Decorated bound instance method cannot be inferred correctly. #3954
Description
Note: if you are reporting a wrong signature of a function or a class in the standard library, then the typeshed tracker is better suited for this report: https://github.com/python/typeshed/issues.
Describe the bug
A clear and concise description of what the bug is.
from typing import Callable, TypeVar
from typing_extensions import Concatenate, ParamSpec
_S = TypeVar('_S')
_P = ParamSpec('_P')
_R = TypeVar('_R')
def proxy_method(method: Callable[[_S], Callable[_P, _R]]) -> Callable[Concatenate[_S, _P], _R]:
def new_method(_self: _S, *args: _P.args, **kwargs: _P.kwargs):
other_method = method(_self)
return other_method(*args, **kwargs)
return new_method
class Foo:
def do_something(self, x: int):
return 42 + x
class Bar:
def __init__(self):
self.foo = Foo()
@proxy_method
def do_something(self):
return self.foo.do_something
def do_other(self, x: int):
return x + 1
def debug():
Bar.do_something
Bar.do_other
bar = Bar()
print(bar.do_other(1))
print(bar.do_something(1))proxy_method decorates an instance method (Bar.do_something). The instance method to be decorated should return a callable (self.foo.do_something). proxy_method should return a new instance method (function) simply acting as a proxy method to the the callable. Hence, calling bar.do_something(1) is equivalent to calling bar.foo.do_something(1).
But pyright cannot infer the bound instance method correctly:
(bar.do_something should be inferred as bound, and should not raise a type error)
And I also notice pyright treats the "naive" instance method (function) and the decorated one differently:
(Bar.do_something is decorated)
(Bar.do_other is not decorated)
To Reproduce
Steps to reproduce the behavior.
aforementioned.
Expected behavior
A clear and concise description of what you expected to happen.
bar.do_something should be inferred as bound, and should not raise a type error, just like bar.do_other:
Screenshots or Code
If applicable, add screenshots or the text of the code (surrounded by triple back ticks) to help explain your problem.
def foo(self) -> str:
return 3inlined.
If your code relies on symbols that are imported from a third-party library, include the associated import statements and specify which versions of those libraries you have installed.
VS Code extension or command-line
Are you running pyright as a VS Code extension or a command-line tool? Which version? You can find the version of the VS Code extension by clicking on the Pyright icon in the extensions panel.
I'm running pyright v1.1.271 as a VS Code extension.
Additional context
Add any other context about the problem here.