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Methods

Background: Functions as descriptors

Note: See also this related section in the descriptor guide: Functions and methods.

Say we have a simple class C with a function definition f inside its body:

class C:
    def f(self, x: int) -> str:
        return "a"

Whenever we access the f attribute through the class object itself (C.f) or through an instance (C().f), this access happens via the descriptor protocol. Functions are (non-data) descriptors because they implement a __get__ method. This is crucial in making sure that method calls work as expected. In general, the signature of the __get__ method in the descriptor protocol is __get__(self, instance, owner). The self argument is the descriptor object itself (f). The passed value for the instance argument depends on whether the attribute is accessed from the class object (in which case it is None), or from an instance (in which case it is the instance of type C). The owner argument is the class itself (C of type Literal[C]). To summarize:

  • C.f is equivalent to getattr_static(C, "f").__get__(None, C)
  • C().f is equivalent to getattr_static(C, "f").__get__(C(), C)

Here, inspect.getattr_static is used to bypass the descriptor protocol and directly access the function attribute. The way the special __get__ method on functions works is as follows. In the former case, if the instance argument is None, __get__ simply returns the function itself. In the latter case, it returns a bound method object:

from inspect import getattr_static

reveal_type(getattr_static(C, "f"))  # revealed: def f(self, x: int) -> str

# revealed: <method-wrapper '__get__' of function 'f'>
reveal_type(getattr_static(C, "f").__get__)

reveal_type(getattr_static(C, "f").__get__(None, C))  # revealed: def f(self, x: int) -> str
reveal_type(getattr_static(C, "f").__get__(C(), C))  # revealed: bound method C.f(x: int) -> str

In conclusion, this is why we see the following two types when accessing the f attribute on the class object C and on an instance C():

reveal_type(C.f)  # revealed: def f(self, x: int) -> str
reveal_type(C().f)  # revealed: bound method C.f(x: int) -> str

A bound method is a callable object that contains a reference to the instance that it was called on (can be inspected via __self__), and the function object that it refers to (can be inspected via __func__):

bound_method = C().f

reveal_type(bound_method.__self__)  # revealed: C
reveal_type(bound_method.__func__)  # revealed: def f(self, x: int) -> str

When we call the bound method, the instance is implicitly passed as the first argument (self):

reveal_type(C().f(1))  # revealed: str
reveal_type(bound_method(1))  # revealed: str

When we call the function object itself, we need to pass the instance explicitly:

# error: [invalid-argument-type] "Argument to function `f` is incorrect: Expected `C`, found `Literal[1]`"
# error: [missing-argument]
C.f(1)

reveal_type(C.f(C(), 1))  # revealed: str

When we access methods from derived classes, they will be bound to instances of the derived class:

class D(C):
    pass

reveal_type(D().f)  # revealed: bound method D.f(x: int) -> str

If we access an attribute on a bound method object itself, it will defer to types.MethodType:

reveal_type(bound_method.__hash__)  # revealed: bound method MethodType.__hash__() -> int

If an attribute is not available on the bound method object, it will be looked up on the underlying function object. We model this explicitly, which means that we can access __kwdefaults__ on bound methods, even though it is not available on types.MethodType:

reveal_type(bound_method.__kwdefaults__)  # revealed: dict[str, Any] | None

Basic method calls on class objects and instances

class Base:
    def method_on_base(self, x: int | None) -> str:
        return "a"

class Derived(Base):
    def method_on_derived(self, x: bytes) -> tuple[int, str]:
        return (1, "a")

reveal_type(Base().method_on_base(1))  # revealed: str
reveal_type(Base.method_on_base(Base(), 1))  # revealed: str

Base().method_on_base("incorrect")  # error: [invalid-argument-type]
Base().method_on_base()  # error: [missing-argument]
Base().method_on_base(1, 2)  # error: [too-many-positional-arguments]

reveal_type(Derived().method_on_base(1))  # revealed: str
reveal_type(Derived().method_on_derived(b"abc"))  # revealed: tuple[int, str]
reveal_type(Derived.method_on_base(Derived(), 1))  # revealed: str
reveal_type(Derived.method_on_derived(Derived(), b"abc"))  # revealed: tuple[int, str]

