Class 继承于 python

Question

我正在解决这个问题：

Consider the following hierarchy of classes:

class Person(object):     
    def __init__(self, name):         
        self.name = name     
    def say(self, stuff):         
        return self.name + ' says: ' + stuff     
    def __str__(self):         
        return self.name  

class Lecturer(Person):     
    def lecture(self, stuff):         
        return 'I believe that ' + Person.say(self, stuff)  

class Professor(Lecturer): 
    def say(self, stuff): 
        return self.name + ' says: ' + self.lecture(stuff)

class ArrogantProfessor(Professor): 
    def say(self, stuff): 
        return 'It is obvious that ' + self.say(stuff)

As written, this code leads to an infinite loop when using the Arrogant Professor class.

Change the definition of ArrogantProfessor so that the following behavior is achieved:

e = Person('eric') 
le = Lecturer('eric') 
pe = Professor('eric') 
ae = ArrogantProfessor('eric')

e.say('the sky is blue')              #returns   eric says: the sky is blue

le.say('the sky is blue')             #returns   eric says: the sky is blue

le.lecture('the sky is blue')         #returns   believe that eric says: the sky is blue

pe.say('the sky is blue')             #returns   eric says: I believe that eric says: the sky is blue

pe.lecture('the sky is blue')     #returns   believe that eric says: the sky is blue

ae.say('the sky is blue')         #returns   eric says: It is obvious that eric says: the sky is blue

ae.lecture('the sky is blue')     #returns   It is obvious that eric says: the sky is blue

我的解决方案是：

class ArrogantProfessor(Person):
    def say(self, stuff):
        return Person.say(self, ' It is obvious that ') +  Person.say(self,stuff)
    def lecture(self, stuff):
        return 'It is obvious that  ' + Person.say(self, stuff)

但是检查员只给这个答案打了半分。我犯了什么错误，这段代码失败的测试用例是什么？（我是 python 的新手，前段时间了解了类。）

Answer 1

您可能应该使用 super() 而不是硬连接 class Person:

class ArrogantProfessor(Person):
    def say(self, stuff):
        return super(ArrogantProfessor, self).say(self.lecture(stuff))
    def lecture(self, stuff):
        return 'It is obvious that ' + super(ArrogantProfessor, self).say(stuff)

Answer 2

作为编码硬件的前评分员，我认为，您应该已经产生了所需的输出，而不是使 ArrogantProfessor 仅仅是 Person。毕竟class这个名字表示还是应该subclassProfessor.

Answer 3

他可能想让你真正得到父 class。方法很简单。

Python2/3:

class ArrogantProfessor(Professor):
    def say(self, stuff):
        return 'It is obvious that ' + super(ArrogantProfessor, self).say(stuff)

Python 3只:

class ArrogantProfessor(Professor):
    def say(self, stuff):
        return 'It is obvious that ' + super().say(stuff)

无论哪种情况，ae.say("something") 应该 return:

"It is obvious that eric says: I believe that eric says: something"

这是因为父 class 是 Professor，而不是 Person。

同样，在你的演讲中class，你应该这样做：

def lecture(self, stuff):
    return 'I believe that ' + super(Lecturer, self).say(self, stuff) # or the Python3 version if you're using that

不过，您还不太清楚您想要什么。

Answer 4

给出的是：

class ArrogantProfessor(Professor):

但你这样做了：

class ArrogantProfessor(Person):

这导致成绩减半。

Answer 5

这应该是：

class ArrogantProfessor( Professor ):
    def lecture(self, stuff):
        return 'It is obvious that ' +  Person.say(self,stuff)

你不必在ArrogantProfessor中定义say()，因为它已经在Professor中定义了，它将使用lecture()中定义的方法child class.

Answer 6

在不知道他们想教你什么的情况下很难说。一个可能的猜测是，你正在学习继承，如果他们已经讲过 super，他们很可能希望你利用它来让 ArrogantProfessor 的输出看起来像：

eric says: It is obvious that STUFF

其中 STUFF 是您要传入的字符串。

Answer 7

     class Professor(Lecturer): 
        def say(self, stuff): 
            return "Prof. " + self.name + ' says: ' + self.lecture(stuff)

     class ArrogantProfessor( Professor ):
        def lecture(self, stuff):         
            return 'It is obvious that I believe that ' + Person.say(self, stuff)

Answer 8

对于第二部分，正确答案是：

class ArrogantProfessor(Professor):
    def lecture(self, stuff):
        return 'It is obvious that ' +  Lecturer.lecture(self,stuff)

Answer 9

第一部分的代码是：

class ArrogantProfessor( Professor ):
def lecture(self, stuff):
    return 'It is obvious that ' +  Person.say(self,stuff)

第二部分的代码是：

class ArrogantProfessor(Professor):
def lecture(self, stuff):
    return 'It is obvious that I believe that ' +  Person.say(self,stuff)

第三部分的代码是：

class Professor(Lecturer):
 def say(self, stuff): 
     return 'Prof. ' + self.name + ' says: ' + self.lecture(stuff)

希望有用

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