Starting to implement translations caching

src/I18n/I18n.php

@@ -55,7 +55,7 @@ public static function translators() {
 			return static::$_collection;
 		}
 
-		return static::$_collection = new TranslatorLocator(
+		return static::$_collection = new TranslatorRegistry(
 			new PackageLocator,
 			new FormatterLocator([
 				'sprintf' => function() {

src/I18n/TranslatorRegistry.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         3.0.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\I18n;
+
+use Aura\Intl\TranslatorLocator;
+use Serializable;
+
+/**
+ * 
+ */
+class TranslatorRegistry extends TranslatorLocator implements Serializable {
+
+	public function serialize() {
+		return serialize($this->registry);
+	}
+
+	public function unserialize($data) {
+		$this->registry = unserialize($data);
+	}
+
+}

tests/TestCase/I18n/I18nTest.php

@@ -265,4 +265,26 @@ public function testBasicContextFunction() {
 		);
 	}
 
+	public function testTranslatorsCache() {
+		I18n::translator('custom', 'en_US', function() {
+			$package = new Package();
+			$package->setMessages([
+				'Cow' => 'Le moo',
+				'Foo' => 'Bar'
+			]);
+			return $package;
+		});
+
+		$default = I18n::translator();
+		$this->assertEquals('%d is 1 (po translated)', $default->translate('%d = 1'));
+
+		$translators = I18n::translators();
+		$serialized = serialize($translators);
+		$restored = unserialize($serialized);
+
+		$this->assertEquals(
+			$restored->get('default', 'en_US')->translate('%d = 1'),
+			$default->translate('%d = 1')
+		);
+	}
 }