[R] can a function alter the "..." argument and passed the result to another function?

Dan Kelley dan.kelley at dal.ca
Fri Dec 19 01:27:04 CET 2008

Is there a way a function ('parent', say) can manipulate the ...  
argument, and then pass the manipulated value into another function  
('child', say) that it calls?

What I'm trying to do is to use some plotting defaults within 'parent'  
that are not part of parent's argument list, but to let the use over- 
ride these defaults if they choose.  A sketch is below.

parent <- function(stuff, ...) {
   dots <- list(...)
   if (!"type" in names(list)) dots$type='p'
   plot(stuff, unlist(dots))  # or alist()? or what?

I know, I can just make "type" be a formal argument of 'parent', and  
I'm happy to do that, but I'm still in the learning stages with R, and  
so I'm trying to become more familiar with as much R syntax as I can,  
even if I end up doing things differently later on.

D. Kelley
Oceanography Department, Dalhousie University
Halifax, Nova Scotia, Canada

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