具有函数计数器变量的 Python 装饰器类

Question

我在 Python 中有一个类，我需要将其用作装饰器类，但我想在调用它时计算一些东西:

class SomeClass:

    counter = 0

    @staticmethod
    def some_function(a):
        """
        -----------------------
        Does something
        -----------------------
        """
        SomeClass.counter += 1
        a = a * a
        return a

调用后:

a = new_var.some_function(a) 

然后如何从我的装饰器类中获取计数器值？

Answer 1

您向我们展示的类不是装饰器——它只是一个类。访问柜台就这么简单

SomeClass.counter
# current counter value

让您的类成为真正的装饰器并不难——不过，我会将其重命名为Counter。

class Counter:
    """
    Count the number of calls made to the wrapped function.
    """
    def __init__(self, func):
        self.counter = 0
        self.func = func
    def __call__(self, *args, **kwds):
        self.counter += 1
        return self.func(*args, **kwds)

@Counter
def square(n):
    return n * n

并在使用中:

square(3)
# 9
square(7)
# 41
square(11)
# 121

square.counter
# 3

注意:这是一个非常简单的装饰器，一个副作用是包装函数的签名丢失。

展开的签名:

Help on function square in module __main__:
square(n)

封装的签名:

Help on instance of Counter in module __main__:
class Counter
 |  Count the number of calls made to the wrapped function.
 |  
 |  Methods defined here:
 |  
 |  __call__(self, *args, **kwds)
 |  
 |  __init__(self, func)