python 函数装饰器

# 使用一个函数来装饰另一个函数，不使用@

def a_new_decorator(a_func):

    def wrapTheFunc():
        print("Do sth. before a_func()")

        a_func()

        print("Do sth. after a_func()")

    return wrapTheFunc


def a_func_requiring_decoration():
    print("I need some decoration")

a_func_requiring_decoration = a_new_decorator(a_func_requiring_decoration)

a_func_requiring_decoration()

# 输出如下：
# Do sth. before a_func()
# I need some decoration
# Do sth. after a_func()

# 使用@来运行上面的代码

def a_new_decorator(a_func):

    def wrapTheFunc():
        print("Do sth. before a_func()")

        a_func()

        print("Do sth. after a_func()")

    return wrapTheFunc

@a_new_decorator
def a_func_requiring_decoration():
    print("I need some decoration")

# a_func_requiring_decoration = a_new_decorator(a_func_requiring_decoration)

a_func_requiring_decoration()

the @a_new_decorator is a just a short way of saying:
a_func_requiring_decoration = a_new_decorator(a_func_requiring_decoration)

# 希望print(xx.__name__)的结果是xx，而不是wrapTheFunc
# 使用functools.wraps来解决此问题

from functools import wraps


def a_new_decorator(a_func):
    @wraps(a_func)
    def wrapTheFunc():
        print("Do sth. before a_func()")

        a_func()

        print("Do sth. after a_func()")

    return wrapTheFunc

@a_new_decorator
def a_func_requiring_decoration():
    print("I need some decoration")

# a_func_requiring_decoration = a_new_decorator(a_func_requiring_decoration)

a_func_requiring_decoration()

print(a_func_requiring_decoration.__name__)

注意：@wraps接受一个函数来进行装饰，并加入了复制函数名称、注释文档、参数列表等等的功能。这可以让我们在装饰器里面访问在装饰之前的函数的属性。