R devel - Dec 2006 - Wondering about methods (selecting a less specialized method)

Hi All,

I find myself wondering if there is a canonical means of achieving the
multiple-dispatch version of 'super'? Specifically, I have a set of
classes

A, B, X and Y where B extends A

and a method Foo with the signature (X,A,Y) and I'd like to implement
Foo with the signature (X,B,Y) such that it calls Foo_(X,A,Y) and then
does "other stuff." This gets a bit complicated with multiple
inheritance but at the moment the best I can think to do is an
explicit call to selectMethod.

"Byron Ellis" <ellis at stat.harvard.edu> writes:
> Hi All,
>
> I find myself wondering if there is a canonical means of achieving the
> multiple-dispatch version of 'super'? Specifically, I have a set of
> classes
>
> A, B, X and Y where B extends A
>
> and a method Foo with the signature (X,A,Y) and I'd like to implement
> Foo with the signature (X,B,Y) such that it calls Foo_(X,A,Y) and then
> does "other stuff." This gets a bit complicated with multiple
> inheritance but at the moment the best I can think to do is an
> explicit call to selectMethod.
I would expect callNextMethod to work in most cases.  Have you tried
that?

setMethod("Foo", c("X", "B", "Y"),
          function(x, b, y) {
              ans <- callNextMethod()
              ## more
          })

+ seth