属性创建和引用Python类多级继承时出错

我有下面的程序，试图演示多级继承。不幸的是，在调用

m2

和

有资格获得奖励

方法时，我得到以下信息：

m2=Marks()
m2.eligible_for_reward()

错误：

Marks has no attribute totalmarks

代码如下：

# Define a class as 'student'
class Student:
    # Method
    def getStudent(self):
        self.name = input("Name: ")
        self.age = input("Age: ")
        self.gender = input("Gender: ")

#The Test Class inherits from the Student Class.
class Test(Student):
    # Method
    def getMarks(self):
        self.stuClass = input("YearGroup/Class: ")
        print("Enter the marks of the respective subjects")
        self.literature = int(input("Literature: "))
        self.math = int(input("Math: "))
        self.biology = int(input("Biology: "))
        self.physics = int(input("Physics: "))

# Note that the Marks Class inherits from the Test Class and in doing so inherits from the Student Class
class Marks(Test):    
    # Method
    def display(self):
        print("\n\nName: ",self.name)
        print("Age: ",self.age)
        print("Gender: ",self.gender)
        print("Class Year Group: ",self.stuClass)
        self.totalmarks=self.literature+self.math+self.biology+self.physics
        print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
        if self.totalmarks>=90 and self.age>13:
            print("You are eligible for the fabulous school sponsored trip to London")
        else:
            print("Sorry, you are not eligible and so are going nowhere....!")

更新：

我还尝试了以下方法，即在相关方法中定义self.totalmarks，但也出现了一个错误：未定义名称“totalmarks”

def eligible_for_reward(self):
        self.totalmarks=totalmarks
        if self.totalmarks>=90 and self.age>13:
            print("You are eligible for the fabulous school sponsored trip to London")
        else:
            print("Sorry, you are not eligible and so are going nowhere....!")

此外，我也试过了

    m2=Marks()
    m2.display()
    m2.eligible_for_reward()

和错误：

AttributeError: 'Marks' object has no attribute 'name'

---

您可以在

display（）

方法的

Marks

类中定义属性

self.totalmarks

因此，当您为奖励（）调用合格的奖励时，此时未定义totalmarks。因此，您可以先调用display（）方法来解决此问题：

m2=Marks()
m2.dispay()
m2.eligible_for_reward()

但这行不通，因为

self.literature

self.math

self.biology

self.physics

目前也没有定义

您必须向所有类添加init（）方法，以便在内部调用super（），并正确实例化该类，如下所示：

class Student:
    def __init__(self):
        self.name = input("Name: ")
        self.age = input("Age: ")
        self.gender = input("Gender: ")

class Test(Student):
    def __init__(self):
        super(Test, self).__init__()
        self.stuClass = input("YearGroup/Class: ")
        print("Enter the marks of the respective subjects")
        self.literature = int(input("Literature: "))
        self.math = int(input("Math: "))
        self.biology = int(input("Biology: "))
        self.physics = int(input("Physics: "))

class Marks(Test):    
    def __init__(self):
        super(Marks, self).__init__()
        self.total_marks = self.literature + self.math + self.biology + self.physics

    def display(self):
        print("\n\nName: ",self.name)
        print("Age: ",self.age)
        print("Gender: ",self.gender)
        print("Class Year Group: ",self.stuClass)

        print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
        if self.total_marks>=90 and self.age>13:
            print("You are eligible for the fabulous school sponsored trip to London")
        else:
            print("Sorry, you are not eligible and so are going nowhere....!")

class Student:
    # Method
    def __init__(self):
        self.name = input("Name: ")
        self.age = int(input("Age: "))
        self.gender = input("Gender: ")

    def setMarks(self):
         self.stuClass = input("YearGroup/Class: ")
         print("Enter the marks of the respective subjects")
         self.literature = int(input("Literature: "))
         self.math = int(input("Math: "))
         self.biology = int(input("Biology: "))
         self.physics = int(input("Physics: "))
         self.totalmarks=self.literature+self.math+self.biology+self.physics

    def display(self):
         print("\n\nName: ",self.name)
         print("Age: ",self.age)
         print("Gender: ",self.gender)
         print("Class Year Group: ",self.stuClass)
         self.totalmarks=self.literature+self.math+self.biology+self.physics
         print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
         if self.totalmarks>=90 and self.age>13:
             print("You are eligible for the fabulous school sponsored trip to London")
         else:
             print("Sorry, you are not eligible and so are going nowhere....!")

您可以按如下方式使用它：

marks = Marks()
marks.eligible_for_reward()
marks.display()

---

正如我在评论中提到的那样，我不认为您子类化的方式有什么原因。所以我把它放在一个班级里，就像这样：

class Student:
    def __init__(self):
        self.name = input("Name: ")
        self.age = input("Age: ")
        self.gender = input("Gender: ")

class Test(Student):
    def __init__(self):
        super(Test, self).__init__()
        self.stuClass = input("YearGroup/Class: ")
        print("Enter the marks of the respective subjects")
        self.literature = int(input("Literature: "))
        self.math = int(input("Math: "))
        self.biology = int(input("Biology: "))
        self.physics = int(input("Physics: "))

class Marks(Test):    
    def __init__(self):
        super(Marks, self).__init__()
        self.total_marks = self.literature + self.math + self.biology + self.physics

    def display(self):
        print("\n\nName: ",self.name)
        print("Age: ",self.age)
        print("Gender: ",self.gender)
        print("Class Year Group: ",self.stuClass)

        print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
        if self.total_marks>=90 and self.age>13:
            print("You are eligible for the fabulous school sponsored trip to London")
        else:
            print("Sorry, you are not eligible and so are going nowhere....!")

