[christophilus]

Except, this is not premature optimization. Chess programs are a domain the author is familiar with. He goes out of his way to explain why-- based on his experience-- chess code should be written with space-optimization in mind.

Secondly, if you want to support non-standard boards, his solution requires a small tweak (depending on the language): long -> bigint and some parameter to denote board size.

[valuearb]

Yea, you are describing code that’s more difficult to enhance and maintain.

Your pieces and board objects can have serialize/deserialize methods that write/read them to/from bitboards for most efficient storage for whatever variant of chess you want, while still having your code in an OO design that’s easier to understand and extend. And allow you to demonstrate the skills the gdmn interviewer wanted you to demonstrate, which is the actual point of the excercise!

[loup-vaillant]

I'd rather fail the interview than work for the one who failed me in this case.

Assuming I am asked to design something in a domain I am familiar with, where an OOP-looking solution is not a good approach, I will simply go with a good approach instead. If this triggers a discussion, wonderful. If the interviewer assumes I don't understand OOP, shame on them for not explicitly asking for an OOP design in the first place. And if the interviewer suggests I should go for an OOP design instead of my solution, I will contradict them on the spot —politely. I may comply for the sake of the exercise, but will repeat and insist that there are better approaches to this class of problems —politely.

More generally, I am highly sceptical of claims that OO designs are in general easier to understand, maintain, and extend (this includes this chess example, where I believe the bit-board approach is competitive even for variable board sizes). They're often not, if only because being OO for the sake of it tends to generate more code. More code to understand, more code to debug, more code to extend… you get the idea.

I also tend to believe OOP is not the best approach for most problem domains, possibly even including GUI (I have yet to study this in detail). I'd rather not work for shops that insist on using OOP everywhere.