[R] Obtaining names of ``...'' arguments.

[Deepayan Sarkar]

foo <- function(...) as.character(match.call(expand.dots = FALSE)$"...")

should give you the names a a character vector.

--- Rolf Turner <rolf at math.unb.ca> wrote:
> This may be an FAQ, but a (perfunctory) search failed to turn it up.
> 
> Suppose I have a function foo(...){<something>} and I want to obtain,
> inside foo, the names of items comprising the ``...''.  E.g. if I
> call
> 
>  foo(melvin,clyde,irving)
>
> I want to be able to loop through the ``...'' and successively obtain
> the text strings "melvin", "clyde", and "irving".
> 
> Is there any way to do this?
> 
> I know that if I had a function foo(x,y,z){<something>}, and I called
> foo(melvin,clyde,irving), I could get the text strings I want by
> means of
> 
>  deparse(substitute(x)) # Giving "melvin".
>  deparse(substitute(y)) # Giving "clyde".
>  deparse(substitute(z)) # Giving "irving".
> 
> but if foo() is to take an arbitrary number of arguments then this
> sort of syntax is not available.
> 
>      cheers,
> 
>       Rolf Turner
>       rolf at math.unb.ca
>
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