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Confusing __class__ for instance of non-generic class that subclasses generic class #129

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Confusing __class__ for instance of non-generic class that subclasses generic class#129
Milestone
3.5.2

Description

@JukkaL
JukkaL
opened on May 21, 2015

The following program prints __main__.A[int] even though A is not generic. I'd expect it to print something like <class '__main__.A'>.

from typing import Iterator

class A(Iterator[int]):
    def __next__(self): pass

print(A().__class__)

Also, this does not generate an exception, even though A is not generic:

def f(x: A[int]) -> None: pass

Activity

  1. JukkaL
    changed the title [-]Confusing __class__ for instance of non-generic class that subclasses generic clsas[/-] [+]Confusing __class__ for instance of non-generic class that subclasses generic class[/+] on May 21, 2015
  2. gvanrossum
    added
    bug
    on May 21, 2015
  3. gvanrossum
    self-assigned this
    on May 21, 2015

  4. gvanrossum commented on May 21, 2015

    @gvanrossum
    gvanrossum
    on May 21, 2015
    Member

    I'm on the fence about calling this a bug. What I implemented in rev 25af77d is that no matter how you instantiate A, you always get the original class A as the instance's __class__. And that is what's happening here. It just so happens that the actual class A remembers its parameters. Regarding using A[int] later, that probably shouldn't be allowed -- I need to rework the logic here. This is also related to issue #115. I will have to come back to this later.

  5. benjaminp
    unassigned
    gvanrossum
    on Jan 23, 2016
  6. gvanrossum
    added this to the 3.5.2 milestone on Apr 4, 2016

  7. gvanrossum commented on Apr 4, 2016

    @gvanrossum
    gvanrossum
    on Apr 4, 2016
    Member

    OK, fixed by #195.

  8. gvanrossum
    closed this as completedon Apr 4, 2016
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