Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] unbuffered input
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Alan Schmitt <alan.schmitt@p...>
Subject: Re: [Caml-list] unbuffered input: a solution
* Alan Schmitt (alan.schmitt@polytechnique.org) wrote:
> Hi,
> 
> I've been looking at this for about one hour, and I seem to get stuck: 
> how can I do unbuffered input in caml ? I want a program to block until 
> a char is entered. I tried input_char and Unix.read (without 
> and with Unix.select), to no avail. I do not know if it is caml, the 
> libc, or the terminal that is buffering.
> 
> Any hint on how to do this ?

Thanks to Owen Gunden and the unison code, I found the following 
solution:

let term = Unix.tcgetattr Unix.stdin in
try
  Unix.tcsetattr 
    Unix.stdin
    Unix.TCSANOW 
    {term with Unix.c_icanon = false; 
               Unix.c_echo = false;
               Unix.c_vmin = 1;};
  while true do
    let c = input_char stdin in
    Printf.printf "read %c\n" c;
    flush stdout
  done;
  (* restore the terminal in its initial state *)
  Unix.tcsetattr Unix.stdin Unix.TCSANOW term
with
| e -> Unix.tcsetattr Unix.stdin Unix.TCSANOW term; raise e

Is there no simpler solution ?

And by the way, I see that unison does a
Sys.catch_break true
to transform the break signal into an exception, but I did not need it 
here (doing ctrl-c does restore the terminal in a good state). I'm 
curious as to why this is the case.

Alan Schmitt

-- 
The hacker: someone who figured things out and made something cool happen.

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners