add ability to call interface methods with return value

include/class.h

@@ -40,19 +40,28 @@
  * @TODO: actually i use gcc feature ## for variadoc... think about
  * a way to make this standard.
  */
-#define CALL(object,_iface,method,...)                                            \
-	do {                                                                          \
-		class_ptr           class = class_getClass((object));                     \
-		struct i_##_iface * iface;                                                \
-		if (class->init)	class->init();                                        \
-		iface = (struct i_##_iface *)class_getInterface(&class, &i_##_iface);     \
-		while ((NULL == iface || NULL == iface->method) && HAS_PARENT(class)) {   \
-			class = class->parent;                                                \
-			if (class->init)	class->init();                                    \
-			iface = (struct i_##_iface *)class_getInterface(&class, &i_##_iface); \
-		};                                                                        \
-		assert(NULL != iface->method);                                            \
-		iface->method(object, ##__VA_ARGS__);                                     \
+#define _CALL(object,_iface,method,...)                                       \
+	class_ptr           class = class_getClass((object));                     \
+	struct i_##_iface * iface;                                                \
+	if (class->init)	class->init();                                        \
+	iface = (struct i_##_iface *)class_getInterface(&class, &i_##_iface);     \
+	while ((NULL == iface || NULL == iface->method) && HAS_PARENT(class)) {   \
+		class = class->parent;                                                \
+		if (class->init)	class->init();                                    \
+		iface = (struct i_##_iface *)class_getInterface(&class, &i_##_iface); \
+	};                                                                        \
+	assert(NULL != iface->method);
+
+#define CALL(object,_iface,method,...)               \
+	do {                                             \
+		_CALL(object, _iface, method, ##__VA_ARGS__); \
+		iface->method(object, ##__VA_ARGS__);        \
+	} while(0)
+
+#define RETCALL(object,_iface,method,ret,...)        \
+	do {                                             \
+		_CALL(object, _iface, method, ##__VA_ARGS__); \
+		ret = iface->method(object, ##__VA_ARGS__);  \
 	} while(0)