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Python

Sebastiaan Stoffels
Sebastiaan Stoffels
3,075 Points
Posted by Sebastiaan Stoffels
Sebastiaan Stoffels
3,075 Points

Object Oriented Python - Inheritance Quiz

Hi there, Just making my way through the new Object Oriented Python course, and wanted to check my understanding on something. I'm on the section covering Inheritance, and on Quiz question 4 of 5 the following question is posed:

The following code:

class Orange(Fruit):
    has_pulp = True

    def squeeze(self):
        return has_pulp

Orange().squeeze() will return True

The answer is false, but I want to know why. The only thing I could find is that the function definition for squeeze() is missing the 'self' part, i.e. it should be:

def squeeze(self):
    return self.has_pulp

In which case, it would return True

Am I right that is the reason? Or is there another 'learning' from this particular question.

3 Answers

Christopher Shaw
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PLUS
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Christopher Shaw
Python Web Development Techdegree Graduate 58,236 Points
Christopher Shaw
.a{fill-rule:evenodd;}techdegree seal-36
Christopher Shaw
Python Web Development Techdegree Graduate 58,236 Points

Self refers to the current instance of the class. In your first code, the has_pulp without self is not the same vaiable as the class variable definded earlier. With self.has_pulp now refers to the class variable.

hamdi ismail
PLUS
hamdi ismail
Courses Plus Student 8,927 Points
hamdi ismail
hamdi ismail
Courses Plus Student 8,927 Points

no you are right if it was self.has_pulp then it will be true

Ikuyasu Usui
Ikuyasu Usui
35 Points
Ikuyasu Usui
Ikuyasu Usui
35 Points

It gives error right? Orange() is not a class, but an instance acutally: Orange is a class while Orange() is an instance. But the Orange class doesn't have self.has_pulp, so asking for it produces an error. I think Orange.squeeze() doesn't work either because you need to pass an instance of Orange. So Orange.squeeze(Orange()) works. Am I correct on all these?

Ikuyasu Usui
Ikuyasu Usui
35 Points

Orange.squeeze(Orange()) doesn't work. I guess making attribute like self.attribute is important.