新式類vs經(jīng)典類，類的多態(tài)實(shí)現(xiàn)

```# 
# 經(jīng)典類VS新式類
class person(object): #這就是新式類
    pass
    #super(Teacher,self).__init__(name,age,sex) # 新式類寫法

class Person: #這就是經(jīng)典類
    pass
    #School.__init__(self,name,age,sex) #經(jīng)典類寫法

## 新式類（先從左往右找，B沒(méi)有就找C，C沒(méi)有就找A！這種查詢叫廣度查詢，先查完B,C這一層，再去查A層）
class A(object):
    def __init__(self):
        self.n="A"

class B(A):
    pass
    #def __init__(self):
    #self.n="B"

class C(A):
    def __init__(self):
        self.n="C"

class D(B,C):
    pass
    # def __init__(self):
    #     self.n="D"
d=D()
print(d.n)

## 經(jīng)典類（經(jīng)典類在python2中先找B，B沒(méi)有就去找A！這叫深度查詢，如果A里沒(méi)找到就去找C）（新式類和經(jīng)典類在pythin3中都是廣度查詢！）
class A:
    def __init__(self):
        self.n="A"

class B(A):
    #pass
    #def __init__(self):
       #self.n="B"

class C(A):
   #pass
    def __init__(self):
        self.n="C"

class D(B,C):
    pass
    #def __init__(self):
    #self.n="D"
d=D()
print(d.n)

# 多態(tài)
class Animal(object):
    def __init__(self, name):  # Constructor of the class
        self.name = name

    def talk(self):  # Abstract method, defined by convention only
        raise NotImplementedError("Subclass must implement abstract method")

class Cat(Animal):
    def talk(self): #重新定義talk
        print('%s: 喵喵喵!' % self.name)

class Dog(Animal):
    def talk(self): #重新定義talk
        print('%s: 汪！汪！汪！' % self.name)

def func(obj):  # 一個(gè)接口，多種形態(tài)（傳入不同的實(shí)例，調(diào)用的接口都是talk，單表達(dá)方式不同）
    obj.talk()

c1 = Cat('小晴')
d1 = Dog('李磊')
func(c1)
func(d1)