[mabbo]

Abstraction, to me, is not about reducing lines of code but reducing cognitive load by hiding complexity. I don't need to know what kind of list, or how the list is implemented, I just need to know it's a list of some sort and has the usual list interface.

For example, I recently needed to randomly reorder a collection of objects, weighting some of them more heavily than others such that 'heavier' objects are more likely to come first. My first implementation was a mess, and was hard to test. So I created an abstract data structure that allowed inserts with weights and polls for a random value, applying the weighting. My business logic could use that abstract thing presuming it worked. The tricky part was hidden, and the code was cleaner.

In the case of the article, the abstraction the interviewer wants doesn't actually make the code clearer. It's just looking for checking off check boxes that the candidate wrote the word 'class' and jumped through the hoops the way the interviewer expected.