Complex sentence: However, clients which receive a used object must receive an object which is an initialized state, they should presume that the object is ready to be used after the constructor runs or the object is returned from a class factory which manages the pool.
Split into simpler sentences: However, clients which receive a used object must receive an object which is in an initialized state. That is, they should presume that the object is ready to be used after the constructor runs or the object is returned from a class factory which manages the pool.