浅谈Python中的继承

class Animal(object):

  def func(self):
    print("Animal.func")


class Dog(Animal):

  def func(self):
    print('Dog.func')


class Cat(Animal):
  """ No func~ """


print(Animal.func)  # <function Animal.func at 0x103f79620>
print(Cat.func)  # <function Animal.func at 0x103f79620>
print(Dog.func)  # <function Dog.func at 0x104073510>

class Animal(object):

  def tell(self):
    print('self.name:%s Animal.name %s ' % (id(self.name), id(Animal.name)))

  name = 'Animal'


class Cat(Animal):
  """ No func~ """

  def tell(self):
    super().tell()
    print('self.name %s Cat.name %s '% (id(self.name), id(Cat.name)))

cat = Cat()
cat.tell()
cat.name = 'django'
cat.tell()

# self.name:4473398472 Animal.name 4473398472 
# self.name 4473398472 Cat.name 4473398472 
# self.name:4474859736 Animal.name 4473398472 
# self.name 4474859736 Cat.name 4473398472 

class MyClass(object):
  """
  A simple example class
  """
  MyClassName = 'MyClass'
  name = 'MyClass'

  def func(self):
    print("This is {}".format(self.__class__.name))

  def get_name(self):
    print(self.name)

class MySonClass(MyClass):

  MySonClass = 'MySonClass'
  name = 'MySonClass' # 属性的重写

  def get_name(self):
    super().get_name()
    print('我重写了父类的get_name方法，上面是父类的方法，我来自子类！')


person1 = MyClass()
person2 = MySonClass()

person1.func()
person2.func()  # 方法的实现继承 自己没有，会直接调用父类的方法。但是使用的属性还是自己的。
print('*'*40)
person1.get_name()
person2.get_name()  # 方法的接口继承，在子类中重写了这个方法。


# 结果	
#------------------------------ 
# This is MyClass
# This is MySonClass
# ****************************************
# MyClass
# MySonClass
# 我重写了父类的get_name方法，上面是父类的方法，我来自子类！

class A(object):
  m = 'a'
class B(A):
  m = 'b'
class C(A):
  m = 'c'
class D(B,C):
  # m = 'd'
  pass
x = D()
print(x.m)

# D 的实例化对象如果获取 m 属性会优先的寻找自己的命名空间，查找顺序为 D -> B -> C -> A

# 钻石继承中的 重复调用问题
# 注意 继承的查找顺序～ 使用super()将按照 mro 顺序执行

class Grand(object):
  def __init__(self, name):
    self.name = name
    print("class Grand ")


class SonLeft(Grand):
  def __init__(self, age, name):
    self.age = age
    Grand.__init__(self, name) # 注释调 跑一跑 看一看
    # super().__init__(age, name)
    print("class SonLeft")


class SonRight(Grand):
  def __init__(self, gender, name):
    self.gender = gender
    Grand.__init__(self, name) # 注释调 跑一跑 看一看
    # super().__init__(name)
    print("class SonRight")


class GrandSon(SonLeft, SonRight):
  def __init__(self, name, age, gender):
    # super().__init__(age, name)
    SonLeft.__init__(self, age, name) # 注释调 跑一跑 看一看
    SonRight.__init__(self, gender, name) # 注释调 跑一跑 看一看
    self.gender = gender

grand_son = GrandSon("Monkey", 18, "男")