diff --git a/m-funcobj.h b/m-funcobj.h
index 2653121c..f557c31c 100644
--- a/m-funcobj.h
+++ b/m-funcobj.h
@@ -83,7 +83,6 @@
  * FIXME: How to factorize reasonnably well between the definitions?
  */
 
-
 /* Specialization of the OPLIST in function if there is at least one member or not */
 #define FUNC_OBJ_INS_NO_ATTR_OPLIST(name, ...)                          \
   (NAME(name), TYPE(M_C(name, _t)),                                     \
@@ -195,8 +194,39 @@
 
 /* Specialization of the definition a function object instance of name 'name'
  * with mandatory member attribute.
+ * First inject oplist in member attributes.
  */
 #define FUNC_OBJ_INS_ATTR_DEF(name, base_name, param_list, callback_core, ...) \
+  FUNCOBJI_INS_ATTR_DEF_P2(name, base_name, param_list, callback_core, FUNCOBJI_INJECT_GLOBAL(__VA_ARGS__) )
+
+/* Inject the oplist within the list of arguments */
+#define FUNCOBJI_INJECT_GLOBAL(...)               \
+  M_MAP_C(FUNCOBJI_INJECT_OPLIST_A, __VA_ARGS__)
+/* Transform (x, type) into (x, type, oplist) if there is global registered oplist 
+   or (x, type, M_DEFAULT_OPLIST) if there is no global one,
+   or keep (x, type, oplist) if oplist was already present */
+#define FUNCOBJI_INJECT_OPLIST_A( duo_or_trio )   \
+  FUNCOBJI_INJECT_OPLIST_B duo_or_trio
+#define FUNCOBJI_INJECT_OPLIST_B( f, ... )                                \
+  M_IF_NARGS_EQ1(__VA_ARGS__)( (f, __VA_ARGS__, M_GLOBAL_OPLIST_OR_DEF(__VA_ARGS__)()), (f, __VA_ARGS__) )
+
+// Test if all third argument of all arguments is an oplist
+#define FUNCOBJI_IF_ALL_OPLIST(...)                               \
+  M_IF(M_REDUCE(FUNCOBJI_IS_OPLIST_P, M_AND, __VA_ARGS__))
+// Test if the third argument is an oplist
+#define FUNCOBJI_IS_OPLIST_P(a)                   \
+  M_OPLIST_P(M_RET_ARG3 a)
+
+/* Validate the oplist before going further */
+#define FUNCOBJI_INS_ATTR_DEF_P2(name, base_name, param_list, callback_core, ...) \
+  FUNCOBJI_IF_ALL_OPLIST(__VA_ARGS__)(FUNCOBJI_INS_ATTR_DEF_P3, FUNCOBJI_INS_ATTR_DEF_FAILURE)(name, base_name, param_list, callback_core, __VA_ARGS__)
+
+/* Stop processing with a compilation failure */
+#define FUNCOBJI_INS_ATTR_DEF_FAILURE(name, base_name, param_list, callback_core, ...) \
+  M_STATIC_FAILURE(M_LIB_NOT_AN_OPLIST, "(FUNC_OBJ_INS_DEF): at least one of the given argument is not a valid oplist: " #__VA_ARGS__)
+
+/* Expand the Function Object with members */
+#define FUNCOBJI_INS_ATTR_DEF_P3(name, base_name, param_list, callback_core, ...) \
   typedef struct M_C(name, _s) {                                        \
     M_C(base_name, _callback_t) callback;                               \
     M_MAP(FUNC_OBJ_INS_ATTR_STRUCT, __VA_ARGS__)                        \
@@ -245,6 +275,7 @@
     , /* END OF INIT METHOD */ )                                        \
 
 
+
 /* Helper macros */
 #define FUNC_OBJ_BASE_TYPE(name, num, type)     \
   typedef type M_C4(name, _param_, num, _t);
diff --git a/m-tuple.h b/m-tuple.h
index 9cc0af89..be709dbf 100644
--- a/m-tuple.h
+++ b/m-tuple.h
@@ -35,6 +35,7 @@
 #define TUPLE_DEF2(name, ...)                   \
   TUPLEI_DEF2_P1( (name, TUPLEI_INJECT_GLOBAL(__VA_ARGS__)) )
 
+
 /* Define the oplist of a tuple.
    USAGE: TUPLE_OPLIST(name[, oplist of the first type, ...]) */
 #define TUPLE_OPLIST(...)                                          \
@@ -42,7 +43,8 @@
   (TUPLEI_OPLIST_P1((__VA_ARGS__, M_DEFAULT_OPLIST )),		   \
    TUPLEI_OPLIST_P1((__VA_ARGS__ )))
 
-/* Return an array suitable for the _cmp_order function.
+
+/* Return an array suitable for the WIP _cmp_order function.
    As compound literals are not supported in C++,
    provide a separate definition for C++ using initializer_list
    (shall be constexpr, but only supported in C++14).
@@ -71,9 +73,13 @@ namespace m_tuple {
 
