Editing Double dispatch (section)

==== Output ====
The output example below shows the results of two SURFACE visitor objects being polymorphically passed over a list of polymorphic SHAPE objects. The visitor code pattern is only aware of SHAPE and SURFACE generically and not of the specific type of either. Instead, the code relies on run-time polymorphism and the mechanics of agents to achieve a highly flexible co-variant relationship between these two deferred classes and their descendants.

 draw a {{colors|white|red|red}} POLYGON on ETCHASKETCH
 draw a {{colors|white|red|red}} POLYGON on GRAFFITI_WALL
 draw a {{colors|white|grey|grey}} RECTANGLE on ETCHASKETCH
 draw a {{colors|white|grey|grey}} RECTANGLE on GRAFFITI_WALL
 draw a {{colors|white|green|green}} QUADRILATERAL on ETCHASKETCH
 draw a {{colors|white|green|green}} QUADRILATERAL on GRAFFITI_WALL
 draw a {{colors|white|blue|blue}} PARALLELOGRAM on ETCHASKETCH
 draw a {{colors|white|blue|blue}} PARALLELOGRAM on GRAFFITI_WALL
 draw a {{colors|black|yellow|yellow}} POLYGON on ETCHASKETCH
 draw a {{colors|black|yellow|yellow}} POLYGON on GRAFFITI_WALL
 draw a {{colors|white|purple|purple}} RECTANGLE on ETCHASKETCH
 draw a {{colors|white|purple|purple}} RECTANGLE on GRAFFITI_WALL