面向对象——组合

1.什么是组合？

组合指的是某一个对象拥有一个属性，该属性是另一个类的对象

  1     class Foo:
  2         pass
  3 
  4     class Bar:
  5         pass
  6 
  7     obj=Foo()
  8     obj.attr=Bar()
  9 
 10     obj.xxx
 11     obj.attr.yyy

2.为什么要使用组合？

通过为某一个对象添加属性(属性的值是另外一个类的对象)的方式,可以间接地将两个类关联/整合/组合到一起
从而减少类与类之间代码冗余

  1  class Foo1:
  2         pass
  3     class Foo2:
  4         pass
  5     class Foo3:
  6         pass
  7 
  8     class Bar:
  9         pass
 10 
 11     obj_from_bar=Bar()
 12 
 13     obj1=Foo1()
 14     obj2=Foo2()
 15     obj3=Foo3()
 16 
 17     obj1.attr1=obj_from_bar
 18     obj2.attr2=obj_from_bar
 19     obj3.attr3=obj_from_bar

3.怎么使用组合

  1 class OldboyPeople:
  2     school = 'Oldboy'
  3 
  4     def __init__(self,name,age,sex,):
  5         self.name = name
  6         self.age = age
  7         self.sex = sex
  8 
  9 class OldboyStudent(OldboyPeople):
 10     def __init__(self, name, age, sex,score=0):
 11         OldboyPeople.__init__(self,name,age,sex)
 12         self.score = score
 13         self.courses=[]
 14 
 15     def choose_course(self):
 16         print('%s choosing course' % self.name)
 17 
 18     def tell_all_course(self):
 19         print(('学生[%s]选修的课程如下' %self.name).center(50,'='))
 20         for obj in self.courses:
 21             obj.tell_info()
 22         print('='*60)
 23 
 24 class OldboyTeacher(OldboyPeople):
 25     def __init__(self,name,age,sex,level):
 26         OldboyPeople.__init__(self,name,age,sex)
 27         self.level=level
 28         self.courses=[]
 29 
 30     def score(self,stu,num):
 31         stu.score=num
 32 
 33     def tell_all_course(self):
 34         print(('老师[%s]教授的课程如下' %self.name).center(50,'*'))
 35         for obj in self.courses:
 36             obj.tell_info()
 37         print('*'*70)
 38 
 39 class Course:
 40     def __init__(self,c_name,c_price,c_period):
 41         self.c_name = c_name
 42         self.c_price = c_price
 43         self.c_period = c_period
 44 
 45     def tell_info(self):
 46         print('<课程名:%s 价钱:%s 周期:%s>' %(self.c_name,self.c_price,self.c_period))
 47 
 48 # 创建课程对象
 49 python=Course('python全栈开发',1900,'5mons')
 50 linux=Course('linux架构师',900,'3mons')
 51 
 52 
 53 stu1=OldboyStudent('刘二蛋',38,'male')
 54 stu1.courses.append(python)
 55 stu1.courses.append(linux)
 56 # print(stu1.courses)
 57 stu1.tell_all_course()
 58 
 59 
 60 tea1=OldboyTeacher('egon',18,'male',10)
 61 tea1.courses.append(python)
 62 # print(tea1.courses)
 63 tea1.tell_all_course()

View Code