[Rd] group generics

[Ross Boylan]

Thanks for your help.  I had two concerns about using as: that it would
impose some overhead, and that it would require me to code an explicit
conversion function.  I see now that the latter is not true; I don't
know if the overhead makes much difference.

On Thu, 2009-12-03 at 13:00 -0800, Martin Morgan wrote:
> setMethod("Arith", signature(e1="numeric", e2="B"), function(e1, e2) {
>     new("B", xb=e1*e2 at xb, callGeneric(e1, as(e2, "A")))
> })

Things were getting too weird, so I punted and used explicitly named
function calls for the multiplication operation that was causing
trouble.

Ross