Expanding partial names
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
On 3/7/06, Duncan Murdoch <murdoch at stats.uwo.ca> 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
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