class Person():
  def say(self):
    pass
class Student(Person):
  def say(self):
    print("i am student")

import abc
class Person(metaclass=abc.ABCMeta):
  @abc.abstractmethod
  def say(self):
    pass
class Student(Person):
  def say(self):
    print("i am student")
s = Student()
s.say()

class Student():
  pass
def say(self):
  print("i am say")
s = Student()
s.say=say
s.say(9)

from types import MethodType
class Student():
  pass
def say(self):
  print("i am say")
s = Student()
s.say=MethodType(say,Student)
s.say()

# 类名一般为MetaClass结尾
class StudentMetaClass(type):
  def __new__(cls, *args, **kwargs):
    print("元类")
    return type.__new__(cls, *args, **kwargs)
class Teacher(object, metaclass=StudentMetaClass):
  pass
t = Teacher()
print(t.__dict__)

from abc import ABCMeta, abstractmethod
#抽象类
class Headers(object):
  __metaclass__ = ABCMeta
  def __init__(self):
    self.headers = ''
  @abstractmethod
  def _getBaiduHeaders(self):pass
  def __str__(self):
    return str(self.headers)
  def __repr__(self):
    return repr(self.headers)
#实现类
class BaiduHeaders(Headers):
  def __init__(self, url, username, password):
    self.url = url
    self.headers = self._getBaiduHeaders(username, password)
  def _getBaiduHeaders(self, username, password):
    client = GLOBAL_SUDS_CLIENT.Client(self.url)
    headers = client.factory.create('ns0:AuthHeader')
    headers.username = username
    headers.password = password
    headers.token = _baidu_headers['token']
    return headers