[R-pkg-devel] S3 is.unsorted registration

[Hugh Parsonage]

I would like to register an S3 method for `is.unsorted` for my
package's class "factor256" but I'm having trouble honouring the
`strictly` argument.  I've defined

is.unsorted.factor256 <- function(x, na.rm = FALSE, strictly = FALSE) {
  strictly
}

i.e. the class is sorted iff strictly = TRUE

However, the strictly argument appears to be ignored

x <- integer(2)
class(x) <- "factor256"

is.unsorted(x)  # FALSE [expected]
is.unsorted(x, strictly = TRUE)  # FALSE [unexpected]

The method is definitely being dispatched as when I change the function to

is.unsorted.factor256 <- function(x, na.rm = FALSE, strictly = FALSE) {
  cat("dispatching\n")
  strictly
}

I see the dispatch:

is.unsorted(ff, strictly = T)
#> dispatching
#> [1] FALSE

and

> methods("is.unsorted")
[1] is.unsorted.factor256
see '?methods' for accessing help and source code

I note that if I omit the na.rm = argument I will get the intended
result (I was drawn to the solution by noting the .Internal call has
omitted it) but I'm wondering whether this is correct.


Best,


Hugh Parsonage.