Name:
  Object Pool

Intent:
  reuse (as opposed to recycle) objects that would be garbage collected

Structure:
  - Pool has a store for reusable objects
  - Pool has two methods get and return with the obvious meaning
  - Pool needs cooperating clients
  - Reusable class is private inner and possibly static subclass of Pool
    (to insure constructor is unaccessible to clients)
    the needs interface

Notes:
  - clean references to other object in reusable when it goes into the pool
  - reset references of object returned to the pool
  - initialize reusable object when given to client
  - pool should be a singleton
  - for each type of reusable there is different pool
  - store is very simple for linked reusable