class Student(object):

    pass

def set_score(self, score):

    self.score = score

Student.set_score = set_score #动态给类增加方法

s = Student()

s.set_score('dasheng')

print(s.score) #dasheng 

class Student(object):

    __slots__ = ('name', 'age') # 用tuple定义允许绑定的属性名称

#使用__slots__要注意，__slots__定义的属性仅对当前类实例起作用，对继承的子类是不起作用的：

#除非在子类中也定义__slots__，这样，子类实例允许定义的属性就是自身的__slots__加上父类的__slots__。

class Student(object):

    @property #可读

    def birth(self):

        return self._birth

    @birth.setter #可写

    def birth(self, value):

        self._birth = value

    @property

    def age(self): #可读，由于没有age.setter方法，表示只读

        return 2015 - self._birth

s = Student()

s.birth = 2011 #设置值

print(s.birth)  #获取值

class MyTCPServer(TCPServer, ForkingMixIn):

    pass

__str__(self) 或 __repr__() #让打印对象更好看

__iter__(self) #用于for ... in循环

def __iter__(self):

        return self # 实例本身就是迭代对象，故返回自己

__getitem__ #取下标 Fib()[5]

    def __getitem__(self, n):

        a, b = 1, 1

        for x in range(n):

            a, b = b, a + b

        return a

__getattr__() #当调用不存在的属性时，会试图调用__getattr__(self, 'score')来尝试获得属性

     def __getattr__(self, attr):

        if attr=='age':

            return lambda: 25    

__call__ #直接对实例进行调用

#通过callable()函数，我们就可以判断一个对象是否是“可调用”对象

from enum import Enum

Month = Enum('Month', ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))

for name, member in Month.__members__.items():

    print(name, '=>', member, ',', member.value)

from enum import Enum, unique

@unique

class Weekday(Enum):

    Sun=0

    Mon = 1,

    Tue = 2

day1 = Weekday.Mon

print(day1 == Weekday.Tue)#False

print(day1)#print(day1)

print(day1.value)  #print(day1)

def fn(self, name='word'):

    print('hello %s' % name)

Hello = type('Hello', (object,), dict(hello=fn)) # 创建Hello class

print(type(Hello)) #<class 'type'>

h = Hello()

print(type(h)) #<class '__main__.Hello'>

class ListMetaclass(type):

    def __new__(cls, name, bases, attrs):

        attrs['add'] = lambda self, value: self.append(value)

        return type.__new__(cls, name, bases, attrs)

class MyList(list, metaclass=ListMetaclass):

    pass

__new__()方法接收到的参数依次是：

1.当前准备创建的类的对象；

2.类的名字；

3.类继承的父类集合；

4.类的方法集合。