def get_classes_names(self, update=False):
        """
        Return the names of classes

        :param update: True indicates to recompute the list.
                       Maybe needed after using a MyClass.set_name().
        :rtype: a list of string
        """
        if self.classes_names is None or update:
            self.classes_names = [i.get_name() for i in self.get_classes()]
        return self.classes_names