How to overload the assignment operator?

Dear all,

what is the proper way to make the assignment operator generic and define methods depending on the class of the assigned value?

Best regards

Jens Oehlschl?gel

P.S. I vaguely remember that this was possible in S+. In R I tried to no avail: 

  # using this like h<-1:3 gives Error: in `<-.default`(h, 1:3) : invalid (do_set) left-hand side to assignment
  "<-.default" <- get("<-") 

  # using this does fail on subassignments like: h <- 1:3 ; h[1] <- 7 (h still is 1:3)
  "<-.default" <- function(x, value){
    assign(deparse(substitute(x)), value, parent.frame())
    invisible(x)
  }

  # this seems to work
  "<-" <- function(x, value){
    UseMethod("<-", value)
  }

  # whenever the assigned value has class 'ff' I want to do execute something like
  "<-.ff" <- function(x, value){
    y <- clone(value)
    assign(deparse(substitute(x)), y, parent.frame())
    y
  }