket.socket(socket.SOCK_DGRAM, socket.AF_INET)

~Ben

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