Python装饰器之函数的装饰器

decorator

Decorators for Functions and Methods

1.函数实现装饰函数的装饰器（Function Decorators）

1.1函数不带参数

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def decorator(fun):
    def wrapper():
        print('into fun decorator')
        fun()
    return wrapper
@decorator
def echo():
    print('into echo')
echo()
# echo() => decorator(echo)() => wrapper()

1.2函数带参数

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def decorator(fun):
    def wrapper(*args, **kwargs):
        print('into fun decorator')
        print(*args, **kwargs)
        fun(*args, **kwargs)
    return wrapper
@decorator
def echo(name, age):
    print('into echo ' + name + ' ' + age)
echo('nike', '20')
# echo('nike', '20') => decorator(echo)('nike', '20') => wrapper('nike', '20')

1.3装饰器带参数

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def decorator(*o_args, **o_kwargs):
    print('into outer fun decorator')
    print(*o_args, **o_kwargs)
    def outer_wrapper(fun):
        def wrapper(*args, **kwargs):
            print('into fun decorator')
            print(*o_args, **o_kwargs)
            print(*args, **kwargs)
            fun(*args, **kwargs)
        return wrapper
    return outer_wrapper
@decorator('hi', 'decorator')
def echo(name, age):
    print('into echo ' + name + ' ' + age)
echo('nike', '20')
# echo('nike', '20') => decorator('hi', 'decorator')(echo)('nike', '20')
# => outer_wrapper(echo)('nike', '20') => wrapper('nike', '20')

1.4@functools.wraps

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import functools
def decorator(fun):
    @functools.wraps(fun)
    def wrapper():
        print('into fun decorator')
        fun()
    return wrapper
@decorator
def echo():
    print('into echo')
print(echo.__name__)

2.类实现装饰函数的装饰器（Class Decorators）

###2.1函数不带参数

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class Decorator:
    def __init__(self, fun):
        print('__init__')
        self.fun = fun
    def __call__(self):
        print('__call__')
        self.fun()
@Decorator
def echo():
    print('into echo')
echo()
echo()
# def echo() => Decorator.__init__(echo)
# echo() => Decorator.__call__()

2.2函数带参数

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class Decorator:
    def __init__(self, fun):
        print('__init__')
        print(fun)
        self.fun = fun
    def __call__(self, *args, **kwargs):
        print('__call__')
        print(args, kwargs)
        self.fun(*args, **kwargs)
@Decorator
def echo(name):
    print('into echo' + name)
echo('2')
echo('3')
# echo(2) = Decorator(echo)(2) = Decorator.__init__(echo).__call__(2)

2.3装饰器带参数

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class Decorator:
    def __init__(self, *args, **kwargs):
        print('__init__')
        print(args, kwargs)
    def __call__(self, fun):
        print('__call__')
        def wrapper(*args, **kwargs):
            print('into wrapper')
            fun(*args, **kwargs)
        return wrapper
@Decorator('1', '2')
def echo(name):
    print('into echo' + name)
echo('3')
echo('4')
# echo('2') = wrapper('2')
# echo('2') = Decorator('1')(echo)('2') = Decorator.__init__('1').__call__(echo).__call__('2')