類的派生

目錄

• 1、派生
  • 1.1 派生方法一(類調用)
  • 1.2 派生方法二(super)

1、派生

• 派生：子類中新定義的屬性的這個過程叫作派生，而且須要記住子類在使用派生的屬性時始終以本身的爲準

1.1 派生方法一(類調用)

• 指名道姓訪問某一個類的函數：該方式與繼承無關

class OldboyPeople:
    """因爲學生和老師都是人，所以人都有姓名、年齡、性別"""
    school = 'oldboy'

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


class OldboyStudent(OldboyPeople):
    """因爲學生類沒有獨自的__init__()方法，所以不須要聲明繼承父類的__init__()方法，會自動繼承"""

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


class OldboyTeacher(OldboyPeople):
    """因爲老師類有獨自的__init__()方法，所以須要聲明繼承父類的__init__()"""

    def __init__(self, name, age, gender, level):
        OldboyPeople.__init__(self, name, age, gender)
        self.level = level  # 派生

    def score(self, stu_obj, num):
        print('%s is scoring' % self.name)
        stu_obj.score = num


stu1 = OldboyStudent('tank', 18, 'male')
tea1 = OldboyTeacher('nick', 18, 'male', 10)

print(stu1.__dict__)

{'name': 'tank', 'age': 18, 'gender': 'male'}

print(tea1.__dict__)

{'name': 'nick', 'age': 18, 'gender': 'male', 'level': 10}

1.2 派生方法二(super)

• 嚴格以來繼承屬性查找關係

• super()會獲得一個特殊的對象，該對象就是專門用來訪問父類中的屬性的（按照繼承的關係）

• super().__init__(不用爲self傳值)

• super的完整用法是super(本身的類名,self),在python2中須要寫完整，而python3中能夠簡寫爲super()

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, stu_id):
        # OldboyPeople.__init__(self,name,age,sex)
        # super(OldboyStudent, self).__init__(name, age, sex)
        super().__init__(name, age, sex)
        self.stu_id = stu_id

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


stu1 = OldboyStudent('tank', 19, 'male', 1)

print(stu1.__dict__)

{'name': 'tank', 'age': 19, 'sex': 'male', 'stu_id': 1}