From ggrothendieck at myway.com  Thu Oct 28 01:38:55 2004
From: ggrothendieck at myway.com (Gabor Grothendieck)
Date: Thu Oct 28 01:39:02 2004
Subject: [Rd] Another problem with next method
Message-ID: <loom.20041028T013716-745@post.gmane.org>


I have another problem with NextMethod.  Not sure if its related
to the last problem.

In this example, we have a generic called ff with methods
for AsIs and test classes.  We call the generic with an
object of AsIs class.  The corresponding method adds 1 to it
and then changes the class to test followed by issuing a
NextMethod.  However, that results in this error (using R
2.0.0, 2004-10-04 Windows XP):

	Error in NextMethod("ff") : No method to invoke

Why can't NextMethod find ff.test ?

I also tried a number of variations of this including adding x = x
to the NExtMethod argument list but none of these variations worked.

---

ff <- function(x, ...) UseMethod("ff")
ff.AsIs <- function(x, ...) {
	x <- x + 1
	class(x) <- "test"
	NextMethod("ff")
}
ff.test <- function(x, ...) cat(x, class(x), ..., "\n")
ff(I(3))


[Rd] Another problem with next method
Gabor Grothendieck