flyweight. Why do we need UnsharedConcreteFlyweight and ConcreteFlyweight?

Question

OOP

I can't figure out why UnsharedConcreteFlyweight is needed in the Flyweight pattern? Many implement this pattern without this component. How to be with him and what does he do?

Answer 1

Imagine that each flyweight instance should have a reference to an immutable 10k x 10k matrix. Since the pattern saves memory, it would be logical to keep the matrix in a single copy, despite the presence of a pool of opportunists. In ConcreteFlyweight this matrix is ​​stored. On the other hand, why do we need a pool of objects if they generally have all the same properties? UnsharedConcreteFlyweight is used to store differences.