Re: [Rd] Attributes of 1st argument in ...

From: Olaf Mersmann <>
Date: Sat, 03 Jul 2010 00:15:57 +0200

Hi Daniel,

On 02.07.2010, at 23:26, Daniel Murphy wrote:
> I am trying to get an attribute of the first argument in a call to a
> function whose formal arguments consist of dots only and do something, e.g.,
> call 'cbind', based on the attribute
> f<- function(...) {get first attribute; maybe or maybe not call 'cbind'}
> I thought of (ignoring "deparse.level" for the moment)
> f<-function(...) {x <- attr(list(...)[[1L]], "foo"); if (x=="bar")
> cbind(...) else x}

what about using the somewhat obscure ..1 syntax? This version runs quite a bit faster for me:

 g <- function(...) {
   x <- attr(..1, "foo")
   if (x == "bar")

but it will be hard to quantify how this pans out for your unless we know how many and what size and type the arguments are.

Olaf mailing list Received on Fri 02 Jul 2010 - 22:18:18 GMT

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