Below is a system defined delegate:
//Represents methods that will handle various routed events that //track property value changes.
public delegate void RoutedPropertyChangedEventHandler<T>(object sender, RoutedPropertyChangedEventArgs<T> e);
below is partial definition of RoutedPropertyChangedEventArgs<T>:
public class RoutedPropertyChangedEventArgs<T> : RoutedEventArgs
{
// Summary:
// Initializes a new instance of the System.Windows.RoutedPropertyChangedEventArgs<T>
// class, with provided old and new values.
//
// Parameters:
// oldValue:
// Previous value of the property, prior to the event being raised.
//
// newValue:
// Current value of the property at the time of the event.
public RoutedPropertyChangedEventArgs(T oldValue, T newValue);
…
}
e.g. Slider's ValueChanged event is of this type:
Slider s = new Slider();
s.ValueChanged += new System.Windows.RoutedPropertyChangedEventHandler<double>(s_ValueChanged);
static void s_ValueChanged(object sender, System.Windows.RoutedPropertyChangedEventArgs<double> e)
{
// both e.OldValue and e.NewValue are "double" type.
}
