PyCharm中自定义类装饰属性的类型检查兼容性指南

from functools import cached_property
from collections.abc import Callable
from typing import TypeVar, Generic, Any, overload, Union

T = TypeVar("T")

class result_property(cached_property, Generic[T]):
    """
    一个自定义的泛型属性描述符，继承自 cached_property。
    """
    def __init__(self, func: Callable[[Any], T]) -> None:
        super().__init__(func)

    def __set_name__(self, owner: type[Any], name: str) -> None:
        super().__set_name__(owner, name)

    @overload
    def __get__(self, instance: None, owner: Union[type[Any], None] = None) -> 'result_property[T]': ...
    @overload
    def __get__(self, instance: object, owner: Union[type[Any], None] = None) -> T: ...

    def __get__(self, instance, owner=None):
        return super().__get__(instance, owner)

def func_str(s: str) -> None:
    """接受字符串参数的函数。"""
    print(s)

class Foo:
    @result_property
    def prop_int(self) -> int:
        """一个返回整数的缓存属性。"""
        return 1

# 实例化并尝试将整数属性传递给期望字符串的函数
foo = Foo()
func_str(foo.prop_int)

tmp.py:38: error: Argument 1 to "func_str" has incompatible type "int"; expected "str"  [arg-type]
Found 1 error in 1 file (checked 1 source file)

# 这是一个简化的、名称为 cached_property 的函数，不具备描述符行为
def cached_property(func):
    def foo(self):
        pass # 实际功能无关紧要
    return foo

def func_str(s: str) -> None:
    print(s)

class Foo:
    @cached_property
    def prop_int(self) -> int:
        return 1

foo = Foo()
func_str(foo.prop_int) # PyCharm 会在此处抱怨：期望类型 'str'，得到 'int'

import functools
from collections.abc import Callable
from typing import TypeVar, Generic, Any, overload, Union

T = TypeVar("T")

# 将自定义描述符的名称改为 cached_property
class cached_property(functools.cached_property, Generic[T]):
    """
    通过重命名为 cached_property，使 PyCharm 能够正确推断类型。
    """
    def __init__(self, func: Callable[[Any], T]) -> None:
        super().__init__(func)

    def __set_name__(self, owner: type[Any], name: str) -> None:
        super().__set_name__(owner, name)

    @overload
    def __get__(self, instance: None, owner: Union[type[Any], None] = None) -> 'cached_property[T]': ...
    @overload
    def __get__(self, instance: object, owner: Union[type[Any], None] = None) -> T: ...

    def __get__(self, instance, owner=None):
        return super().__get__(instance, owner)

def func_str(s: str) -> None:
    print(s)

class Foo:
    @cached_property # 现在使用我们重命名后的描述符
    def prop_int(self) -> int:
        return 1

foo = Foo()
func_str(foo.prop_int) # PyCharm 会在此处正确抱怨：期望类型 'str'，得到 'int'