python之装饰器进化

什么是装饰器：用于拓展原来函数功能的一种函数，目的是在不改变原函数名(或类名)的情况下，给函数增加新的

装饰器作用于最近的函数

在不修改 demo 函数的情况下，扩展 demo 功能，每次调用只能用 wrapper_demo

def demo():
    print('this is demo !')


def wrapper_demo(func):
    print('this is wrapper demo start !')
    func()
    print('this is wrapper demo end !')

wrapper_demo(demo)

在不修改 demo 调用方式的情况下，扩展 demo 功能

def demo():
    print('this is demo !')


def wrapper_demo(func):

    def inner():
        print('this is wrapper demo start !')

        func()

        print('this is wrapper demo end !')
    return inner

demo = wrapper_demo(demo)    # 每次调用都要写一遍
demo()

使用语法糖装饰函数，代替 demo =  wrapper_demo(demo)

def wrapper_demo(func):

    def inner():
        print('this is wrapper demo start !')

        func()

        print('this is wrapper demo end !')
    return inner


@wrapper_demo    # 代替 demo = wrapper_demo(demo)
def demo():
    print('this is demo !')


demo()

带 return 的 demo 函数

def wrapper_demo(func):

    def inner():
        print('this is wrapper demo start !')

        ret = func()

        print('this is wrapper demo end !')
        return ret
    return inner


@wrapper_demo    # 代替 demo = wrapper_demo(demo)
def demo():
    print('this is demo !')
    return 'Hello World'

ret = demo()
print(ret)

带参数的 demo，万能参数的装饰器

def wrapper_demo(func):

    def inner(*args, **kwargs):
        print('this is wrapper demo start !')

        ret = func(*args, **kwargs)

        print('this is wrapper demo end !')
        return ret
    return inner


@wrapper_demo
def demo1(name):
    print(f"{name} 进化！")
    return '进化形态---->暴龙兽！'


@wrapper_demo
def demo2(name, evolution_name):
    print(f"{name} 超进化！")
    return f"超进化形态---->{evolution_name}！"


ret = demo1('亚古兽')
print(ret)

print('-' * 20)

ret = demo2('暴龙兽', '机械暴龙兽')
print(ret)

多个装饰器

def wrapper_demo1(func):

    def inner(*args, **kwargs):
        print('-----进化 !')

        ret = func(*args, **kwargs)

        print('-----超级火焰弹 !')
        return ret
    return inner


def wrapper_demo2(func):

    def inner(*args, **kwargs):
        print('+++++超进化开始 !')

        ret = func(*args, **kwargs)

        print('+++++盖亚能量炮 !')
        return ret
    return inner


def wrapper_demo3(func):

    def inner(*args, **kwargs):
        print('=====究极进化开始 !')

        ret = func(*args, **kwargs)

        print('=====战斗龙卷风 !')
        return ret
    return inner


def demo1(name, big_recruit):
    print(f"究极形态---->{name} ！")
    return f"大招---->{big_recruit}！"


@wrapper_demo1    # wrapper_demo1(wrapper_demo2(wrapper_demo3(demo2)))
@wrapper_demo2    # wrapper_demo2(wrapper_demo3(demo2))
@wrapper_demo3    # wrapper_demo3(demo2)
def demo2(name, evolution_name):
    print(f"{name} 究极进化！")
    return f"究极进化形态---->{evolution_name}！"


ret = demo2('机械暴龙兽', '战斗暴龙兽')
print(ret)

print('-' * 50)

ret = wrapper_demo1(wrapper_demo2(wrapper_demo3(demo1)))('战斗暴龙兽', '战斗龙卷风')
print(ret)

不修改 demo.__name 

from functools import wraps

def wrapper_demo1(func):
    @wraps(func)    # 不修改 demo.__name__
    def inner(*args, **kwargs):
        print('-----进化 !')

        ret = func(*args, **kwargs)

        print('-----超级火焰弹 !')
        return ret
    return inner


@wrapper_demo1
def demo2(name, evolution_name):
    print(f"{name} 究极进化！")
    return f"究极进化形态---->{evolution_name}！"


print(demo2.__name__)

 带参数的装饰器

name1 = '加布兽'
name2 = '加鲁鲁兽'

def evolution(name, new_name):
    def wrapper_demo(func):

        def inner(*args, **kwargs):
            print(f"{name} 进化 {new_name} !")

            ret = func(*args, **kwargs)

            print(f"极零冷冻波 !")
            return ret
        return inner

    return wrapper_demo


@evolution(name1, name2)
def demo(name, evolution_name):
    print(f"{name} 究极进化---->{evolution_name} ！")


demo(name2, '钢铁加鲁鲁兽')