Python中类的__init__继承

Python中类的__init__继承

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 概念：

　定义父类

In [10]: class Person:
   ....:     def __init__(self,name,age,sex):
   ....:         self.name = name
   ....:         self.age = age
   ....:         self.sex = sex
   ....:     def get_name(self):
   ....:         print('name:',self.name)
   ....:  
In [11]: Bob = Person('Bob',18,'男')

In [12]: Bob.get_name()
name: Bob

【1】子类不重写__init__，实例化子类时，会自动调用父类定义的__init__

In [13]: class Person_child(Person):
   ....:     def get_name(self):
   ....:         print('name:',self.name)
   ....:         

In [14]: child = Person_child('baby',2,'男')

In [15]: child.get_name()
name: baby

【2】另一种的验证方式

class Person:
    def __init__(self,name,age):
        self.name = 'Bob'
        self.age = 18

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

class Student(Person):
    def get_name(self):
        print('name:',self.name)    

Kevin = Student('Kevin',12)
print('-------------------------')
print(Kevin.name)    
print(Kevin.age)    
print('-------------------------')

output
-------------------------
Bob
18
-------------------------

【3】但重写了__init__时，实例化子类，就不会调用父类已经定义的__init__

In [17]: class Person_child(Person):
   ....:     def __init__(self,name,age,sex):
   ....:         self.name = name
   ....:         self.age = age
   ....:         self.sex = sex
   ....:     def get_name(self):
   ....:         print('child_name:',self.name)
   ....:         

In [18]: K = Person_child('Kevin',16,'男')

In [19]: K.get_name()
child_name: Kevin

【4】为了能使用或扩展父类的行为，最好显示调用父类的__init__方法

class Person:
    def __init__(self,name,age):
        self.name = 'Bob'
        self.age = 18

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

class Student(Person):
    def __init__(self,name,age,sex):
        super(Student,self).__init__(name,age)
        self.sex = sex

    def get_detail(self):
        print('详细信息：',self.name,'---',self.age,'---',self.sex)

        

Kevin = Student('Kevin',12,'男')
print('-------------------------')
print(Kevin.name)    
print(Kevin.age)    
print(Kevin.sex)
print(Kevin.get_detail())    
print('-------------------------')

# output
-------------------------
Bob
18
男
详细信息： Bob --- 18 --- 男
None
-------------------------

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