From: Iain Dooley <idoo4002@...>
Date: 2005-08-29T19:33:07+09:00
Subject: Re: catching segmentation faults from Ruby



ts wrote:
>>>>>>"I" == Iain Dooley <idoo4002@mail.usyd.edu.au> writes:
> 
> 
> I> will crash ruby if there is no child of parent with name "widgetName". i 
> I> know that there is rb_funcall_protect that allows you to trap errors, 
> I> but the problem is that i'm not doing an rb_funcall. the functions are 
> I> being called from with Qt/Ruby bindings. is there a way that i can trap 
> I> all errors from the ruby interpreter to prevent segfaults in dynamically 
> I> edited code from crashing the program?
> 
>  Look at rb_eval_string_protect(), rb_protect()
> 

in fact, the problem here is that i'm not calling the functions from 
within my code. what i do is create a new Qt::Object class using 
rb_funcall, then i look within Qt/Ruby bindings to find the underlying 
QObject (C++ object), then bind the slots present in this object to a 
dynamically loaded .ui interface file using QWidgetFactory::create().

this returns a class of object QWidget. i then create a new Qt::Widget 
class using rb_funcall, find the underlying object and switch the 
pointer to the object returned by QWidgetFactory::create(). This means 
that you can create .ui file in Qt Designer and then load it into an 
application runner and write the code that controls the GUI behaviour at 
runtime.

it works beautifully, but because i am not doing an eval_string or a 
funcall to execute the code (it is all handled within Smoke and Qt/Ruby) 
i can't simply put rb_protect() around it. my main routine looks like this:

#include <qapplication.h>
#include "runner.h"
#include <ruby.h>

int main( int argc, char *argv[] )
{
     QApplication app( argc, argv );
     ruby_init();
     Runner *runner = new Runner();
     app.setMainWidget( runner );
     runner->show();
     return app.exec();
}

would it be possible, do you think to have:

#include <qapplication.h>
#include "runner.h"
#include <ruby.h>

int main( int argc, char *argv[] )
{
     int ret = 2;

     QApplication app( argc, argv );
     ruby_init();
     Runner *runner = new Runner();
     app.setMainWidget( runner );
     runner->show();

     while(ret==2)
         ret = executeProgram(app);

     return ret;
}

int executeProgram(QApplication &app)
{
     int ret = 0;

     try
     {
         ret = app.exec();
     }

     catch(RubyException *exc)
     {
         //DISPLAY SOME ERROR MESSAGE OR MODAL DIALOG
         ret = 2;
     }

     return ret;
}

does such a RubyException exists? is there some general exception that 
will come floating up unhandled out of my application to meet me?

cheers

ian