How to expand an ellipsis (…) argument without evaluating it in R

Question

I need a function that accepts an arbitrary number of arguments and stores them in a variable as an expression without evaluating them. I managed to do it with match.c

Answer 1

The most idiomatic way is:

f <- function(x, y, ...) {
  match.call(expand.dots = FALSE)$`...`
}

Answer 2

The ultimate intended outcome is slightly vague (could you clarify a bit?). However, this may be helpful:

foo2 <- function(...) {
  expr <- as.list(substitute(list(...)))[-1L]
  class(expr) <- "expression"
  expr
}

example:

foo2(x=bla, y=2)
# expression(x = bla, y = 2)

Answer 3

Using . from plyr as a prototype

foo <-   function (...) 
  {
  as.expression(as.list(match.call()[-1]))
  }