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[Components][DependencyInjection] do not reference services in parameters #4222

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73 changes: 0 additions & 73 deletions components/dependency_injection/parameters.rst
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Expand Up @@ -336,76 +336,3 @@ To disable this behavior, use the ``string`` type:

This is not available for YAML and PHP, because they already have built-in
support for the PHP keywords.

Syntax for Referencing Services
-------------------------------

You can of course also reference services, which looks a bit different in
each format. You can configure the behavior if the referenced service does
not exist. By default, an exception is thrown when a non-existent service
is referenced.

YAML
~~~~

Start the string with ``@`` or ``@?`` to reference a service in YAML.

* ``@mailer`` references the ``mailer`` service. If the service does not
exist, an exception will be thrown;
* ``@?mailer`` references the ``mailer`` service. If the service does not
exist, it will be ignored;

.. code-block:: yaml

parameters:
# if 'my_mailer' service isn't defined, an exception will be raised
foo: @my_mailer

# if 'my_logger' service isn't defined, 'bar' will be null
bar: @?my_logger

.. tip::

Use ``@@`` to escape the ``@`` symbol in YAML. ``@@mailer`` will be
converted into the string ``"@mailer"`` instead of referencing the
``mailer`` service.

XML
~~~

In XML, use the ``service`` type. The behavior if the service does not exist
can be specified using the ``on-invalid`` argument. By default, an exception
is thrown. Valid values for ``on-invalid`` are ``null`` (uses ``null`` in place
of the missing service) or ``ignored`` (very similar, except if used on a
method call, the method call is removed).

.. code-block:: xml

<parameters>
<!-- if 'my_mailer' service isn't defined, an exception will be raised -->
<parameter key="foo" type="service" id="my_mailer" />

<!-- if 'my_logger' service isn't defined, 'bar' will be null -->
<parameter key="bar" type="service" id="my_logger" on-invalid="null" />
</parameters>

PHP
~~~

In PHP, you can use the
:class:`Symfony\\Component\\DependencyInjection\\Reference` class to reference
a service. The invalid behavior is configured using the second constructor
argument and constants from
:class:`Symfony\\Component\\DependencyInjection\\ContainerInterface`.

.. code-block:: php

use Symfony\Component\DependencyInjection\Reference;

// if 'my_mailer' service isn't defined, an exception will be raised
$container->setParameter('foo', new Reference('my_mailer'));

// if 'my_logger' service isn't defined, 'bar' will be null
$container->setParameter('bar', new Reference('my_logger',
ContainerInterface::NULL_ON_INVALID_REFERENCE
));