> f <- function(...) {
+ dotArgList <- substitute(list(...))
+ dotArgList
+ }
> f(cat("foo\n"), stop("Oops"), warning("Hmm"))
list(cat("foo\n"), stop("Oops"), warning("Hmm"))
> # i.e., no argument was evaluated
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-devel-boun...@r-project.org
> [mailto:r-devel-boun...@r-project.org] On Behalf Of Peter Danenberg
> Sent: Wednesday, May 25, 2011 11:06 AM
> To: Duncan Murdoch
> Cc: r-devel@r-project.org
> Subject: Re: [Rd] External special functions (SPECIALSXP)
>
> > However, if you don't want to evaluate the arguments, just pass
> > substitute(arg) to your function instead of arg.
>
> Thanks, Duncan; the problem is, I'm trying to substitute on `...' and
> I don't think I can access `...' without inadvertently evaluating it.
>
> I'm trying to write a debugging function which, given any number of
> expressions, prints the expression next to its evaluation.
>
> This is trivial to do in the single arity case:
>
> debug <- function(expression) {
> cat(substitute(expression), expression, "\n")
> }
>
> a <- 2
> debug(a)
>
> a 2
>
> but I'm not sure how to make it work with variable arity without
> resorting to SPECIALSXP.
>
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> https://stat.ethz.ch/mailman/listinfo/r-devel
>
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