Method calls on literals

Boolean literals

reveal_type(True.bit_length())  # revealed: int
reveal_type(True.as_integer_ratio())  # revealed: tuple[int, Literal[1]]

Integer literals

reveal_type((42).bit_length())  # revealed: int

String literals

reveal_type("abcde".find("abc"))  # revealed: int
reveal_type("foo".encode(encoding="utf-8"))  # revealed: bytes

"abcde".find(123)  # error: [invalid-argument-type]

Bytes literals

reveal_type(b"abcde".startswith(b"abc"))  # revealed: bool

Method calls on LiteralString

from typing_extensions import LiteralString

def f(s: LiteralString) -> None:
    reveal_type(s.find("a"))  # revealed: int

Method calls on tuple

def f(t: tuple[int, str]) -> None:
    reveal_type(t.index("a"))  # revealed: int

Method calls on unions

from typing import Any

class A:
    def f(self) -> int:
        return 1

class B:
    def f(self) -> str:
        return "a"

def f(a_or_b: A | B, any_or_a: Any | A):
    reveal_type(a_or_b.f)  # revealed: (bound method A.f() -> int) | (bound method B.f() -> str)
    reveal_type(a_or_b.f())  # revealed: int | str

    reveal_type(any_or_a.f)  # revealed: Any | (bound method A.f() -> int)
    reveal_type(any_or_a.f())  # revealed: Any | int

Method calls on KnownInstance types

[environment]
python-version = "3.12"
type IntOrStr = int | str

reveal_type(IntOrStr.__or__)  # revealed: bound method TypeAliasType.__or__(right: Any, /) -> _SpecialForm

Method calls on types not disjoint from None

Very few methods are defined on object, None, and other types not disjoint from None. However, descriptor-binding behavior works on these types in exactly the same way as descriptor binding on other types. This is despite the fact that None is used as a sentinel internally by the descriptor protocol to indicate that a method was accessed on the class itself rather than an instance of the class:

from typing import Protocol, Literal
from ty_extensions import AlwaysFalsy

class Foo: ...

class SupportsStr(Protocol):
    def __str__(self) -> str: ...

class Falsy(Protocol):
    def __bool__(self) -> Literal[False]: ...

def _(a: object, b: SupportsStr, c: Falsy, d: AlwaysFalsy, e: None, f: Foo | None):
    a.__str__()
    b.__str__()
    c.__str__()
    d.__str__()
    e.__str__()
    f.__str__()

Method calls on subclasses of Any

from typing_extensions import assert_type, Any

class SubclassOfAny(Any):
    def method(self) -> int:
        return 1

a = SubclassOfAny()
assert_type(a.method(), int)

assert_type(a.non_existing_method(), Any)

Error cases: Calling __get__ for methods

The __get__ method on types.FunctionType has the following overloaded signature in typeshed:

from types import FunctionType, MethodType
from typing import overload

@overload
def __get__(self, instance: None, owner: type, /) -> FunctionType: ...
@overload
def __get__(self, instance: object, owner: type | None = None, /) -> MethodType: ...

Here, we test that this signature is enforced correctly:

from inspect import getattr_static

class C:
    def f(self, x: int) -> str:
        return "a"

method_wrapper = getattr_static(C, "f").__get__

reveal_type(method_wrapper)  # revealed: <method-wrapper '__get__' of function 'f'>

# All of these are fine:
method_wrapper(C(), C)
method_wrapper(C())
method_wrapper(C(), None)
method_wrapper(None, C)

reveal_type(object.__str__.__get__(object(), None)())  # revealed: str

# TODO: passing `None` without an `owner` argument fails at runtime.
# Ideally we would emit a diagnostic here:
method_wrapper(None)

# Passing something that is not assignable to `type` as the `owner` argument is an
# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
method_wrapper(None, 1)

# TODO: passing `None` as the `owner` argument when `instance` is `None` fails at runtime.
# Ideally we would emit a diagnostic here.
method_wrapper(None, None)

# Calling `__get__` without any arguments is an
# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
method_wrapper()

# Calling `__get__` with too many positional arguments is an
# error: [no-matching-overload] "No overload of method wrapper `__get__` of function `f` matches arguments"
method_wrapper(C(), C, "one too many")

