Add Cache::remember()

This method provides a really simple approach to read-through caching.
A callable or Closure can be used to provide results when the cache is
empty.

lib/Cake/Cache/Cache.php

@@ -542,4 +542,27 @@ class Cache {
 		throw new CacheException(__d('cake_dev', 'Invalid cache group %s', $group));
 	}
 
+/**
+ * Provides the ability to easily do read-through caching.
+ *
+ * When called if the $key is not set in $config, the $callable function
+ * will be invoked. The results will then be stored into the cache config
+ * at key.
+ *
+ * @param string $key The cache key to read/store data at.
+ * @param callable $callable The callable that provides data in the case when
+ *   the cache key is empty.
+ * @param string $config The cache configuration to use for this operation.
+ *   Defaults to default.
+ */
+	public static function remember($key, $callable, $config = 'default') {
+		$existing = self::read($key, $config);
+		if ($existing !== false) {
+			return $existing;
+		}
+		$results = call_user_func($callable);
+		self::write($key, $results, $config);
+		return $results;
+	}
+
 }

lib/Cake/Test/Case/Cache/CacheTest.php

@@ -27,6 +27,8 @@ App::uses('Cache', 'Cache');
  */
 class CacheTest extends CakeTestCase {
 
+	protected $_count = 0;
+
 /**
  * setUp method
  *
@@ -491,4 +493,28 @@ class CacheTest extends CakeTestCase {
 		$this->assertEquals('test_file_', $settings['prefix']);
 		$this->assertEquals(strtotime('+1 year') - time(), $settings['duration']);
 	}
+
+/**
+ * test remember method.
+ *
+ * @return void
+ */
+	public function testRemember() {
+		$expected = 'This is some data 0';
+		$result = Cache::remember('test_key', [$this, 'cacher'], 'default');
+		$this->assertEquals($expected, $result);
+
+		$this->_count = 1;
+		$result = Cache::remember('test_key', [$this, 'cacher'], 'default');
+		$this->assertEquals($expected, $result);
+	}
+
+/**
+ * Method for testing Cache::remember()
+ *
+ * @return string
+ */
+	public function cacher() {
+		return 'This is some data ' . $this->_count;
+	}
 }