add a macro to make a retcall on the parent class

include/tr/class.h

@@ -262,6 +262,22 @@
 		iface->method(object, ##__VA_ARGS__);                      \
 	} while(0)
 
+/*
+ * Like retcall but this calls the implementation of the direct parent
+ * class of this object.
+ *
+ * \see TR_RETCALL
+ */
+#define TR_PARENTRETCALL(object,_iface,method,ret,...)             \
+	do {                                                           \
+		struct i_##_iface * iface;                                 \
+		TR_class_ptr pc_class = TR_GET_CLASS((object));            \
+		assert(TR_HAS_PARENT(pc_class));                           \
+		_TR_CALL(pc_class->parent, _iface, method, ##__VA_ARGS__); \
+		ret = iface->method(object, ##__VA_ARGS__);                \
+	} while(0)
+
+
 /**
  * Definition of the metadata structures and symbols used to
  * manage classe.