Fallback to metaclass

When a method is accessed on a class object, it is looked up on the metaclass if it is not found on the class itself. This also creates a bound method that is bound to the class object itself:

from __future__ import annotations

class Meta(type):
    def f(cls, arg: int) -> str:
        return "a"

class C(metaclass=Meta):
    pass

reveal_type(C.f)  # revealed: bound method <class 'C'>.f(arg: int) -> str
reveal_type(C.f(1))  # revealed: str

The method f cannot be accessed from an instance of the class:

# error: [unresolved-attribute] "Object of type `C` has no attribute `f`"
C().f

A metaclass function can be shadowed by a method on the class:

from typing import Any, Literal

class D(metaclass=Meta):
    def f(arg: int) -> Literal["a"]:
        return "a"

reveal_type(D.f(1))  # revealed: Literal["a"]

If the class method is possibly missing, we union the return types:

def flag() -> bool:
    return True

class E(metaclass=Meta):
    if flag():
        def f(arg: int) -> Any:
            return "a"

reveal_type(E.f(1))  # revealed: str | Any

@classmethod

Basic

When a @classmethod attribute is accessed, it returns a bound method object, even when accessed on the class object itself:

from __future__ import annotations

class C:
    @classmethod
    def f(cls: type[C], x: int) -> str:
        return "a"

reveal_type(C.f)  # revealed: bound method <class 'C'>.f(x: int) -> str
reveal_type(C().f)  # revealed: bound method type[C].f(x: int) -> str

The cls method argument is then implicitly passed as the first argument when calling the method:

reveal_type(C.f(1))  # revealed: str
reveal_type(C().f(1))  # revealed: str

When the class method is called incorrectly, we detect it:

C.f("incorrect")  # error: [invalid-argument-type]
C.f()  # error: [missing-argument]
C.f(1, 2)  # error: [too-many-positional-arguments]

If the cls parameter is wrongly annotated, we emit an error at the call site:

class D:
    @classmethod
    def f(cls: D):
        # This function is wrongly annotated, it should be `type[D]` instead of `D`
        pass

# error: [invalid-argument-type] "Argument to bound method `f` is incorrect: Expected `D`, found `<class 'D'>`"
D.f()

When a class method is accessed on a derived class, it is bound to that derived class:

class Derived(C):
    pass

reveal_type(Derived.f)  # revealed: bound method <class 'Derived'>.f(x: int) -> str
reveal_type(Derived().f)  # revealed: bound method type[Derived].f(x: int) -> str

reveal_type(Derived.f(1))  # revealed: str
reveal_type(Derived().f(1))  # revealed: str

Accessing the classmethod as a static member

Accessing a @classmethod-decorated function at runtime returns a classmethod object. We currently don't model this explicitly:

from inspect import getattr_static

class C:
    @classmethod
    def f(cls): ...

reveal_type(getattr_static(C, "f"))  # revealed: def f(cls) -> Unknown
# revealed: <method-wrapper '__get__' of function 'f'>
reveal_type(getattr_static(C, "f").__get__)

But we correctly model how the classmethod descriptor works:

reveal_type(getattr_static(C, "f").__get__(None, C))  # revealed: bound method <class 'C'>.f() -> Unknown
reveal_type(getattr_static(C, "f").__get__(C(), C))  # revealed: bound method <class 'C'>.f() -> Unknown
reveal_type(getattr_static(C, "f").__get__(C()))  # revealed: bound method type[C].f() -> Unknown

The owner argument takes precedence over the instance argument:

reveal_type(getattr_static(C, "f").__get__("dummy", C))  # revealed: bound method <class 'C'>.f() -> Unknown

Implicit cls parameters should stay in class-object space when a classmethod is accessed through type[T]:

from typing import Any, Type, TypeVar

Model = TypeVar("Model", bound="BaseModel")

class BaseModel:
    @classmethod
    def normalize(cls, obj: Any) -> Any:
        return obj

    @classmethod
    def parse_obj(cls: Type[Model], obj: Any) -> Model:
        reveal_type(cls.normalize)  # revealed: bound method type[Model@parse_obj].normalize(obj: Any) -> Any

        cls.normalize(obj)
        cls.normalize.__func__(cls, obj)

