private function _addInstanceDefinition(__InstanceDefinition &$instance_definition)
{
if ($instance_definition->validate()) {
$instance_id = $instance_definition->getId();
if (!key_exists($instance_id, $this->_instance_definitions)) {
$this->_instance_definitions[__InstanceDefinition::SCOPE_ALL][$instance_id] =& $instance_definition;
$this->_instance_definitions[$instance_definition->getScope()][$instance_id] =& $instance_definition;
} else {
throw new __ConfigurationException('Double definition of instance "' . $instance_id . '"');
}
}
}
