Allow '0' cache prefix

Author: MGatner

system/Cache/Handlers/FileHandler.php

@@ -71,7 +71,7 @@ public function __construct(Cache $config)
 		}
 
 		$this->mode   = $config->file['mode'] ?? 0640;
-		$this->prefix = $config->prefix ?: '';
+		$this->prefix = (string) $config->prefix;
 	}
 
 	//--------------------------------------------------------------------

system/Cache/Handlers/MemcachedHandler.php

@@ -58,7 +58,7 @@ class MemcachedHandler implements CacheInterface
 	 */
 	public function __construct(Cache $config)
 	{
-		$this->prefix = $config->prefix ?: '';
+		$this->prefix = (string) $config->prefix;
 
 		if (! empty($config))
 		{

system/Cache/Handlers/PredisHandler.php

@@ -58,7 +58,7 @@ class PredisHandler implements CacheInterface
 	 */
 	public function __construct(Cache $config)
 	{
-		$this->prefix = $config->prefix ?: '';
+		$this->prefix = (string) $config->prefix;
 
 		if (isset($config->redis))
 		{

system/Cache/Handlers/RedisHandler.php

@@ -58,7 +58,7 @@ class RedisHandler implements CacheInterface
 	 */
 	public function __construct(Cache $config)
 	{
-		$this->prefix = $config->prefix ?: '';
+		$this->prefix = (string) $config->prefix;
 
 		if (! empty($config))
 		{

system/Cache/Handlers/WincacheHandler.php

@@ -37,7 +37,7 @@ class WincacheHandler implements CacheInterface
 	 */
 	public function __construct(Cache $config)
 	{
-		$this->prefix = $config->prefix ?: '';
+		$this->prefix = (string) $config->prefix;
 	}
 
 	//--------------------------------------------------------------------

user_guide_src/source/libraries/caching.rst

@@ -57,7 +57,7 @@ more complex, multi-server setups.
 **$prefix**
 
 If you have more than one application using the same cache storage, you can add a custom prefix
-here that is prepended to all key names.
+string here that is prepended to all key names.
 
 **$file**