public function add(ilAssQuestionSolutionComparisonExpression $expression) { $expression->setDb($this->db); $expression->setQuestionId($this->getQuestionId()); $expression->setSkillBaseId($this->getSkillBaseId()); $expression->setSkillTrefId($this->getSkillTrefId()); $this->expressions[$expression->getOrderIndex()] = $expression; }