[R] do.call("+", ...)

[Gabor Grothendieck]

On 17 Nov 2006 15:59:24 +0100, Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:
> Robin Hankin <r.hankin at noc.soton.ac.uk> writes:
>
> > On 17 Nov 2006, at 14:14, Peter Dalgaard wrote:
> >
> > [snip]
> >
> > >
> > > so a+b+c is really (a+b)+c and I was calculating a+(b+c). That's
> > > actually a little bit harder because you don't get help from argument
> > > matching:
> > >
> > > "++" <- function(...) if ((n <- nargs()) == 1) ..1 else {
> > >     l <- list(...)
> > >     do.call("++",l[-n]) + l[[n]]
> > > }
> > >
> >
> >
> > Aha, the dreaded "..1" argument.   Where do I look for documentation
> > on this?
> >
> > [It is mentioned twice in The R Language Definition, but I'm no wiser]
>
> It's just the first of the ... arguments, essentially list(...)[[1]],
> except for lazy evaluation details. The second one is ..2, and
> so forth.

What are you referring to when writing "except for lazy function details"?