Python 访问修饰符作为装饰器

Question

在Python中，

_name

是受保护的，而

__name

是私有的

是否可以使用装饰器为类实现访问修饰符？怎么办？

功能应该类似于下面的代码：

class A:
    
    def public_func(self):
        self.protected_func()    # Runs without warning and error    (Because is called in the owner class)
        self.private_func()      # Runs without warning and error    (Because is called in the owner class)
    
    @protected
    def protected_func(self):
        print('protected is running')
        self.private_func()      # Runs without warning and error    (Because is called in the owner class)
    
    @private
    def private_func(self):
        print(f'private is running')


a = A()
a.public_func()                  # Runs without any warning and error            (Because has no access modifier)
a.protected_func()               # Runs with protected warning
a.private_func()                 # Raises Exception

这个问题的想法是可访问的私有函数，如下所示：

class A:

    def __private_func(self):
        print('private is running')

a = A()
a._A__private_function()

如果我们用

private

定义

decorator

，那么就不必用

__name

定义它。 所以

_A__private_function

将不存在，并且私有函数在所有者类之外确实不是不可访问的。

Answer 1

你可以这样尝试

def protected(func):
    def wrapper(self, *args, **kwargs):
        if not func.__name__.startswith('_'):
            print(f"Warning: {func.__name__} is not marked as protected.")
        return func(self, *args, **kwargs)
    return wrapper

def private(func):
    def wrapper(self, *args, **kwargs):
        if not func.__name__.startswith('__'):
            raise Exception(f"{func.__name__} is private and cannot be accessed directly.")
        return func(self, *args, **kwargs)
    return wrapper

class A:
    
    def public_func(self):
        self.protected_func()
        self.private_func()
    
    @protected
    def protected_func(self):
        print('protected is running')
        self.private_func()
    
    @private
    def private_func(self):
        print(f'private is running')

a = A()
a.public_func()      # Runs without any warning or error (Because it has no access modifier)
a.protected_func()   # Runs with a protected warning
a.private_func()     # Raises Exception

# Accessing private function using name mangling
a._A__private_func()  # Runs without any warning or error