R help - Jan 2025 - Extracting specific arguments from "..."

Consider:

f1 <- function(...){
  one <- list(...)[['a']]
  two <- ...elt(match('a', ...names()))
  c(one, two)
}
## Here "..." is an argument list with "a" somewhere in it,
but in an
unknown position.
> f1(b=5, a = 2, c=7)
[1] 2 2

Which is better for extracting a specific named argument, one<- or
two<- ?  Or a third alternative that is better than both?
Comments and critiques welcome.

Cheers,
Bert

I would use two because it does not force the evaluation of the other
arguments in the ... list.



On Sun, Jan 5, 2025, 13:00 Bert Gunter <bgunter.4567 at gmail.com> wrote:
> Consider:
>
> f1 <- function(...){
>   one <- list(...)[['a']]
>   two <- ...elt(match('a', ...names()))
>   c(one, two)
> }
> ## Here "..." is an argument list with "a" somewhere in
it, but in an
> unknown position.
>
> > f1(b=5, a = 2, c=7)
> [1] 2 2
>
> Which is better for extracting a specific named argument, one<- or
> two<- ?  Or a third alternative that is better than both?
> Comments and critiques welcome.
>
> Cheers,
> Bert
>
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