Indeed, the "type(Color.red) is Color" claim was meant for the
situation where red is defined directly in Color, and I used type()
instead of isinstance() because Barry was proposing to overload
isinstance() to make this true without equating the classes. But for
the subclass case, I want MoreColor.red is Color.red and
isinstance(MoreColor.red, Color), but not isinstance(Color.red,
MoreColor). If you can't live with that, don't subclass enums.
On Mon, Apr 29, 2013 at 6:32 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
> [creating new thread]
>> On 04/29/2013 01:30 AM, Steven D'Aprano wrote:
>>>> On Sun, Apr 28, 2013 at 11:50:16PM -0700, Ethan Furman wrote:
>>>>> In other words, currently:
>>>>>> class Color(Enum):
>>> red = 1
>>> green = 2
>>> blue = 3
>>>>>> class MoreColor(Color):
>>> cyan = 4
>>> magenta = 5
>>> yellow = 6
>>> black = 7
>>>>>> MoreColor.red is Color.red # True
>>>>>> Correct.
>>>>>>> But as soon as:
>>>>>> type(Color.red) is Color # True
>>> type(MoreColor.red) is MoreColor # True
>>>>>> I don't believe this is correct. As I understand it, the proposal is the
>> weaker guarantee:
>>>> isinstance(Color.red, Color) # True, possibly using __instancecheck__
>>>> Words from Guido:
>> On 04/23/2013 08:11 AM, Guido van Rossum wrote:
>>>> I gotta say, I'm with Antoine here. It's pretty natural (also coming
>> from other languages) to assume that the class used to define the
>> enums is also the type of the enum values. Certainly this is how it
>> works in Java and C++, and I would say it's the same in Pascal and
>> probably most other languages.
>>>> On 04/25/2013 02:54 PM, Guido van Rossum wrote:
>>>> I don't know what's going on, but it feels like we had this same
>> discussion a week ago, and I still disagree. Disregarding, the C[i]
>> notation, I feel quite strongly that in the following example:
>>>> class Color(Enum):
>> red = 1
>> white = 2
>> blue = 3
>> orange = 4
>>>> the values Color.red etc. should be instances of Color. This is how
>> things work in all other languages that I am aware of that let you
>> define enums.
>>> On 04/25/2013 03:19 PM, Guido van Rossum wrote:
>>>> I suppose you were going to propose to use isinstance() overloading,
>> but I honestly think that Color.red.__class__ should be the same
>> object as Color.
>>> On 04/25/2013 03:37 PM, Guido van Rossum wrote:
>>>> TBH I had a hard time getting over the fact that even though the class
>> said "a = 1", C.a is not the integer 1. But I did get over it.
>> Hopefully you can get over *this* weirdness.
>>> [and from the summary thread]
>> On 04/28/2013 01:02 PM, Guido van Rossum wrote:
>>>> On Sun, Apr 28, 2013 at 12:32 PM, Ethan Furman wrote:
>>>>>>>>> - should enum items be of the type of the Enum class? (i.e.
>>> type(SPRING)
>>> is Seasons)
>>>>>> IMO Yes.
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--
--Guido van Rossum (python.org/~guido)
