On April 13 2004, the patent "Extensible and efficient double dispatch in single-dispatch object-oriented programming languages" was issued to International Business Machines in the United States. The 'inventor' was John Vlissides.
The patent describes a method, which involves a specific application of the Visitor Pattern, of implementing Double Dispatch in a Single Dispatch Object Oriented Programming Language.
Somebody will patent *all* the GOF patterns, and then everyone will have to use procedural/relational instead. Bwaaa haa ha haa ha. -Tevilmind
Or better yet, will have to go functional with languages that support true multi-dispatch. Now where is Vlissides' god now? :-) --Samuel Falvo
Isn't this patent almost identical to the staggered Visitor approach described in Pattern Hatching (see Visitor In Frameworks for example)? If not, then what is the innovation? Surely John Vlissides isn't patenting something he's already published!
See Software Patents
This is what permitting patents on software leads to- patents on software.
See original on c2.com 