multassign.R

'%=%' = function(l, r, ...)
  UseMethod('%=%')

  # Binary Operator
  '%=%.lbunch' = function(l, r, ...) {
    Envir = as.environment(-1)

    if (length(r) > length(l))
      warning("Right side has more args than left side. Only first ", length(l), " arguments used.")

    if (length(l) > length(r))  {
      warning("Left side has more arguments than right side. Right side will be repeated.")
      r <- extendToMatch(r, l)
    }

    for (n in 1:length(l)) {
      do.call('<-', list(l[[n]], r[[n]]), envir=Envir)
    }
  }

  # Used if LHS is larger than RHS
  extendToMatch <- function(source, destin) {
    s <- length(source)
    d <- length(destin)

    # Assume that destin is a length when it is a single number and source is not
    if(d==1 && s>1 && !is.null(as.numeric(destin)))
      d <- destin

    dif <- d - s
    if (dif > 0) {
      source <- rep(source, ceiling(d/s))[1:d]
    }
    return (source)
  } 

g = function(...) {
  List = as.list(substitute(list(...)))[-1L]
  class(List) = 'lbunch'
  return(List)
}