python decorator 用法

https://www.zhihu.com/question/31265857
http://www.cnblogs.com/huxi/archive/2011/03/01/1967600.html

方法装饰器

def decorator(Func):
    def new_Func(a, b):
        print 'input:', a, b
        return Func(a, b)
    return new_Func

@decorator
def square_sum(a, b):
    return a**2 + b**2

@decorator
def square_diff(a, b):
    return a**2 - b**2

print square_sum(3, 4)
print square_diff(3, 4)

# output
input:  3 4
25
input:  3 4
-7

类装饰器

def decorator(Class):
    class new_Class:
        def __init__(self, age):
            self.total_display  = 0
            self.wrapped = Class(age)

        def display(self):
            self.total_display += 1
            print("total display", self.total_display)
            self.wrapped.display()

    return new_Class

@decorator
class Bird(object):
    def __init__(self, age):
        self.age = age

    def display(self):
        print("My age is", self.age)

eagleLord = Bird(5)
for i in range(3):
    eagleLord.display()

# output
('total display', 1)
('My age is', 5)
('total display', 2)
('My age is', 5)
('total display', 3)
('My age is', 5)