[hoc-users] performSelectorWithObject problems

[Christian H. <chr...@gm...>]

Hi again,

now that the installation finally succeeded, the real problems begin...

I wrote a small application with a "Quit" button. Before the  
application displays that it quits, I want it to perform some fancy  
action: call the dummy method "dummy" on itself. (Ok, this is just a  
simplified version of what I really want...)

To make it more interesting,  it uses the "performSelectorWithObject"  
method on itself. When I do this, my application crashes.

In Objective-C it looks like this (and it works):

- (IBAction)quit:(id)sender
{
     [self performSelector: @selector(dummy:) withObject: self];
     [actionLabel setStringValue: [NSString stringWithCString:  
"Quit!" encoding: NSMacOSRomanStringEncoding]];
}
- (void)dummy:(NSObject*)ignored
{
}

In Haskell, I started like this:
I declared a selector for my dummy in my Selectors.hs:
$(declareSelector "dummy:" [t| forall a. NSObject a -> IO ()|])

Then I added an instance method:
$(exportClass [...] InstanceMethod Selectors.info_dummy])

inet_dummy _ self = return ()

inet_quit _ self =
     self # performSelectorWithObject (getSelectorForName "dummy:") self
     -- self # inet_dummy self   <-- that works, but is not what I want!
     self #. _actionLabel >>= setStringValue (toNSString ("Quit!"))  
-- replacing this line with just a "return ()" works as well!!!

Now, the selector is found ((self # respondsToSelector  
(getSelectorForName "dummy:")) returns true), but when I try to  
perform the selector, and change the label text afterwards, the  
application crashes. Am I doing something wrong?

(Remark: I did not use the -O compiler option.)

By the way, is there a way to get MVar concurrency working together  
with HOC? Can I use MVars just like that (after telling Cocoa to run  
thread-safe)? Do I have to use POSIX threads?

Regards,
Chris