improve code

Author: fenric

src/ReferenceResolver.php

@@ -78,7 +78,7 @@ public function toRequestHandler($reference) : RequestHandlerInterface
 
         list($class, $method) = $this->normalizeReference($reference);
 
-        if (isset($class, $method) && method_exists($class, $method)) {
+        if (isset($class) && isset($method) && method_exists($class, $method)) {
             return new CallableRequestHandler([$this->resolveClass($class), $method]);
         }
 
@@ -107,7 +107,7 @@ public function toMiddleware($reference) : MiddlewareInterface
 
         list($class, $method) = $this->normalizeReference($reference);
 
-        if (isset($class, $method) && method_exists($class, $method)) {
+        if (isset($class) && isset($method) && method_exists($class, $method)) {
             return new CallableMiddleware([$this->resolveClass($class), $method]);
         }
 
@@ -164,9 +164,11 @@ private function stringifyReference($reference) : string
     /**
      * Resolves the given class
      *
-     * @param string $class
+     * @param class-string<T> $class
      *
-     * @return object
+     * @return T
+     *
+     * @template T
      */
     private function resolveClass(string $class)
     {

src/Route.php

@@ -38,8 +38,10 @@ class Route implements RouteInterface
      * Server Request attribute name for the route
      *
      * @var string
+     *
+     * @deprecated 2.11.0 Use the RouteInterface::ATTR_ROUTE constant.
      */
-    public const ATTR_NAME_FOR_ROUTE = '@route';
+    public const ATTR_NAME_FOR_ROUTE = self::ATTR_ROUTE;
 
     /**
      * Server Request attribute name for the route name
@@ -396,7 +398,7 @@ public function withAddedAttributes(array $attributes) : RouteInterface
      */
     public function handle(ServerRequestInterface $request) : ResponseInterface
     {
-        $request = $request->withAttribute(self::ATTR_NAME_FOR_ROUTE, $this);
+        $request = $request->withAttribute(self::ATTR_ROUTE, $this);
 
         /** @todo Must be removed from the 3.0.0 version */
         $request = $request->withAttribute(self::ATTR_NAME_FOR_ROUTE_NAME, $this->name);

src/RouteInterface.php

@@ -23,6 +23,15 @@
 interface RouteInterface extends RequestHandlerInterface
 {
 
+    /**
+     * Request attribute name for the route instance
+     *
+     * @var string
+     *
+     * @since 2.11.0
+     */
+    public const ATTR_ROUTE = '@route';
+
     /**
      * Gets the route name
      *