Yes, the "boolean test" method is more simple and maintainable. As a performance it is equal or better to the approach with wrappers/AUTOLOAD because you always must check some condition in the wrapper.

I see that if we have symtables per instance this will hurt the performance of all objects and the gain in flexibility is minimal. The suggested re-blessing method seems more general and could do the same without penalty for other objects.

Thanks
luben