[Rubycocoa-talk] NSApplication base class for capturing exceptions

[Jonathan P. <jp...@dc...>]

Hi all,

My patch for bridging exceptions between Ruby and Objective C appears  
to be in the CVS trunk. To go along with this, here's a base-class to  
be used in place of NSApplication that will pop up an NSAlert when a  
ruby exception occurs. The alert has 'Continue' and 'Abort' buttons.

To use this class, it's necessary to adjust 'rb_main.rb to use  
RBCApplication in place of NSApplication:

if $0 == __FILE__ then
   rb_main_init
   OSX::ns_import "RBCApplication"
   OSX::RBCApplication.sharedApplication
   OSX.NSApplicationMain(0, nil)
end

Hope this is of some use.
Jonathan




// RBCApplication.h
#import <Cocoa/Cocoa.h>

@interface RBCApplication : NSApplication {
}
@end

// RBCApplication.m
@implementation RBCApplication

-(void)notifyRubyException:(NSException*)exc
{
     static BOOL handling;
     if (handling) {
         NSLog(@"Got an exception %@ while handling another one!",exc);
         return;
     }
     handling = YES;

     NSMutableString *bs = nil;
     NSArray *backtrace = [[exc userInfo] objectForKey: @"backtrace"];

     if (backtrace) {
         bs = [NSMutableString string];;
         [bs appendString: @"Backtrace: \n"];

         NSString *resources = [[NSBundle mainBundle] resourcePath];

         unsigned int i, count = [backtrace count];
         for (i = 0; i < count; i++) {
             NSString *path = [backtrace objectAtIndex:i];
             if ([path hasPrefix: resources]) {
                 path = [path substringFromIndex:[resources length]+1];
             }
             [bs appendFormat: @"  %@\n", path];
         }
     }

     NSString *s = [NSString stringWithFormat: @"An unhandled Ruby  
exception occurred:\nName: %@\nReason: %@\n%@",
         [[exc name] substringFromIndex: [@"RBException_" length]],
         [exc reason],
         bs ? (NSString*)bs : @""];

     NSAlert *alert = [[NSAlert alloc] init];
     [alert addButtonWithTitle: @"Continue"];
     [alert addButtonWithTitle: @"Abort"];
     [alert setMessageText: @"Ruby Exception"];
     [alert setInformativeText: s];

     if ([alert runModal] == NSAlertSecondButtonReturn) {
         exit(1);
     }
     [alert release];

     handling = NO;
}

-(void)run
{
     while (1) {
         NS_DURING
             [super run];
             NS_VOIDRETURN;
         NS_HANDLER
             if ([[localException name] hasPrefix: @"RBException_"]) {
                 [self notifyRubyException: localException];
             } else {
                 [localException raise];
             }
         NS_ENDHANDLER;
     }
}
@end