Making CacheEngine an abstract class, and updating FileEngine to incl…

…ude the not implemented methods.

cake/libs/cache.php

@@ -486,7 +486,7 @@ public static function settings($name = null) {
  * @package       cake
  * @subpackage    cake.cake.libs
  */
-class CacheEngine {
+abstract class CacheEngine {
 
 /**
  * Settings of current engine instance
@@ -520,32 +520,27 @@ public function init($settings = array()) {
  * Garbage collection
  *
  * Permanently remove all expired and deleted data
- *
+ * @return void
  */
-	public function gc() {
-	}
+	abstract public function gc();
 
 /**
  * Write value for a key into cache
  *
  * @param string $key Identifier for the data
  * @param mixed $value Data to be cached
- * @param mixed $duration How long to cache the data, in seconds
+ * @param mixed $duration How long to cache for.
  * @return boolean True if the data was succesfully cached, false on failure
  */
-	public function write($key, &$value, $duration) {
-		trigger_error(sprintf(__('Method write() not implemented in %s'), get_class($this)), E_USER_ERROR);
-	}
+	abstract public function write($key, $value, $duration);
 
 /**
  * Read a key from the cache
  *
  * @param string $key Identifier for the data
  * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
  */
-	public function read($key) {
-		trigger_error(sprintf(__('Method read() not implemented in %s'), get_class($this)), E_USER_ERROR);
-	}
+	abstract public function read($key);
 
 /**
  * Increment a number under the key and return incremented value
@@ -554,36 +549,32 @@ public function read($key) {
  * @param integer $offset How much to add
  * @return New incremented value, false otherwise
  */
-	public function increment($key, $offset = 1) {
-		trigger_error(sprintf(__('Method increment() not implemented in %s'), get_class($this)), E_USER_ERROR);
-	}
+	abstract public function increment($key, $offset = 1);
+
 /**
  * Decrement a number under the key and return decremented value
  *
  * @param string $key Identifier for the data
  * @param integer $value How much to substract
  * @return New incremented value, false otherwise
  */
-	public function decrement($key, $offset = 1) {
-		trigger_error(sprintf(__('Method decrement() not implemented in %s'), get_class($this)), E_USER_ERROR);
-	}
+	abstract public function decrement($key, $offset = 1);
+
 /**
  * Delete a key from the cache
  *
  * @param string $key Identifier for the data
  * @return boolean True if the value was succesfully deleted, false if it didn't exist or couldn't be removed
  */
-	public function delete($key) {
-	}
+	abstract public function delete($key);
 
 /**
  * Delete all keys from the cache
  *
  * @param boolean $check if true will check expiration, otherwise delete all
  * @return boolean True if the cache was succesfully cleared, false otherwise
  */
-	public function clear($check) {
-	}
+	abstract public function clear($check);
 
 /**
  * Cache Engine settings

cake/libs/cache/file.php

@@ -110,7 +110,7 @@ public function gc() {
  * @param mixed $duration How long to cache the data, in seconds
  * @return boolean True if the data was succesfully cached, false on failure
  */
-	public function write($key, &$data, $duration) {
+	public function write($key, $data, $duration) {
 		if ($data === '' || !$this->_init) {
 			return false;
 		}
@@ -227,6 +227,26 @@ public function clear($check) {
 		return true;
 	}
 
+/**
+ * Not implemented
+ *
+ * @return void
+ * @throws BadMethodCallException
+ */
+	public function decrement($key, $offset = 1) {
+		throw new BadMethodCallException('Files cannot be atomically decremented.');
+	}
+
+/**
+ * Not implemented
+ *
+ * @return void
+ * @throws BadMethodCallException
+ */
+	public function increment($key, $offset = 1) {
+		throw new BadMethodCallException('Files cannot be atomically incremented.');
+	}
+
 /**
  * Get absolute file for a given key
  *