The original code was not intended to be fully finished.
It was just to give the idea so I left out the error checking.
Adding such a check is just a matter of adding an if
statement to check the pmatch for NA:
wrapper <- function(...) {
args <- list(...)
if (length(args)) {
nf <- names(formals(lowlevel))
idx <- pmatch(names(args), nf)
if (any(is.na(idx)))
stop(paste("Invalid names used:", names(args)[is.na(idx)]))
nams <- nf[idx]
args <- replace(list(longname = 2), nams, args)
}
do.call("lowlevel", args)
}
wrapper(long = 3)
wrapper(junk = 5)
On 3/7/06, Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> On 3/7/2006 9:42 AM, Gabor Grothendieck wrote:
> > Try this:
> >
> >
> > wrapper <- function(...) {
> > args <- list(...)
> > if (length(args)) {
> > nf <- names(formals(lowlevel))
> > nams <- nf[pmatch(names(args), nf)]
> > args <- replace(list(longname = 2), nams, args)
> > }
> > do.call("lowlevel", args)
> > }
> >
> > Here is a test:
> >
> >> wrapper()
> > longname = 1
> >> wrapper(longname = 34)
> > longname = 34
> >> wrapper(long = 34)
> > longname = 34
>
> Thanks, that's getting close, but it doesn't quite handle errors cleanly:
>
> > wrapper(junk=3)
> Error in lowlevel(longname = 2, "NA" = 3) :
> unused argument(s) (NA ...)
>
> It looks like I'll need something fairly elaborate.
>
> Duncan Murdoch
>
> > On 3/7/06, Duncan Murdoch <[EMAIL PROTECTED]> wrote:
> >> I'm writing wrappers for some functions that change some of the default
> >> arguments. I'd rather not list all of the arguments for the low level
> >> functions because there are about a dozen wrapper functions, and about
> >> 20 arguments to lowlevel. Instead I'm trying something like this:
> >>
> >> lowlevel <- function(longname = 1) {
> >> cat("longname = ", longname, "\n")
> >> }
> >>
> >> wrapper <- function(...) {
> >> newargs <- list(longname = 2)
> >> newargs[names(list(...))] <- list(...)
> >> do.call("lowlevel", newargs)
> >> }
> >>
> >> This almost works:
> >>
> >> > wrapper()
> >> longname = 2
> >> > wrapper(longname = 3)
> >> longname = 3
> >>
> >> But it fails if I try to use partial argument matching:
> >>
> >> > wrapper(long=4)
> >> Error in lowlevel(longname = 2, long = 4) :
> >> unused argument(s) (long ...)
> >>
> >> because long isn't matched to longname. Is there a reasonable way to do
> >> this (e.g. using pmatch or charmatch) other than listing all the low
> >> level arguments in the argument list to wrapper?
> >>
> >> Duncan Murdoch
> >>
> >> ______________________________________________
> >> R-devel@r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-devel
> >>
> >
> > ______________________________________________
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
>
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