[Python-Dev] Enum: subclassing? (original) (raw)

Georg Brandl g.brandl at gmx.net
Wed May 1 20:47:19 CEST 2013

Am 01.05.2013 20:04, schrieb Eli Bendersky:

Actually, in flufl.enum, IntEnum had to define a magic valuefactory attribute, but in the current ref435 implementation this isn't needed, so IntEnum is just:

class IntEnum(int, Enum): ''' Class where every instance is a subclass of int. ''' So why don't we just drop IntEnum from the API and tell users they should do the above explicitly, i.e.: class SocketFamily(int, Enum): AFUNIX = 1 AFINET = 2 As opposed to having an IntEnum explicitly, this just saves 2 characters (comma+space), but is more explicit (zen!) and helps us avoid the special-casing the subclass restriction implementation.

Wait a moment... it might not be immediately useful for IntEnums (however, that's because base Enum currently defines int which I find questionable), but with current ref435 you can create your own enum base classes with your own methods, and derive concrete enums from that. It also lets you have a base class for enums and use it in isinstance().

If you forbid subclassing completely that will be impossible.

Georg

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