improve your python code(8)

1. [] {} ().用列表解析器代替for遍历

理由：
高校

2. 函数传参既非传引用也非传值

a = 5   # 开辟一个内存存放5，将a这个标签贴在这个内存上b = a   # 将b这个标签也贴在刚才的那个内存上b = 7   # 开辟一个内存存放7，将b这个标签贴在这个内存上,刚才的那个b被覆盖。

3. *args,**kwargs

4. staticmethod和classmethod

首先要明白，什么是实例方法、静态方法和类方法：

class Demo(object):    def instance_method(self, your_para):        """        this is an instance_method        you should call it like the follow:        a = Demo()        a.instance_method(your_para)        plus: in python, we denote 'cls' as latent para of Class        while 'self' as latent para of the instance of the Class        :param your_para:         :return:         """        print("call instance_method and get:", your_para)    @classmethod    def class_method(cls, your_para):        """        this is a class_method        you can call it like the follow:        method1:        a = Demo()        a.class_method(your_para)        method2:        Demo.class_method        plus: in python, we denote 'cls' as latent para of Class        while 'self' as latent para of the instance of the Class        :param your_para:         :return:         """        print("call class_method and get:", your_para)    @staticmethod    def static_method(your_para):        """        this is a static_method and you can call it like the         methods of class_method        :param your_para:         :return:         """        print("call static_method and get:", your_para)

1. 虽然类方法在调用的时候没有显式声明cls，但实际上类本身是作为隐含参数传入的。这就像实例方法在调用的时候也没有显式声明self,但实际上实例本身是作为隐含参数传入的。
2. 对于静态函数，我们一般把与类无关也与实例无关的函数定义为静态函数。例如入口检查的函数就最好定义成静态函数。
3. 类方法的妙处：
   1，在继承中的作用：

class Fruit(object):    total = 0   # 这是一个类属性    @classmethod    def print_total(cls):        print('this is the ', cls, '.total:', cls.total, ' and its id: ', id(cls.total))    # cls是类本身，打印类属性total的值        print('this is the Fruit.total:', Fruit.total, 'and its id: ', id(Fruit.total))        print("=======================")    @classmethod    def set(cls, value):        cls.total = valueclass Apple(Fruit):    passclass Orange(Fruit):    passapp1 = Apple()app1.set(10)app1.print_total()Apple.print_total()Fruit.set(2)app1.print_total()Fruit.print_total()"""output:this is the  <class '__main__.Apple'> .total: 10  and its id:  1355201264this is the Fruit.total: 0 and its id:  1355200944=======================this is the  <class '__main__.Apple'> .total: 10  and its id:  1355201264this is the Fruit.total: 0 and its id:  1355200944=======================this is the  <class '__main__.Apple'> .total: 10  and its id:  1355201264this is the Fruit.total: 2 and its id:  1355201008=======================this is the  <class '__main__.Fruit'> .total: 2  and its id:  1355201008this is the Fruit.total: 2 and its id:  1355201008======================="""