[slime-devel] input not getting through

[Helmut Eller]

* Daniel Patru [2005-11-04 03:27+0100] writes:

> Anyway to make this work? (I'm trying to do some processing in between
> user input.)

As Pascal Bourguignon said, you should flush the output buffer.

But you also need to be careful with LISTEN.  Actually reading from
*standard-input* in SLIME is a bit weird.  LISTEN (in SLIME) returns
true if there is any buffered input, e.g. if you call READ-CHAR the
Emacs REPL buffer switches to "read-mode" and the next time you press
return the entire line gets buffered.

Also note that the REPL buffer is usually not in "read-mode" and that
pressing return (usually) doesn't write anything to the input buffer.
Keep an eye on the modeline, there is an indicator [read] if the REPL
is in read-mode.

Some other issues are:

 - buffered input is discarded before evaluation requests i.e. about
   every time when SLIME prints a prompt. (This means that LISTEN
   returns false most of the time.)

 - if you want to send an "end-of-transmission" (like C-d in a
   terminal) you have to press C-u RET.

Your example works a bit better if you write it like this:

  (defun prompt ()
    (do ((line nil (read)))
        ((eq line 'q))
      (when line (print line))
      (print '>)
      (finish-output)
      (sleep 1)))

Helmut.