/// <summary>
/// Raises the PropertyChanged event if needed, and broadcasts a
/// PropertyChangedMessage using the Messenger instance (or the
/// static default instance if no Messenger instance is available).
/// </summary>
/// <typeparam name="T">The type of the property that
/// changed.</typeparam>
/// <param name="propertyExpression">An expression identifying the property
/// that changed.</param>
/// <param name="oldValue">The property's value before the change
/// occurred.</param>
/// <param name="newValue">The property's value after the change
/// occurred.</param>
/// <param name="broadcast">If true, a PropertyChangedMessage will
/// be broadcasted. If false, only the event will be raised.</param>
protected virtual void RaisePropertyChanged <T>(Expression <Func <T> > propertyExpression, T oldValue, T newValue, bool broadcast)
{
PropertyChangedEventHandler propertyChangedHandler = base.PropertyChangedHandler;
if ((propertyChangedHandler != null) || broadcast)
{
string propertyName = BindableObject.GetPropertyName <T>(propertyExpression);
if (propertyChangedHandler != null)
{
propertyChangedHandler(this, new PropertyChangedEventArgs(propertyName));
}
if (broadcast)
{
this.Broadcast <T>(oldValue, newValue, propertyName);
}
}
}