python 装饰器（七）：装饰器实例（四）类装饰器装饰类以及类方法

类装饰器装饰类方法

不带参数

from functools import wraps
import types
class CatchException:

    def __init__(self,origin_func):
        wraps(origin_func)(self)

    def __get__(self, instance, cls):
        if instance is None:
            return self
        else:
            return types.MethodType(self, instance)
    #在这里，__get__() 的目的是创建一个绑定方法对象 (最终会给这个方法传递self参数)。

    def __call__(self,*args, **kwargs):

        try:
            print('haha')
            print(self.__wrapped__)
            return self.__wrapped__(*args, **kwargs)
        except Exception as e:
            print(e)
            return 'an Exception raised.'

class Test(object):
    def __init__(self):
        pass

    def revive(self):
        print('revive from exception.')
        # do something to restore

    @CatchException
    def read_value(self):
        print('here I will do something')
        # do something.
        #
    #相当于read_value = CatchException(read_value)  

if __name__ == '__main__':
    t = Test()
    print(Test.read_value)#结果 <__main__.CatchException object at 0x00000188516A9608>
    print(t.read_value)#结果 <bound method Test.read_value of <__main__.Test object at 0x00000188516A9648>>
    print(Test.read_value.__get__(t,Test)) #结果 <bound method Test.read_value of <__main__.Test object at 0x00000188516A9648>>
    t.read_value() #t.read_value 相当于 Test.read_value.__get__(t,Test),返回值为types.MethodType(CatchException(read_value), t)
                   #types.MethodType(CatchException(read_value), t) 相当于执行了将CatchException(read_value)实例绑定到t上
                   #则t.read_value()相当于types.MethodType(CatchException(read_value), t)()

带参数

class CatchException:

    def __init__(self,level):
        self.level = level

    def __call__(self,origin_func):
        def wrapper(origin_func_self,*args, **kwargs):
            print(self.level)
            try:
                u = origin_func(origin_func_self,*args, **kwargs)
                return u
            except Exception as e:
                origin_func_self.revive() #不用顾虑，直接调用原来的类的方法
                print(e)
                return 'an Exception raised.'
        return wrapper

class Test(object):
    def __init__(self):
        pass
    def revive(self):
        print('revive from exception.')
        # do something to restore
    @CatchException(level='error')
    def read_value(self):
        print('here I will do something.')
        # do something.
        # 

if __name__ == '__main__':
    t = Test()
    t.read_value()