Avoid mutating state

src/Silex/ViewListenerWrapper.php

@@ -39,13 +39,13 @@ class ViewListenerWrapper
     public function __invoke(GetResponseForControllerResultEvent $event)
     {
         $controllerResult = $event->getControllerResult();
-        $this->callback = $this->app['callback_resolver']->resolveCallback($this->callback);
+        $callback = $this->app['callback_resolver']->resolveCallback($this->callback);
 
-        if (!$this->shouldRun($controllerResult)) {
+        if (!$this->shouldRun($callback, $controllerResult)) {
             return;
         }
 
-        $response = call_user_func($this->callback, $controllerResult, $event->getRequest());
+        $response = call_user_func($callback, $controllerResult, $event->getRequest());
 
         if ($response instanceof Response) {
             $event->setResponse($response);
@@ -54,15 +54,15 @@ class ViewListenerWrapper
         }
     }
 
-    protected function shouldRun($controllerResult)
+    protected function shouldRun($callback, $controllerResult)
     {
-        if (is_array($this->callback)) {
-            $callbackReflection = new \ReflectionMethod($this->callback[0], $this->callback[1]);
-        } elseif (is_object($this->callback) && !$this->callback instanceof \Closure) {
-            $callbackReflection = new \ReflectionObject($this->callback);
+        if (is_array($callback)) {
+            $callbackReflection = new \ReflectionMethod($callback[0], $callback[1]);
+        } elseif (is_object($callback) && !$callback instanceof \Closure) {
+            $callbackReflection = new \ReflectionObject($callback);
             $callbackReflection = $callbackReflection->getMethod('__invoke');
         } else {
-            $callbackReflection = new \ReflectionFunction($this->callback);
+            $callbackReflection = new \ReflectionFunction($callback);
         }
 
         if ($callbackReflection->getNumberOfParameters() > 0) {