[R] Communicating with R through a named pipe: display refresh problem

[Parker Jones]

> Rather, non-interactive R does not run an event loop.  The usual way 
> around this is to use a pty, as R run from a pty is considered to be 
> interactive.
> 
> (Whether a fifo and a named pipe are the same concept is moot: some OSes 
> have one and not the other.)
> 
> The plan is to use threads in due course to handle X11 events.
> 
I agree threads is the way to go.

In the meantime, I also tried a looping server which doesn't block on reads to a pipe.  This still doesn't refresh the display but if R has a command to refresh the display then that will probably solve the problem.

# based on http://tolstoy.newcastle.edu.au/R/help/01c/2886.html
stream <- fifo("R_pipe", "r", blocking=FALSE,)
repeat
 {
  a <- readLines(stream)
  if(length(a) != 0)
   {
    e <- try(eval(parse(text = a)))
    if (inherits(e, "try-error"))
     {
      # error handling code here
      cat("Error", "\n")
     }
   }
 }