PolyD is a pure Java tool that, using dynamic bytecode generation, allows the user to define customized dispatching policies, altering many aspects of message dispatching that are usually predermined and that cannot be easily changed.
In simpler words, using PolyD you can define a set of methods and invoke them according to user-defined criteria. For example, PolyD can be used to implement a visitor-like mechanism, or general multiple dispatching, or more unusual dispatching policies. PolyD makes it possible to personalize many aspects of the dispatching process: the handling of null arguments, of missing methods, of ambiguities, of the method invocation, and so on. In that respect, PolyD is a more general and flexible solution to the "expression problem" than other tools.
PolyD is distributed under the terms of the GNU Lesser General Public License. The use of this library in proprietary programs is therefore allowed under the terms specified by that license.