理解解码器

Question

我试图理解Decorator，并对下面的代码感到有点困惑：

def smart_divide(func):
    def inner(a,b):
        print("I am going to divide",a,"and",b)
        if b == 0:
            print("Whoops! cannot divide")
            return

        return func(a,b) #In understand everything upto this point. How come when the function
                         #is called here there is no Error as we are still diving 2 by 0?
    return inner

@smart_divide
def divide(a,b):
    return a/b

print divide(2,0)

谢谢

Answer 1

为什么当函数在这里被调用时没有错误，因为我们仍然是2乘0？

如果b为零，则修饰函数将在前面返回：

if b == 0:
    print("Whoops! cannot divide")
    return

而零的除法永远不会被执行。相反，函数隐式返回None (如果您问我，这是一个有点奇怪的选择)。