From: "A.J. Rossini" <[EMAIL PROTECTED]>
You are mixing S3 and S4 paradigms. You want setMethod to define the method, not the FunctionName.ClassOfObject S3 specification.
That just proves my newbie-ness in R programming. I would appreciate it if you could provide me the S4 equivalent. According to the documentation in the methods package:
"Computations using the notion of 'NULL' class attributes or of class attributes with multiple class names are not really compatible with the ideas in the 'methods' package."
So I guess a different approach should be taken in S4?
On 4/22/05, Ali - <[EMAIL PROTECTED]> wrote:
>
> >
> >
> >f <- function(...) UseMethod("f", NULL)
> >
> >f.NULL <- function(...) {
> > args <- list(...)
> > classes <- sapply(args, class)
> > .Class <- paste(classes, collapse = ".")
> > NextMethod("f", ...)
> >}
> >
> >f.numeric <- function(...) 2 * ..1
> >f.numeric.numeric <- function(...) ..1 + ..2
> >f.character.numeric.Date <- function(...) {
> > args <- list(...)
> > paste(args[[1]], args[[2]], format(args[[3]], "%Y-%m-%d"))
> >}
> >f.default <- function(...) print(list(...))
> >
> >
> >f(1) # 2
> >f(1,2) # 3
> >f("a", 23, Sys.Date()) # "a 23 2005-04-21"
> >f() # list()
>
> Thanks Gabor! This answers a big part of my question. I am just curious why
> something like this doesn't work in S4:
>
> -------------------------
> setGeneric("foo", function(object, ...) standardGeneric("foo"))
>
> foo.NULL <- function(object, ...) {
> args <- list(...)
> classes <- sapply(args, class)
> .Class <- paste(classes, collapse = ".")
> }
>
> foo.default <- function(object, ...) paste("wrong args!")
>
> foo.numeric <- function(object, ...) 2 * ..1
> foo.numeric.numeric <- function(object, ...) ..1 + ..2
>
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>
-- best, -tony
"Commit early,commit often, and commit in a repository from which we can easily
roll-back your mistakes" (AJR, 4Jan05).
A.J. Rossini [EMAIL PROTECTED]
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