.. note::
Before writing your own extensions, have a look at the Twig official
- extension repository: http://github.com/twigphp/Twig-extensions.
+ extension repository: https://github.com/twigphp/Twig-extensions.
An extension is a class that implements the following interface::
``Twig_Test_NodeTestCase``. Examples can be found in the Twig repository
`tests/Twig/Node`_ directory.
-.. _`spl_autoload_register()`: http://www.php.net/spl_autoload_register
-.. _`rot13`: http://www.php.net/manual/en/function.str-rot13.php
+.. _`spl_autoload_register()`: https://secure.php.net/spl_autoload_register
+.. _`rot13`: https://secure.php.net/manual/en/function.str-rot13.php
.. _`tests/Twig/Fixtures`: https://github.com/twigphp/Twig/tree/master/test/Twig/Tests/Fixtures
.. _`tests/Twig/Node`: https://github.com/twigphp/Twig/tree/master/test/Twig/Tests/Node