        # error: [invalid-argument-type]
        cls.normalize.__func__(cls(), obj)
        return cls()

Classmethods mixed with other decorators

[environment]
python-version = "3.12"

When a @classmethod is additionally decorated with another decorator, it is still treated as a class method:

def does_nothing[T](f: T) -> T:
    return f

class C:
    @classmethod
    @does_nothing
    def f1(cls, x: int) -> str:
        return "a"

    @does_nothing
    @classmethod
    def f2(cls, x: int) -> str:
        return "a"

reveal_type(C.f1(1))  # revealed: str
reveal_type(C().f1(1))  # revealed: str
reveal_type(C.f2(1))  # revealed: str
reveal_type(C().f2(1))  # revealed: str

Classmethods with Self and callable-returning decorators

When a classmethod is decorated with a decorator that returns a callable type (like @contextmanager), Self in the return type should correctly resolve to the subclass when accessed on a derived class.

from contextlib import contextmanager
from typing import Iterator
from typing_extensions import Self

class Base:
    @classmethod
    @contextmanager
    def create(cls) -> Iterator[Self]:
        yield cls()

class Child(Base): ...

reveal_type(Base.create())  # revealed: _GeneratorContextManager[Base, None, None]
with Base.create() as base:
    reveal_type(base)  # revealed: Base

reveal_type(Base().create())  # revealed: _GeneratorContextManager[Base, None, None]
with Base().create() as base:
    reveal_type(base)  # revealed: Base

reveal_type(Child.create())  # revealed: _GeneratorContextManager[Child, None, None]
with Child.create() as child:
    reveal_type(child)  # revealed: Child

reveal_type(Child().create())  # revealed: _GeneratorContextManager[Child, None, None]
with Child().create() as child:
    reveal_type(child)  # revealed: Child

__init_subclass__

Basics

The __init_subclass__ method is implicitly a classmethod:

class Base:
    def __init_subclass__(cls, **kwargs):
        super().__init_subclass__(**kwargs)
        cls.custom_attribute: int = 0

class Derived(Base):
    pass

reveal_type(Derived.custom_attribute)  # revealed: int

Subclasses must be constructed with arguments matching the required arguments of the base __init_subclass__ method.

class Empty: ...

class RequiresArg:
    def __init_subclass__(cls, arg: int): ...

class NoArg:
    def __init_subclass__(cls): ...

# Single-base definitions
class MissingArg(RequiresArg): ...  # error: [missing-argument]
class InvalidType(RequiresArg, arg="foo"): ...  # error: [invalid-argument-type]
class Valid(RequiresArg, arg=1): ...

# error: [missing-argument]
# error: [unknown-argument]
class IncorrectArg(RequiresArg, not_arg="foo"):
    a = 1
    b = 2
    c = 3
    d = 4
    e = 5
    f = 6
    g = 7
    h = 8
    i = 9
    j = 10

class NotCallableInitSubclass:
    __init_subclass__ = None

# TODO: this should be an error because `__init_subclass__` on the superclass is not callable
class Bad(NotCallableInitSubclass):
    a = 1
    b = 2
    c = 3

The metaclass keyword is ignored, as it has special meaning and is not passed to __init_subclass__ at runtime.

class Base:
    def __init_subclass__(cls, arg: int): ...

class Valid(Base, arg=5, metaclass=object): ...

# error: [invalid-argument-type]
class Invalid(Base, metaclass=type, arg="foo"): ...

Overload matching is performed correctly:

from typing import Literal, overload

class Base:
    @overload
    def __init_subclass__(cls, mode: Literal["a"], arg: int) -> None: ...
    @overload
    def __init_subclass__(cls, mode: Literal["b"], arg: str) -> None: ...
    def __init_subclass__(cls, mode: str, arg: int | str) -> None: ...

class Valid(Base, mode="a", arg=5): ...
class Valid(Base, mode="b", arg="foo"): ...

# error: [no-matching-overload]
class InvalidType(Base, mode="b", arg=5):
    a = 1
    b = 2
    c = 3
    d = 4
    e = 5

More complex cases

For multiple inheritance, the first resolved __init_subclass__ method is used.

