🚀 go-pugleaf

In article <BywsHq.Hv4@cmcl2.nyu.edu> dario@cns.nyu.edu (Dario Ringach,  
x3941) writes:
>I have a button sending an -abortCalculation message to an object which
>is engaged in a loop...  Something like this:
>
>-compute:sender
>{
>  notAborted = YES;
>  while(notAborted) {
>    .... 
>  }
>  return self;
>}
>
>-abortCalculation:sender
>{
>  notAborted = NO;
>  return self;
>}
>
>Needless to say... it doesn't work.  
>How can I make it to work?


Your abortCaclulation: message is the target of a button.  It will get  
called as a result of a user action -- namely, the user clicking on the  
button.
However, your app is busy in its while(notAborted) loop, so it can't  
respond to user actions.  You have to give the app the opportunity to  
respond to events.

You can do this in one of several different ways, but probably the easiest  
and most appropriate for this situation is to use a modal session.

A modal session allows you to run your loop while still processing events.   
You can only respond to events in one window with this method.  That's  
probably okay, since all you care about is the window with the stop button  
in it.
This would end up looking something like this:

- compute:sender
{
  NXModalSession session;
  
  [NXApp beginModalSession:&session for:theWindow];  // theWindow is the  
window with the stop button in it. 
  while ([NXApp runModalSession:&session] == NX_RUNCONTINUES) {
    /* Do the rest of your computation loop here */
    }
  [NXApp endModalSession:&session];
  return self;
}

- abortCalculation:sender
{
  [NXApp stopModal];
  return self;
}


For a slightly different way to make an abortable procedure, check out the  
description of NXUserAborted().  This will let you break out of a loop if  
the user hits cmd - period.  

Hope this helps,

-- josh