constant

constant returns the constant value for a given string:

.. code-block:: twig

{{ some_date|date(constant('DATE_W3C')) }}
{{ constant('Namespace\\Classname::CONSTANT_NAME') }}

You can read constants from object instances as well:

.. code-block:: twig

{{ constant('RSS', date) }}

Retrieve the fully qualified class name of an object:

.. code-block:: twig

{{ constant('class', date) }}

Use the defined test to check if a constant is defined:

.. code-block:: twig

{% if constant('SOME_CONST') is defined %}
    ...
{% endif %}