[environment]
python-version = "3.12"
class Empty: ...

class RequiresArg:
    def __init_subclass__(cls, arg: int): ...

class NoArg:
    def __init_subclass__(cls): ...

class Valid(NoArg, RequiresArg): ...
class MissingArg(RequiresArg, NoArg): ...  # error: [missing-argument]
class InvalidType(RequiresArg, NoArg, arg="foo"): ...  # error: [invalid-argument-type]
class Valid(RequiresArg, NoArg, arg=1): ...

# Ensure base class without __init_subclass__ is ignored
class Valid(Empty, NoArg): ...
class Valid(Empty, RequiresArg, NoArg, arg=1): ...
class MissingArg(Empty, RequiresArg): ...  # error: [missing-argument]
class MissingArg(Empty, RequiresArg, NoArg): ...  # error: [missing-argument]
class InvalidType(Empty, RequiresArg, NoArg, arg="foo"): ...  # error: [invalid-argument-type]

# Multiple inheritance with args
class Base(Empty, RequiresArg, NoArg, arg=1): ...
class Valid(Base, arg=1): ...
class MissingArg(Base): ...  # error: [missing-argument]
class InvalidType(Base, arg="foo"): ...  # error: [invalid-argument-type]

Keyword splats are allowed if their type can be determined:

from typing import TypedDict

class RequiresKwarg:
    def __init_subclass__(cls, arg: int): ...

class WrongArg(TypedDict):
    kwarg: int

class InvalidType(TypedDict):
    arg: str

wrong_arg: WrongArg = {"kwarg": 5}

# error: [missing-argument]
# error: [unknown-argument]
class MissingArg(RequiresKwarg, **wrong_arg): ...

invalid_type: InvalidType = {"arg": "foo"}

# error: [invalid-argument-type]
class InvalidType(RequiresKwarg, **invalid_type): ...

So are generics:

from typing import Generic, TypeVar, Literal, overload

class Base[T]:
    def __init_subclass__(cls, arg: T): ...

class Valid(Base[int], arg=1): ...
class InvalidType(Base[int], arg="x"): ...  # error: [invalid-argument-type]

# Old generic syntax
T = TypeVar("T")

class Base(Generic[T]):
    def __init_subclass__(cls, arg: T) -> None: ...

class Valid(Base[int], arg=1): ...
class InvalidType(Base[int], arg="x"): ...  # error: [invalid-argument-type]

@staticmethod

Basic

When a @staticmethod attribute is accessed, it returns the underlying function object. This is true whether it's accessed on the class or on an instance of the class.

from __future__ import annotations

class C:
    @staticmethod
    def f(x: int) -> str:
        return "a"

reveal_type(C.f)  # revealed: def f(x: int) -> str
reveal_type(C().f)  # revealed: def f(x: int) -> str

The method can then be called like a regular function from either the class or an instance, with no implicit first argument passed.

reveal_type(C.f(1))  # revealed: str
reveal_type(C().f(1))  # revealed: str

When the static method is called incorrectly, we detect it:

C.f("incorrect")  # error: [invalid-argument-type]
C.f()  # error: [missing-argument]
C.f(1, 2)  # error: [too-many-positional-arguments]

When a static method is accessed on a derived class, it behaves identically:

class Derived(C):
    pass

reveal_type(Derived.f)  # revealed: def f(x: int) -> str
reveal_type(Derived().f)  # revealed: def f(x: int) -> str

reveal_type(Derived.f(1))  # revealed: str
reveal_type(Derived().f(1))  # revealed: str

Staticmethod assigned in class body

Assigning a staticmethod(...) object directly in the class body should preserve the callable behavior of the wrapped function when accessed on both classes and instances.

def foo(*args, **kwargs) -> None:
    print("foo", args, kwargs)

class A:
    __call__ = staticmethod(foo)
    bar = staticmethod(foo)

a = A()
a()
a.bar()
a(5)
a.bar(5)
a(x=10)
a.bar(x=10)

A.bar()
A.bar(5)
A.bar(x=10)

Accessing the staticmethod as a static member

from inspect import getattr_static

class C:
    @staticmethod
    def f(): ...

