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
>>
>
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