[Python-Dev] PEP 435 -- Adding an Enum type to the Python standard library (original) (raw)

Ethan Furman ethan at stoneleaf.us
Fri Apr 12 17:31:29 CEST 2013

On 04/12/2013 08:02 AM, Barry Warsaw wrote:

On Apr 12, 2013, at 03:31 PM, Dirkjan Ochtman wrote:

On Fri, Apr 12, 2013 at 2:55 PM, Eli Bendersky <eliben at gmail.com> wrote: Ordered comparisons between enumeration values are not supported. Enums are not integers (but see IntEnum below)::

>>> Colors.red < Colors.blue_ _Traceback (most recent call last):_ _..._ _NotImplementedError_ _>>> Colors.red <= Colors.blue_ _Traceback (most recent call last):_ _..._ _NotImplementedError_ _>>> Colors.blue > Colors.green Traceback (most recent call last): ... NotImplementedError >>> Colors.blue >= Colors.green Traceback (most recent call last): ... NotImplementedError I like much of this PEP, but the exception type for this case seems odd to me. Wouldn't a TypeError be more appropriate here? Somewhat like this:

'a' - 'b' Traceback (most recent call last): File "", line 1, in TypeError: unsupported operand type(s) for -: 'str' and 'str' Interesting. I'm having a hard time articulating why, but NotImplementedError just feels more right to me in this case.

NotImplemented makes it seem like we could implement it in a subclass -- is this true?

Also, for a more direct comparison:

--> 'a' < 1 Traceback (most recent call last): File "", line 1, in TypeError: unorderable types: str() < int()

I would think this is the more appropriate exception and text to use.

-- Ethan

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