On Tuesday, May 2, 2017 at 11:45:39 AM UTC-4, oliver wrote:
> The documentation for typing.TypeVar gives these two examples:
>
> T = TypeVar('T') # Can be anything
> A = TypeVar('A', str, bytes) # Must be str or bytes
>
> I was suprised to find out that the following does not work, exception says
> that TypeVar is not definable with only one constraint:
>
> A = TypeVar('A', type) # Must be a type, like class Foo, etc (rather
> than an instance of a type)
>
> The TypeVar source code explicitely forbids only one type constraint, what
> is the rationale behind this?
>
> For those who wonder, my function parameter expects a type rather than an
> instance of a type, and returns a type.
Couldn't you simply annotate it as ": type", without using a TypeVar?
--Ned.
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