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Note on improving the reflective copy object architecture.

Basic abstractions:

/** Creates an instance of an ObjectCopier to be used for a single session.
 */
ObjectCopierFactory {
    ObjectCopier make() ;
}

/** Used to copy objects in a single session: multiple calls to the
 * same ObjectCopier instance will share all aliases.
ObjectCopier {
    Object copy( Object obj ) throws ReflectiveCopyException ;
}

------------------------
Reflective case:

/** Used to copy an Object of a particular type.  Preserves aliasing through
 * oldToNew.
 */
interface ClassCopier {
    Object copy( IdentityHashMap oldToNew, Object source ) throws ReflectiveCopyException ;
}

/** Create a ClassCopier for a particular type.
 */
ClassCopierFactory {
    ClassCopier get( Class cls ) throws ReflectiveCopyException ;
}

Use filter pattern: use a chain of ClassCopierFactory instances, take first non-null result.

Special ClassCopier instances:
    DefaultClassCopiers
	ClassCopier makeMapCopier( ClassCopierFactory ccf ) 
	ClassCopier getIdentityCopier() 
	ClassCopier getErrorCopier()

ClassCopierFactory instances:

    - A client may create a special ClassCopierFactory with arbitrary behavior.
    - An ArrayClassCopierFactory that returns a ClassCopier for an array, and 
      null for non-array
    - A OrdinaryClassCopierFactory that returns a ClassCopier for any Class,
      and throws ReflectiveCopyException if it cannot create a ClassCopier.
    - An ImmutableClassCopierFactory that returns an IdentityClassCopier if
      the class is immutable (also has registration API).
    - A CachingClassCopierFactory that maintains a cache of know ClassCopier
      instances for particular classes (also has a registration API).
    - PipelineCopierFactory:
	- Does Caching -> Special (may be no-op) -> Array -> Ordinary
	- Updates cache if needed
	- Provides API for:
	    - registration of know ClassCopier instances
	    - registration of immutable classes (go straight to cache)
	    - registration of optional special ClassCopierFactory
	- passes itself to Array and Ordinary ClassCopierFactory instances

    DefaultClassCopierFactories:
	ClassCopierFactory makeCachingClassCopierFactory()
	ClassCopierFactory makeArrayClassCopierFactory( ClassCopierFactory ) 
	ClassCopierFactory makeOrdinaryClassCopierFactory( ClassCopierFactory ) 
