Python如何获取用property.setter包装的方法的__qualname__

Question

我有一个实例属性，我使用 Python 的 property 装饰器创建了一个属性。

然后我使用装饰器 @property_name.setter 为该属性创建了一个 setter。

我怎样才能得到原始方法定义的__qualname__，用@property.setter装饰？

---

我看过的地方

• Python: __qualname__ of function with decorator
  • 我不认为property 使用@functools.wraps()
• Python @property.setter
  • 我意识到property 实际上是一个descriptor
• Decorating a class method after @property
  • 告诉我我可能想使用__get__，但我不知道语法

---

示例代码

这是写在Python 3.6。

#!/usr/bin/env python3


def print_qualname():
    """Wraps a method, printing its qualified name."""

    def print_qualname_decorator(func):
        # print(f"func = {func} and dir(): {dir(func)}")
        if hasattr(func, "__qualname__"):
            print(f"Qualified name = {func.__qualname__}.")
        else:
            print("Doesn't have qualified name.")

    return print_qualname_decorator


class SomeClass:

    def __init__(self):
        self._some_attr = 0
        self._another_attr = 0

    @property
    def some_attr(self) -> int:
        return self._some_attr

    @print_qualname()
    @some_attr.setter
    def some_attr(self, val: int) -> None:
        self._some_attr = val

    @print_qualname()
    def get_another_attr(self) -> int:
        return self._another_attr

输出：

Doesn't have qualified name.
Qualified name = SomeClass.get_another_attr.

如何从 print_qualname 装饰器中获取 __qualname__ 的 some_attr？换句话说，如何输出SomeClass.some_attr？

Answer 1

您可以为 setter 翻转装饰器的顺序。注意我已经调整了print_qualname_decorator 来调用底层函数并返回它（否则setter 将不会执行）。

from functools import wraps

def print_qualname(func):
    """Wraps a method, printing its qualified name."""
    @wraps(func)
    def print_qualname_decorator(*args):
        if hasattr(func, "__qualname__"):
            print(f"Qualified name = {func.__qualname__}.")
        else:
            print("Doesn't have qualified name.")
        return func(*args)
    return print_qualname_decorator


class SomeClass:

    def __init__(self):
        self._some_attr = 0
        self._another_attr = 0

    @property
    def some_attr(self) -> int:
        return self._some_attr

    @some_attr.setter
    @print_qualname
    def some_attr(self, val: int) -> None:
        self._some_attr = val

    @print_qualname
    def get_another_attr(self) -> int:
        return self._another_attr

使用

In [46]: foo = SomeClass()                                               

In [47]: foo.get_another_attr()                                          
Qualified name = SomeClass.get_another_attr.
Out[47]: 0

In [48]: foo.some_attr = 5                                               
Qualified name = SomeClass.some_attr.

In [49]: foo._some_attr                                                  
Out[49]: 5