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装饰器
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函数修饰器
============================

修饰带有返回值的函数
----------------------------

修改返回值::

    def w_test(func):
        def inner():
            print('w_test inner called start')
            str = func()
            print('w_test inner called end')
            return str.lower()
        return inner
    @w_test
    def test():
        print('this is test fun')
        return 'HELLO'
    ret = test()
    print('ret value is %s' % ret)


装饰器带参数，函数不带参数::

    def func_args(pre='xiaoqiang'):
        def w_test_log(func):
            def inner():
                print('...记录日志...visitor is %s' % pre)
                func()
            return inner
        return w_test_log
    # 带有参数的装饰器能够起到在运行时，有不同的功能
    # 先执行func_args('wangcai')，返回w_test_log函数的引用
    # @w_test_log
    # 使用@w_test_log对test_log进行装饰
    @func_args('wangcai')
    def test_log():
        print('this is test log')
    test_log()

修饰类
------------------------------

.. code-block:: python

    def register():

        def _mock_wrapper(_class):
            return _class
        return _mock_wrapper


    class A:
        def __init__(self):
            pass

        def q(self):
            print(333)

        @classmethod
        def t(cls):
            print(1111)


    @register()  # 必须带括号，不带括号是当作函数使用
    class B(A):
        def t2(self):
            print(2222)

用类方法的装饰器
================================================

.. code-block::

    class Docker:
        subcommands = []

        @classmethod
        def subcommand(cls, sub_class):
            cls.subcommands.append(sub_class)
            del sub_class

    @Docker.subcommand
    class Search:
        ...