Accessing the staticmethod as a static member. This will reveal the raw function, as staticmethod is transparent when accessed via getattr_static.

reveal_type(getattr_static(C, "f"))  # revealed: def f() -> Unknown

The __get__ of a staticmethod object simply returns the underlying function. It ignores both the instance and owner arguments.

reveal_type(getattr_static(C, "f").__get__(None, C))  # revealed: def f() -> Unknown
reveal_type(getattr_static(C, "f").__get__(C(), C))  # revealed: def f() -> Unknown
reveal_type(getattr_static(C, "f").__get__(C()))  # revealed: def f() -> Unknown
reveal_type(getattr_static(C, "f").__get__("dummy", C))  # revealed: def f() -> Unknown

Staticmethods mixed with other decorators

[environment]
python-version = "3.12"

When a @staticmethod is additionally decorated with another decorator, it is still treated as a static method:

from __future__ import annotations

def does_nothing[T](f: T) -> T:
    return f

class C:
    @staticmethod
    @does_nothing
    def f1(x: int) -> str:
        return "a"

    @does_nothing
    @staticmethod
    def f2(x: int) -> str:
        return "a"

reveal_type(C.f1(1))  # revealed: str
reveal_type(C().f1(1))  # revealed: str
reveal_type(C.f2(1))  # revealed: str
reveal_type(C().f2(1))  # revealed: str

When a @staticmethod is decorated with @contextmanager, accessing it from an instance should not bind self:

from contextlib import contextmanager
from collections.abc import Iterator

class D:
    @staticmethod
    @contextmanager
    def ctx(num: int) -> Iterator[int]:
        yield num

    def use_ctx(self) -> None:
        # Accessing via self should not bind self
        with self.ctx(10) as x:
            reveal_type(x)  # revealed: int

# Accessing via class works
reveal_type(D.ctx(5))  # revealed: _GeneratorContextManager[int, None, None]

# Accessing via instance should also work (no self-binding)
reveal_type(D().ctx(5))  # revealed: _GeneratorContextManager[int, None, None]

__new__

__new__ is an implicit @staticmethod; accessing it on an instance does not bind the cls argument:

from typing_extensions import Self

reveal_type(object.__new__)  # revealed: def __new__[Self](cls) -> Self
reveal_type(object().__new__)  # revealed: def __new__[Self](cls) -> Self
# revealed: Overload[[Self](cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = 0, /) -> Self, [Self](cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self]
reveal_type(int.__new__)
# revealed: Overload[[Self](cls, x: str | Buffer | SupportsInt | SupportsIndex | SupportsTrunc = 0, /) -> Self, [Self](cls, x: str | bytes | bytearray, /, base: SupportsIndex) -> Self]
reveal_type((42).__new__)

class X:
    def __init__(self, val: int): ...
    def make_another(self) -> Self:
        reveal_type(self.__new__)  # revealed: def __new__[Self](cls) -> Self
        return self.__new__(type(self))

Builtin functions and methods

Some builtin functions and methods are heavily special-cased by ty. This mdtest checks that various properties are understood correctly for these functions and methods.

import types
from typing import Callable
from ty_extensions import static_assert, RegularCallableTypeOf, is_assignable_to, TypeOf

def f(obj: type) -> None: ...

class MyClass:
    @property
    def my_property(self) -> int:
        return 42

    @my_property.setter
    def my_property(self, value: int | str) -> None: ...

static_assert(is_assignable_to(types.FunctionType, Callable))

# revealed: <wrapper-descriptor '__get__' of 'function' objects>
reveal_type(types.FunctionType.__get__)
static_assert(is_assignable_to(TypeOf[types.FunctionType.__get__], Callable))

# revealed: def f(obj: type) -> None
reveal_type(f)
static_assert(is_assignable_to(TypeOf[f], Callable))

# revealed: <method-wrapper '__get__' of function 'f'>
reveal_type(f.__get__)
static_assert(is_assignable_to(TypeOf[f.__get__], Callable))

# revealed: def __call__(self, *args: Any, **kwargs: Any) -> Any
reveal_type(types.FunctionType.__call__)
static_assert(is_assignable_to(TypeOf[types.FunctionType.__call__], Callable))

# revealed: <method-wrapper '__call__' of function 'f'>
reveal_type(f.__call__)
static_assert(is_assignable_to(TypeOf[f.__call__], Callable))

