From: Fredrik Jagenheim <fredde@...>
Date: 2003-08-25T05:21:12+09:00
Subject: fxRuby and errors

Hi,

I just started to make my first 'real' application using Ruby and
fxRuby as a GUI.

I've noticed that if I kill my application using Ctrl-C instead of
killing it through the windowmanager, I don't get any errors raised.

My application runs in a thread separate from the GUI thread, as shown
here:

---===---

application = FXApp.new('Foo')

window = Window.new(application)

application.create

thread = Thread.new {
    runTrueApplication
}

application.run

thread.join

===---===

If 'runTrueApplication' raises something I'd think would be considered
a 'fatal' error, namely that it tries to call a method that doesn't
exist (raises NoSuchMethod, IIRC) I don't get to know about that
error. Only after I kill the application by closing the window I get
the error message printed to stderr. Interrupting the process with
Ctrl-C just kills the program and nothing gets printed out.

This leads me to think that I've missed something important about how
Threads and Exceptions play together. Could someone please straight
this out for me? I guess thread.join is the key? It collects all
thrown exceptions? Is there a way for me to know about thrown errors
/before/ thread.join? Apart from;
[...]
thread = Thread.new {
    begin
        runTrueApplication
    rescue
        puts "Something happened that you should know about: #{$!}"
    end
}

TIA,
//F, switches between {} and begin/end all the time. ;)