Session Cache Limiting

To avoid users seeing stale data, it's common for session-enabled resources to be

sent with headers that disable caching. For this purpose PHP Sessions has the

``sessions.cache_limiter`` option, which determines which headers, if any, will be

sent with the response when the session in started.

Upon construction,

:class:`Symfony\\Component\\HttpFoundation\\Session\\Storage\\NativeSessionStorage`

sets this global option to ``""`` (send no headers) in case the developer wishes to

use a :class:`Symfony\\Component\\HttpFoundation\\Response` object to manage

response headers.

.. caution::

If you rely on PHP Sessions to manage HTTP caching, you *must* manually set the

``cache_limiter`` option in

:class:`Symfony\\Component\\HttpFoundation\\Session\\Storage\\NativeSessionStorage`

to a non-empty value.

For example, you may set it to PHP's default value during construction:

Example usage::