class Student:
    # Method
    def __init__(self):
        self.name = input("Name: ")
        self.age = int(input("Age: "))
        self.gender = input("Gender: ")

    def setMarks(self):
         self.stuClass = input("YearGroup/Class: ")
         print("Enter the marks of the respective subjects")
         self.literature = int(input("Literature: "))
         self.math = int(input("Math: "))
         self.biology = int(input("Biology: "))
         self.physics = int(input("Physics: "))
         self.totalmarks=self.literature+self.math+self.biology+self.physics

    def display(self):
         print("\n\nName: ",self.name)
         print("Age: ",self.age)
         print("Gender: ",self.gender)
         print("Class Year Group: ",self.stuClass)
         self.totalmarks=self.literature+self.math+self.biology+self.physics
         print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
         if self.totalmarks>=90 and self.age>13:
             print("You are eligible for the fabulous school sponsored trip to London")
         else:
             print("Sorry, you are not eligible and so are going nowhere....!")

用法示例：

s1 = Student()
>>> Name: Hans
>>> Age: 17
>>> Gender: m
s1.setMarks()
>>> YearGroup/Class: 2017
>>> Enter the marks of the respective subjects
>>> Literature: 11
>>> Math: 14
>>> Biology: 42
>>> Physics: 10

s1.display()


>>> Name:  Hans
>>> Age:  17
>>> Gender:  m
>>> Class Year Group:  2017
>>> Total Marks:  77

s1.eligible_for_reward()
>>> Sorry, you are not eligible and so are going nowhere....!

---

以下是经过最少编辑的工作代码，希望对您有所帮助：-

class Student:
    # Method
    def getStudent(self):
        self.name = input("Name: ")
        self.age = int(input("Age: "))
        self.gender = input("Gender: ")

#The Test Class inherits from the Student Class.
class Test(Student):
    def __init__(self):
        super().__init__()
        super().getStudent()
    # Method
    def getMarks(self):
        self.stuClass = input("YearGroup/Class: ")
        print("Enter the marks of the respective subjects")
        self.literature = int(input("Literature: "))
        self.math = int(input("Math: "))
        self.biology = int(input("Biology: "))
        self.physics = int(input("Physics: "))

# Note that the Marks Class inherits from the Test Class and in doing so inherits from the Student Class
class Marks(Test):
    def __init__(self):
        super().__init__()
        super().getMarks()
    # Method
    def display(self):
        print("\n\nName: ",self.name)
        print("Age: ",self.age)
        print("Gender: ",self.gender)
        print("Class Year Group: ",self.stuClass)
        self.totalmarks=self.literature+self.math+self.biology+self.physics
        print("Total Marks: ", self.literature + self.math + self.biology + self.physics)

    def eligible_for_reward(self):
        if self.totalmarks>=90 and self.age>13:
            print("You are eligible for the fabulous school sponsored trip to London")
        else:
            print("Sorry, you are not eligible and so are going nowhere....!")



mrk = Marks()
mrk.display()
mrk.eligible_for_reward()

---

只有在调用

Marks.display（）

时，才能设置

totalmarks

。您没有调用

Marks.display（）

，因此该属性不存在。非常感谢。根据下面的建议答案，我尝试了这个方法，但出现了一个错误。请查看

display（）

需要哪些属性，以及这些属性的设置位置。我可以看到它们是由用户在上一个类中输入的，但不确定如何在新的类/方法中再次声明它们。这就是我需要的帮助和指导！在Marks类中，我可以简单地初始化init中的属性吗？例如self.literature=等。这些属性完全不相关，但是您的继承树（从设计角度来看）完全错误。继承在语义上是一种“is a”关系（如果B从a继承，那么B就是a）。很明显，分数不是考试，学生也不是。。。这里要描述的关系是“has a”（或“has many”）关系，它们是通过聚合实现的。理想情况下，我希望正确定义它，这样就不必首先调用display方法。这是如何做到的？请参阅我的编辑。另外，使用您的解决方案，我现在得到了以下错误：AttributeError:“Marks”对象没有属性“name”。解决方案需要解释如何最好地实现这一点，这样它才能工作！请注意，

display（）

使用其他方法设置的属性。你不能只告诉他们运行

display（）

。谢谢你，阿列克谢-我马上就去试试。你能补充一下你的答案吗，“超级”部分到底做了什么。我不认为在创建类时需要显式地使用“super”来扩展/继承超类……我不清楚这一点。我会将

input（）

调用移出类。您希望能够从不同的源创建这样一个类，而不仅仅是用户输入。我正在进行子分类以演示多级继承。关于如何用你的答案证明这一点的任何建议。这是我这项任务的重点。很多人都感谢他们尝试将学生分类为本科生、毕业生等。正如布鲁诺·德舒利尔（bruno desthuilliers）在评论中所说的那样，这种关系应该是“a”。所以本科生是学生。它继承了诸如姓名、年龄等标准属性。但是可以有额外的字段和函数，只有本科生才有。因此，所有类继承的关系都必须是is-a，这是一条严格的规则。（例如，如果B继承自A，则B为A）。。。？我从来不知道这件事。在游戏中，玩家不是从分数或世界级继承的吗？我想澄清一下这一点是的，这实际上就是继承的概念。不，我不这么认为，玩家可能有一个Score属性，它本身可以是一个类，但是Score不会从玩家继承。但是继承是关于继承属性和方法，不是吗？e、 玩家可以继承分数的属性，比如当前的分数或健康状况。如果某个属性是另一个类的属性，则该属性不具有score属性，这也是继承的一个示例。这就是一些教程似乎教它的方式。只是添加了超级类的init函数，并触发了一些其他必要的函数。将年龄转换为int并调用display函数初始化totalmarks变量。