Message-ID: <4545E762.9010000 at laposte.net>
Date: Mon, 30 Oct 2006 12:52:02 +0100
From: Matthieu Dubuget <matthieu.dubuget at laposte.net>
Reply-To: matthieu.dubuget at laposte.net
MIME-Version: 1.0
To: lablgtk at math.nagoya-u.ac.jp
Subject: Callbacks and threads
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Hello.

I have a button b in a little application, which I want to trig function
f (val f: unit -> unit) when clicked.
f reads some value from hardware: it lasts 2~3 s.

As a first try, I just did
 b#connect#clicked ~callback:f

It works as expected.

I know would like to:
- modify IHM (change cursor, disable buttons...) with : val active :
bool -> unit
- call f
- revert IHM modifications

I tried:
b#connect#clicked ~callback:(
  fun () ->
    active false;
    f ();
    active true;
)

f is called ok, except that:
- cursor change is not displayed during computation (seems like I have
to give control back to the main loop for this to happen?)
- if another button is clicked during the computation, the corresponding
callback is called after f has returned.

I then tried:
b#connect#clicked ~callback:(
(fun () ->
  active false ;
  ignore (Thread.create (fun () ->
    f ();
    active true) ())
)

Unfortunately, this way, f is nether executed?

Obviously,
~callback: (fun ()-> ignore (Thread.create (fun () ->
                                   lire_eeprom ();
                                  active true) ()))
Does not work...

What is the right thing to do (I mean except from stopping programming
and drinking a good fresh beer)?

Salutations

Matt