Bounded Priority Queue Inheritance vs Composition

Question

I want to write a Bounded Priority Queue class. This is essentially a priority queue but has a bound on the number of elements that can be there in the queue. So, if I insert a new element and the queue is full, then I see if the element is greater than the top of the queue. If yes, then I discard the new element. If no, then I remove the top element and insert this new element (and the queue gets automatically reorganized). I have currently implemented BoundedPriorityQueue as derived from PriorityQueue having a "maxCount" member and I have overridden the add method and added the functionality I described above. I am wondering if I should consider doing it the composition way rather than the inheritance way. My current approach seems simple though.

If I were to go for composition, then I have to derive from the AbstractQueue class, implement the methods and then compose the priority queue with it.

Thanks,

Venk

Answer 1

in my opinion it is better to use composition. because, inheritance this way is the violation of Liskov substitution principle. derived types shouldn't replace base types' functionality. this link will be useful: prefer composition over inheritance