How to assign from a function which returns more than one value?

return-two-values.R

# (https://stackoverflow.com/questions/1826519/how-to-assign-from-a-function-which-returns-more-than-one-value)
':=' <- function(lhs, rhs) {
  frame <- parent.frame()
  lhs <- as.list(substitute(lhs))
  if (length(lhs) > 1)
    lhs <- lhs[-1]
  if (length(lhs) == 1) {
    do.call(`=`, list(lhs[[1]], rhs), envir=frame)
    return(invisible(NULL)) 
  }
  if (is.function(rhs) || is(rhs, 'formula'))
    rhs <- list(rhs)
  if (length(lhs) > length(rhs))
    rhs <- c(rhs, rep(list(NULL), length(lhs) - length(rhs)))
  for (i in 1:length(lhs))
    do.call(`=`, list(lhs[[i]], rhs[[i]]), envir=frame)
  return(invisible(NULL)) 
}

functionReturningTwoValues <- function() {
  return(list(1, matrix(0, 2, 2)))
}
c(a, b) := functionReturningTwoValues()