[Rd] Another problem with next method

From: Gabor Grothendieck <ggrothendieck_at_myway.com>
Date: Thu 28 Oct 2004 - 09:38:55 EST

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))

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Received on Thu Oct 28 09:46:22 2004

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