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

    class Foo:
        pass

    class Bar:
        pass

    obj=Foo()
    obj.attr=Bar()

    obj.xxx
    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

 class Foo1:
        pass
    class Foo2:
        pass
    class Foo3:
        pass

    class Bar:
        pass

    obj_from_bar=Bar()

    obj1=Foo1()
    obj2=Foo2()
    obj3=Foo3()

    obj1.attr1=obj_from_bar
    obj2.attr2=obj_from_bar
    obj3.attr3=obj_from_bar

3.怎么使用组合

class OldboyPeople:
    school = 'Oldboy'

    def __init__(self,name,age,sex,):
        self.name = name
        self.age = age
        self.sex = sex

class OldboyStudent(OldboyPeople):
    def __init__(self, name, age, sex,score=0):
        OldboyPeople.__init__(self,name,age,sex)
        self.score = score
        self.courses=[]

    def choose_course(self):
        print('%s choosing course' % self.name)

    def tell_all_course(self):
        print(('学生[%s]选修的课程如下' %self.name).center(50,'='))
        for obj in self.courses:
            obj.tell_info()
        print('='*60)

class OldboyTeacher(OldboyPeople):
    def __init__(self,name,age,sex,level):
        OldboyPeople.__init__(self,name,age,sex)
        self.level=level
        self.courses=[]

    def score(self,stu,num):
        stu.score=num

    def tell_all_course(self):
        print(('老师[%s]教授的课程如下' %self.name).center(50,'*'))
        for obj in self.courses:
            obj.tell_info()
        print('*'*70)

class Course:
    def __init__(self,c_name,c_price,c_period):
        self.c_name = c_name
        self.c_price = c_price
        self.c_period = c_period

    def tell_info(self):
        print('<课程名:%s 价钱:%s 周期:%s>' %(self.c_name,self.c_price,self.c_period))

# 创建课程对象
python=Course('python全栈开发',1900,'5mons')
linux=Course('linux架构师',900,'3mons')


stu1=OldboyStudent('刘二蛋',38,'male')
stu1.courses.append(python)
stu1.courses.append(linux)
# print(stu1.courses)
stu1.tell_all_course()


tea1=OldboyTeacher('egon',18,'male',10)
tea1.courses.append(python)
# print(tea1.courses)
tea1.tell_all_course()