1.在外面例項化被組合類

#選課系統（在外面例項化被組合類）
class School:
    def __init__(self,name,addr):
        self.name = name
        self.addr = addr

class Course:
    def __init__(self,name,price,period,school):
        self.name = name
        self.price = price
        self.period = period
        self.school = school

s1 
 
= School('oldboy','北京')
s2 = School('oldboy','南京')
s3 = School('oldboy','東京')
c1 = Course('linux',10,'1h',s1)
meg = '''
    1 : 北京
    2 : 南京
    3 : 東京
'''
while True:
    print(meg)
    menu = {
        '1':s1,
        '2':s2,
        '3':s3
    }
    choice = input('選擇學校>>:')
    school_obj 
 
= menu[choice]
    choice2 = input('課程>>:')
    new_course = Course('linux','10','1h',school_obj)
    print(new_course.school.name)

2.在類裡面例項化被組合的類

class School:
    def __init__(self,name,addr):
        self.name = name
        self.addr = addr

class Course:
    def __init__(self,name,price,period,school_name,addr):
        self.name 
 
= name
        self.price = price
        self.period = period
        self.school = School(school_name,addr)

c1 = Course('linux',10,'1h','oldboy','北京')
print(c1.school.name)