#``constant`` > Twig 1.13.1 加入。``constant``接收对象实例作为它的第二个参数。 ``constant`` checks if a variable has the exact same value as a constant. You can use either global constants or class constants: {% if post.status is constant('Post::PUBLISHED') %} the status attribute is exactly the same as Post::PUBLISHED {% endif %} You can test constants from object instances as well: {% if post.status is constant('PUBLISHED', post) %} the status attribute is exactly the same as Post::PUBLISHED {% endif %}