Mypy: Classes with __call__ defined should be a subtype of Callable

[zhangwen0411]

def apply(f: Callable[[int], int], x: int) -> int:
  return f(x)

class Add5(object):
  def __call__(self, x: int) -> int:
    return x + 5

apply(Add5(), 5)

This code snippet doesn't type check because Mypy doesn't treat Add5() as a Callable[[int], int]

[JukkaL]

Moved to 0.5 since this comes up pretty frequently.

[margaret]

I'm going to start looking into this one.

[margaret]

WIP at https://github.com/margaret/mypy/tree/user_defined_callable (thanks @rwbarton for helping)
Currently debugging broken tests, specifically

class A(type):
    def __init__(self) -> None: pass
def f(x: type): pass
f(A())

Does not work and returns
error: Argument 1 to "f" has incompatible type Callable[[Any, Any], Any]; expected "type"

[gvanrossum]

Have you tried putting a pdb.set_trace() call in errors.Errors.report()
and tracing back to the cause of this message?

I believe type is special in some ways, maybe that's biting you?

On Fri, Jun 3, 2016 at 7:33 PM, Margaret Sy [email protected]
wrote:

WIP at https://github.com/margaret/mypy/tree/user_defined_callable
Currently debugging broken tests, specifically

class A(type):
def init(self) -> None: pass
def f(x: type): pass
f(A())

Does not work and returns
error: Argument 1 to "f" has incompatible type Callable[[Any, Any], Any];
expected "type"

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[gvanrossum]

Moving to an earlier milestone since the partial issue is kind of important.

[JukkaL]

A related issue is the join of Callable and an instance type that defines __call__ (see #2779).

[gvanrossum]

@ilevkivskyi Are you still working on this? If not it's better to un-assign.

[ilevkivskyi]

Protocols #3132 will fix this, no additional work here will be needed when they are merged.

[ilevkivskyi]

This is now fixed by #3132