How to round a value in Twig

You can use parameter substitution in the twig globals section of the config:

Parameter config:

parameters:
    app.version: 0.1.0

Twig config:

twig:
    globals:
        version: '%app.version%'

Twig template:

{{ version }}

This method provides the benefit of allowing you to use the parameter in ContainerAware classes as well, using:

$container->getParameter('app.version');

As of Twig 1.5, the correct answer is to use the dump function. It is fully documented in the Twig documentation. Here is the documentation to enable this inside Symfony2.

{{ dump(user) }}