简明python教程七----面向对象的编程（下）

Posted 2020-08-31

继承：类之间的类型和子类型关系

代码重用：SchoolMember类被称为 基本类或超类，而Teacher和Student类被称为导出类或者子类

#!/usr/bin/python
#Filename:Inherit.py

class SchoolMember:
    ‘Represents any school member.‘
    def __init__(self,name,age):
        self.name = name
        self.age = age
        print ‘(Initialized SchoolMember:%s)‘ %self.name

    def tell(self):
        ‘Tell my details.‘
        print ‘Name:"%s" Age:"%s"‘%(self.name,self.age)

class Teacher(SchoolMember):
    ‘Represents a teacher.‘
    def __init__(self,name,age,salary):
        SchoolMember.__init__(self,name,age)
        self.salary = salary
        print ‘(Initialized Teacher:%s)‘ %self.name

    def tell(self):
        SchoolMember.tell(self)
        print ‘Salary: "%d"‘%self.salary

class Student(SchoolMember):
    ‘Represents a student.‘
    def __init__(self,name,age,marks):
        SchoolMember.__init__(self,name,age)
        self.marks=marks
        print ‘(Initialized Student:%s)‘%self.name

    def tell(self):
        SchoolMember.tell(self)
        print ‘Marks:"%d"‘%self.marks


t=Teacher(‘Mrs.Shrividya‘,40,30000)
s=Student(‘Swaroop‘,22,75)

print #prints a blank line

members = [t,s]
for member in members:
    member.tell()

结果：

(Initialized SchoolMember:Mrs.Shrividya)
(Initialized Teacher:Mrs.Shrividya)
(Initialized SchoolMember:Swaroop)
(Initialized Student:Swaroop)

Name:"Mrs.Shrividya" Age:"40"
Salary: "30000"
Name:"Swaroop" Age:"22"
Marks:"75"

注意：为了使用继承，把基本类的名称作为一个元组跟在定义类时的类名称之后。

基本类的__init__方法专门使用self变量调用，这样我们就可以初始化对象的基本类部分。

记住：python不会自动调用基本类的constructor,需要亲自专门调用它。