Can I swap variables inside a function using pointers in R?

Question

Here is a silly (maybe only in my mind) way to accomplish my goal:

A <- "This is a test."
B <- "This is the answer."
swap <- function(item1,item2) {
  tmp   <- item2
  item2 <- item1
  item1 <- tmp
  return(list(item1,item2))
}
AB <- swap(A,B)
A <- AB[[1]]
B <- AB[[2]]

But I'm considering something similar to the C code following:

void swap(int *a, int *b)
{
    int iTemp ;
    iTemp = *a;
    *a = *b;
    *b = iTemp;

}

My motivations:

• My real data is quite large, e.g. 5k*5k matrix, so the assignment of the existing variable in the iteration twice, inside the function and outside the function, must be time squandering.
• The closest question on the SO is this one, but just like the OP in the question, my R session also has lots of objects: I'm working with Rmpi, and each slave will have a great number of variables.
• In my humble opinion, R is written in C, so R may have pointers like C does, while I can't find much on the net surprisingly.

Answer 1

How about this; this just assigns to the parent environment.

A <- "This is a test."
B <- "This is the answer."

swap <- function(item1, item2) {
  tmp <- item1
  assign(deparse(substitute(item1)), item2, pos = 1)
  assign(deparse(substitute(item2)), tmp, pos = 1)
}

swap(A, B)
A
#[1] "This is the answer."
B
#[1] "This is a test.