[Python-ideas] Allow isinstance second argument to be a set of types

[Devin Jeanpierre]

On Mon, Jul 4, 2011 at 5:08 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> Arbitrary iterables, arbitrarily nested...
>> beware of objects which are also their first element, like str('a')...
>
> Ouch. I guess that shoots the proposal dead in the water, then.

Wasn't the suggestion only for flat iterables, like {int, float,
complex}, rather than nested iterables?

I'm ambivalent, as long as the implementation is careful to make sure
one can still use isinstance on classes like these:

    class WeirdMetaclass(type):
        def __iter__(self):
            yield 1

    class MyObject(metaclass=WeirdMetaclass):
        pass

It still feels a little dirty though, to have to pick between options
that are not mutually exclusive.

Devin