During instantiation of a class how to check if an object of that class already exists and if it does, point to the already existing object?

Question

I was asked this question in an interview. What I tried to do was as follows:

class A:
    l = []
    def __init__(self):
        if len(A.l)==0:
            A.l.append(self)
        else:
            return A.l[0]

a = A()
b = A()

I came home and ran this code and understood that it won't work.

So I would like to know what is the correct way to solve this problem. The expected result is that when A() is called for the second time, b should point to the object that is already stored in a (the first created object).

sad to know :( Anyway there are lot of fish (I mean jobs) in the market. — hspandher, Oct 24 '18 at 13:05

score 1 · Accepted Answer · answered Oct 24 '18 at 13:02

1

You want to implement something like Singleton. Most easier approach would be to overwrite __new__ instead of __init__.

answered Oct 24 '18 at 13:02

hspandher

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During instantiation of a class how to check if an object of that class already exists and if it does, point to the already existing object?

1 Answers1