/// <summary>
/// Observes a property that is used to determine if this command can execute, and if it implements
/// INotifyPropertyChanged it will automatically call DelegateCommandBase.RaiseCanExecuteChanged on property changed
/// notifications.
/// </summary>
/// <param name="canExecuteExpression">The property expression. Example: ObservesCanExecute((o) => PropertyName).</param>
/// <returns>The current instance of DelegateCommand</returns>
protected internal void ObservesCanExecuteInternal(Expression <Func <object, bool> > canExecuteExpression)
{
CanExecuteMethod = canExecuteExpression.Compile();
AddPropertyToObserve(PropertySupport.ExtractPropertyNameFromLambda(canExecuteExpression));
HookInpc(canExecuteExpression.Body as MemberExpression);
}