Python装饰器

什么是装饰器？

• 在不改变原来代码的基础上，修改代码的逻辑
• 本质就是一个高阶函数
• 语法糖是@
• 分类
  • 函数装饰器：定义一个函数当做装饰器
  • 类装饰器：定义一个类当做装饰器
• 装饰器可以修饰普通方法，类方法，类...
• 装饰器可以叠加使用

函数装饰器

• 装饰器本身不带参数

def decorator(func):
    def _decorator(*args, **kwargs):
        print('decorator called, start!')
        ret = func(*args, **kwargs)
        print('decorator called, end!')
        return ret
    return _decorator

@decorator
def test(data):
    print('test : %s' % data)

test('ok')

• 装饰器本身带参数

def decorator(*args, **kwargs):
    print(args[0])
    print(kwargs['one'])
    def _decorator(func):
        def __decorator(*args, **kwargs):
            print('decorator called, start!')
            ret = func(*args, **kwargs)
            print('decorator called, end!')
            return ret
        return __decorator
    return _decorator

@decorator('x', one = 'a')
def test(data):
    print('test : %s' % data)

test('ok')

类装饰器

• 类装饰器本身不带参数

class decorator:
    def __init__(self, func):
        self.func = func

    def __call__(self, *args, **kwargs):
        print('decorator called, start!')
        ret = self.func(*args, **kwargs)
        print('decorator called, end!')
        return ret

@decorator
def test(data):
    print('test : %s' % data)

test('ok')

• 类装饰器本身带参数

class decorator:
    def __init__(self, x):
        self.x = x

    def __call__(self, func):
        print(self.x)
        def _dectorator(*args, **kwargs):
            print('decorator called, start!')
            ret = func(*args, **kwargs)
            print('decorator called, end!')
            return ret
        return _dectorator

@decorator('a')
def test(data):
    print('test : %s' % data)

test('ok')