How is notify used in Cocoa?

Elements Oxygene
1

Is there an example of how to use notify in Cocoa? The documentation on the RemObjects site still says it’s a .NET-only feature, but that’s no longer true as of 7.0. This is the kind of thing that drives me NUTS about trying to get up to speed in Oxygene.

2

Agreed, we need to get the docs updated on that.Essentially, notify will integrate with Cocoa’s KVO. here’s the raw info that will eventually make it into docs:

Documentation

Echoes

INotifyPropertyChanging is implemented (if the mscorlib has it)
and INotifyPropertyChanged is implemented. If the base type already implements it it expects there to be a “raise” to the property for PropertyChanged/PropertyChanging (else it fails).

Nougat

Notify works by A: Ignoring if it’s there unless it has a name (because the framework handles that case automatically via KVO), then it implements the automaticallyNotifiesObserversForKey, returns false for the values with a special notify value, otherwise returns the inherited value. For each property with a notify with name, it writes a willChangeValueForKey before, didChangeValueForKey after (only if the value did change)

Cooper

There’s no special interface in Cooper for this, instead it’s a pattern:

   private java.beans.PropertyChangeSupport changes := new java.beans.PropertyChangeSupport(this);
 
   protected void firePropertyChange(string name, object old, object new) 
   {
      changeSupport.firePropertyChange(name, old, new);
   }

    public void addPropertyChangeListener(PropertyChangeListener listener) {
        changes.addPropertyChangeListener(listener);
    }

    public void removePropertyChangeListener(PropertyChangeListener listener) {
        changes.removePropertyChangeListener(listener); 
    }

    public void setSampleProperty(String value) {
        String oldValue = sampleProperty;
        sampleProperty = value;
        firePropertyChangeListener("sampleproperty", oldValue, sampleProperty);
    }

When the base class has the add/remove it will expect a protected fire to exist, else it will fail.

3

Thanks, Marc. As much as it pains me to be critical, for most users “if it’s not documented, it doesn’t exist yet.”

4

Yeah, hear ya.