Merge branch '3.4' into 4.3

* 3.4:
  [Translation] create custom message formatter.

Author: javiereguiluz

components/translation/custom_message_formatter.rst

@@ -0,0 +1,38 @@
+.. index::
+    single: Translation; Create Custom Message formatter
+
+Create a Custom Message Formatter
+=================================
+
+The default message formatter provided by Symfony solves the most common needs
+when translating messages, such as using variables and pluralization. However,
+if your needs are different, you can create your own message formatter.
+
+Message formatters are PHP classes that implement the
+:class:`Symfony\\Component\\Translation\\Formatter\\MessageFormatterInterface`::
+
+
+    use Symfony\Component\Translation\Formatter\MessageFormatterInterface;
+
+    class MyCustomMessageFormatter implements MessageFormatterInterface
+    {
+        public function format($message, $locale, array $parameters = [])
+        {
+            // ... format the message according to your needs
+
+            return $message;
+        }
+    }
+
+Now, pass an instance of this formatter as the second argument of the translator
+to use it when translating messages::
+
+    use Symfony\Component\Translation\Translator;
+
+    $translator = new Translator('fr_FR', new IntlMessageFormatter());
+    $message = $translator->trans($originalMessage, $translationParameters);
+
+If you want to use this formatter to translate all messages in your Symfony
+application, define a service for the formatter and use the
+:ref:`translator.formatter <reference-framework-translator-formatter>` option
+to set that service as the default formatter.

reference/configuration/framework.rst

@@ -227,6 +227,7 @@ Configuration
   * :ref:`default_path <reference-translator-default_path>`
   * :ref:`enabled <reference-translator-enabled>`
   * `fallbacks`_
+  * `formatter`_
   * `logging`_
   * :ref:`paths <reference-translator-paths>`
 
@@ -2090,6 +2091,20 @@ for a given key. The logs are made to the ``translation`` channel and at the
 ``debug`` for level for keys where there is a translation in the fallback
 locale and the ``warning`` level if there is no translation to use at all.
 
+.. _reference-framework-translator-formatter:
+
+formatter
+.........
+
+**type**: ``string`` **default**: ``translator.formatter.default``
+
+The ID of the service used to format translation messages. The service class
+must implement the :class:`Symfony\\Component\\Translation\\Formatter\\MessageFormatterInterface`.
+
+.. seealso::
+
+    For more details, see :doc:`/components/translation/custom_message_formatter`.
+
 .. _reference-translator-paths:
 
 paths