Python Setter method in class not giving expected output

Question

I'm trying to update the rank field in the node using setters in Python. Below is the code I've used:

class Tree(object):
    def __init__(self,u):
        self.parent=u
        self.rank=0

    def get_parent(self):
        return self.parent

    def get_rank(self):
        return self.rank

    def set_parent(self,v):
        self.parent=v

    def set_rank(self,v):
        self.rank=v

And then I'm running the following code:

Tree(0).get_rank()
Tree(0).set_rank(5)
Tree(0).get_rank()

Output:

Expected Output:

Here, the output I'm getting is 0 itself instead of 5 which I'm expecting. Can anybody let me know where exactly am I going wrong in the code or even conceptually?

Tree(0) on 2nd line is not same reference as Tree(0) on 1st line. Try doing id(Tree(0)) for both lines to see it. — shahkalpesh
– shahkalpesh, Commented Nov 11, 2019 at 7:44
You are performing your operations on a new object each time, so you're throwing away your intermediate state. Besides, getters and setters are very common in Java, but are very uncommon in Python. Just set and read the attributes directly — Energya
– Energya, Commented Nov 11, 2019 at 7:44

Thierry Lathuille · Accepted Answer · 2019-11-11 07:44:46Z

2

You are creating and using a new Tree object on each line:

Tree(0).get_rank()   # first tree object
Tree(0).set_rank(5)  # second tree object
Tree(0).get_rank()   # third tree object

So, when you call get_rank on the third one, it's freshly initialized, so its rank is 0.

answered Nov 11, 2019 at 7:44

Thierry Lathuille

24.4k10 gold badges49 silver badges57 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

gbruenjes · Accepted Answer · 2019-11-11 07:44:20Z

1

You have to create an object of your class:

tree = Tree(0)
tree.get_rank()
tree.set_rank(5)
tree.get_rank()

answered Nov 11, 2019 at 7:44

gbruenjes

4,2251 gold badge18 silver badges32 bronze badges

Collectives™ on Stack Overflow

Python Setter method in class not giving expected output

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related