Base class for pool 'foreach' iterators. The constructor receives a
slice of the items to be iterated over.
Note that the iterators pass the pool items as type T to the foreach
delegate, not as type ItemType. This is because, when ref iterating over
a pool of structs, we want the references to be to the structs in the
pool themselves, not the pointer to the structs in the pool.
Base class for pool 'foreach' iterators. The constructor receives a slice of the items to be iterated over.
Note that the iterators pass the pool items as type T to the foreach delegate, not as type ItemType. This is because, when ref iterating over a pool of structs, we want the references to be to the structs in the pool themselves, not the pointer to the structs in the pool.