 /********************************** INTERNAL ************************************/
 
+/* Inject the oplist within the list of arguments */
 #define TUPLEI_INJECT_GLOBAL(...)               \
   M_MAP_C(TUPLEI_INJECT_OPLIST_A, __VA_ARGS__)
 
+/* Transform (x, type) into (x, type, oplist) if there is global registered oplist 
+   or (x, type, M_DEFAULT_OPLIST) if there is no global one,
+   or keep (x, type, oplist) if oplist was already present */
 #define TUPLEI_INJECT_OPLIST_A( duo_or_trio )   \
   TUPLEI_INJECT_OPLIST_B duo_or_trio
 
@@ -83,7 +89,23 @@ namespace m_tuple {
 // Deferred evaluation
 #define TUPLEI_DEF2_P1(...)                       TUPLEI_DEF2_P2 __VA_ARGS__
 
-#define TUPLEI_DEF2_P2(name, ...)                 \
+// Test if all third argument of all arguments is an oplist
+#define TUPLEI_IF_ALL_OPLIST(...)                               \
+  M_IF(M_REDUCE(TUPLEI_IS_OPLIST_P, M_AND, __VA_ARGS__))
+// Test if the third argument is an oplist
+#define TUPLEI_IS_OPLIST_P(a)                   \
+  M_OPLIST_P(M_RET_ARG3 a)
+
+/* Validate the oplist before going further */
+#define TUPLEI_DEF2_P2(name, ...)                                        \
+  TUPLEI_IF_ALL_OPLIST(__VA_ARGS__)(TUPLEI_DEF2_P3, TUPLEI_DEF2_FAILURE)(name, __VA_ARGS__)
+
+/* Stop processing with a compilation failure */
+#define TUPLEI_DEF2_FAILURE(name, ...)                                   \
+  M_STATIC_FAILURE(M_LIB_NOT_AN_OPLIST, "(TUPLE_DEF2): at least one of the given argument is not a valid oplist: " #__VA_ARGS__)
+
+/* Define the tuple */
+#define TUPLEI_DEF2_P3(name, ...)                 \
   TUPLE_DEFINE_TYPE(name, __VA_ARGS__)            \
   TUPLE_DEFINE_ENUM(name, __VA_ARGS__)            \
   TUPLEI_IF_ALL(INIT, __VA_ARGS__)                \
diff --git a/m-variant.h b/m-variant.h
index 59133432..be45ca52 100644
--- a/m-variant.h
+++ b/m-variant.h
@@ -36,6 +36,7 @@
 #define VARIANT_DEF2(name, ...)                                         \
   VARIANTI_DEF2_P1( (name, VARIANTI_INJECT_GLOBAL(__VA_ARGS__)) )
 
+
 /* Define the oplist of a variant.
    USAGE: VARIANT_OPLIST(name[, oplist of the first type, ...]) */
 #define VARIANT_OPLIST(...)                                        \
@@ -46,9 +47,13 @@
 
 /********************************** INTERNAL ************************************/
 
+/* Inject the oplist within the list of arguments */
 #define VARIANTI_INJECT_GLOBAL(...)               \
   M_MAP_C(VARIANTI_INJECT_OPLIST_A, __VA_ARGS__)
 
+/* Transform (x, type) into (x, type, oplist) if there is global registered oplist 
+   or (x, type, M_DEFAULT_OPLIST) if there is no global one,
+   or keep (x, type, oplist) if oplist was already present */
 #define VARIANTI_INJECT_OPLIST_A( duo_or_trio )   \
   VARIANTI_INJECT_OPLIST_B duo_or_trio
 
@@ -58,7 +63,23 @@
 // Deferred evaluation
 #define VARIANTI_DEF2_P1(...)                  VARIANTI_DEF2_P2 __VA_ARGS__
 
-#define VARIANTI_DEF2_P2(name, ...)                    \
+// Test if all third argument of all arguments is an oplist
+#define VARIANTI_IF_ALL_OPLIST(...)                               \
+  M_IF(M_REDUCE(VARIANTI_IS_OPLIST_P, M_AND, __VA_ARGS__))
+// Test if the third argument is an oplist
+#define VARIANTI_IS_OPLIST_P(a)                   \
+  M_OPLIST_P(M_RET_ARG3 a)
+
+/* Validate the oplist before going further */
+#define VARIANTI_DEF2_P2(name, ...)                                        \
+  VARIANTI_IF_ALL_OPLIST(__VA_ARGS__)(VARIANTI_DEF2_P3, VARIANTI_DEF2_FAILURE)(name, __VA_ARGS__)
+
+/* Stop processing with a compilation failure */
+#define VARIANTI_DEF2_FAILURE(name, ...)                                   \
+  M_STATIC_FAILURE(M_LIB_NOT_AN_OPLIST, "(VARIANT_DEF2): at least one of the given argument is not a valid oplist: " #__VA_ARGS__)
+
+/* Define the variant */
+#define VARIANTI_DEF2_P3(name, ...)                    \
   VARIANTI_DEFINE_TYPE(name, __VA_ARGS__)              \
   VARIANTI_DEFINE_INIT(name, __VA_ARGS__)              \
   VARIANTI_DEFINE_CLEAR(name, __VA_ARGS__)             \