python 装饰器

import functools


def log(func):
    def wrapper(*args,**kw):
        print("call %s()"%func.__name__)
        return func(*args, **kw)
    return wrapper

@log    # 在执行处，相当于 now = log(now)
def now():
    print("now is now")

# 带参数的装饰器
def log2(text):
    def decorator(func):
        def wrapper(*args, **kw):
            print("%s %s():" % (text,func.__name__))
            return func(*args, **kw)
        return wrapper
    return decorator


@log2("excute")
def now2():
    print("now is now")

def log3(func):
    @functools.wraps(func) # 用于保留被装饰函数的元信息（如函数名、文档字符串等）
    def wrapper(*args, **kw):
        print("call %s():"%func.__name__)
        return func(*args,**kw)
    return wrapper

@ log3
def now3():
    print('now3 is now.')


def log4(text):
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kw):
            print('%s %s():'%(text, func.__name__))
            return func(*args, **kw)
        return wrapper
    return decorator

@log4('excute')
def now4():
    print('now4 is now.')



if __name__ == '__main__':
    # now = log(now)
    now()
    # now2 = log2('excute')(now2)
    now2()
    print(now2.__name__)

    now3()
    print(now3.__name__)

    # now4 = log4('excute')(now4)
    now4()
    print(now4.__name__)

    int2 = functools.partial(int,base = 2) # 将二进制数字转换为十进制数字
    print(int2('100'))

    max2 = functools.partial(max, 10)
    # 固定参数，求最大数
    print(max2(5, 6, 7))  # 相当于 args = (10,5,6,7)
    # max(*args)

输出：

call now()
now is now
excute now2():
now is now
wrapper
call now3():
now3 is now.
now3
excute now4():
now4 is now.
now4
4
10