.. versionadded:: 1.12.1 constant now accepts object instances as the second argument.
.. versionadded:: 1.28 Using ``constant`` with the ``defined`` test was added in Twig 1.28.
constant
returns the constant value for a given string:
{{ some_date|date(constant('DATE_W3C')) }}
{{ constant('Namespace\\Classname::CONSTANT_NAME') }}
As of 1.12.1 you can read constants from object instances as well:
{{ constant('RSS', date) }}
Use the defined
test to check if a constant is defined:
{% if constant('SOME_CONST') is defined %}
...
{% endif %}