Why is it possible to use an object as a counter?

You are not using the object as a counter but the de-reference of the object. $self is the object but it's also a reference to a scalar (since that's how you have constructed it). When you de-reference the object therefore you get a scalar and so $$self++ is incrementing the scalar. Since the example you mentioned starts with $active = 0, that's the value from which you will be incrementing.

In reply to Re: Why does $$self++ work? by hippo
in thread Why does $$self++ works? by rob25

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