# revealed: <wrapper-descriptor '__get__' of 'property' objects>
reveal_type(property.__get__)
static_assert(is_assignable_to(TypeOf[property.__get__], Callable))

# revealed: property
reveal_type(MyClass.my_property)
static_assert(is_assignable_to(TypeOf[property], Callable))
static_assert(not is_assignable_to(TypeOf[MyClass.my_property], Callable))

# revealed: <method-wrapper '__get__' of property 'my_property'>
reveal_type(MyClass.my_property.__get__)
static_assert(is_assignable_to(TypeOf[MyClass.my_property.__get__], Callable))

# revealed: <wrapper-descriptor '__set__' of 'property' objects>
reveal_type(property.__set__)
static_assert(is_assignable_to(TypeOf[property.__set__], Callable))

# revealed: <method-wrapper '__set__' of property 'my_property'>
reveal_type(MyClass.my_property.__set__)
static_assert(is_assignable_to(TypeOf[MyClass.my_property.__set__], Callable))

# revealed: def startswith(self, prefix: str | tuple[str, ...], start: SupportsIndex | None = None, end: SupportsIndex | None = None, /) -> bool
reveal_type(str.startswith)
static_assert(is_assignable_to(TypeOf[str.startswith], Callable))

# revealed: <method-wrapper 'startswith' of string 'foo'>
reveal_type("foo".startswith)
static_assert(is_assignable_to(TypeOf["foo".startswith], Callable))

def _(
    a: RegularCallableTypeOf[types.FunctionType.__get__],
    b: RegularCallableTypeOf[f],
    c: RegularCallableTypeOf[f.__get__],
    d: RegularCallableTypeOf[types.FunctionType.__call__],
    e: RegularCallableTypeOf[f.__call__],
    f: RegularCallableTypeOf[property],
    g: RegularCallableTypeOf[property.__get__],
    h: RegularCallableTypeOf[MyClass.my_property.__get__],
    i: RegularCallableTypeOf[property.__set__],
    j: RegularCallableTypeOf[MyClass.my_property.__set__],
    k: RegularCallableTypeOf[str.startswith],
    l: RegularCallableTypeOf["foo".startswith],
):
    # revealed: Overload[(self: FunctionType, instance: None, owner: type, /) -> Unknown, (self: FunctionType, instance: object, owner: type | None = None, /) -> Unknown]
    reveal_type(a)

    # revealed: (obj: type) -> None
    reveal_type(b)

    # TODO: ideally this would have precise return types rather than `Unknown`
    # revealed: Overload[(instance: None, owner: type, /) -> Unknown, (instance: object, owner: type | None = None, /) -> Unknown]
    reveal_type(c)

    # revealed: (self, *args: Any, **kwargs: Any) -> Any
    reveal_type(d)

    # revealed: (obj: type) -> None
    reveal_type(e)

    # revealed: (fget: ((Any, /) -> Any) | None = None, fset: ((Any, Any, /) -> None) | None = None, fdel: ((Any, /) -> None) | None = None, doc: str | None = None) -> property
    reveal_type(f)

    # revealed: Overload[(self: property, instance: None, owner: type, /) -> Unknown, (self: property, instance: object, owner: type | None = None, /) -> Unknown]
    reveal_type(g)

    # TODO: ideally this would have precise return types rather than `Unknown`
    # revealed: Overload[(instance: None, owner: type, /) -> Unknown, (instance: object, owner: type | None = None, /) -> Unknown]
    reveal_type(h)

    # TODO: ideally this would have `-> None` rather than `-> Unknown`
    # revealed: (self: property, instance: object, value: object, /) -> Unknown
    reveal_type(i)

    # TODO: ideally this would have a more precise input type and `-> None` rather than `-> Unknown`
    # revealed: (instance: object, value: object, /) -> Unknown
    reveal_type(j)

    # revealed: (self, prefix: str | tuple[str, ...], start: SupportsIndex | None = None, end: SupportsIndex | None = None, /) -> bool
    reveal_type(k)

    # revealed: (prefix: str | tuple[str, ...], start: SupportsIndex | None = None, end: SupportsIndex | None = None, /) -> bool
    reveal_type(l)