How handle the next parameter of invoke method in a PMC ?

[François PERRAD]

In Lua, a metamethod '__call' is needed.
So in the base PMC, I want write something like this:

    void* invoke(void* next) {
        PMC *meth = find_meth(INTERP, SELF, "__call");
        /*
         * Here, I need to insert SELF as first argument,
         * in the argument list carried by next structure.
         */
        next = VTABLE_invoke(INTERP, meth, next);
        /*
         * Here, if the result list carried by next is null,
         * I need to insert default value : an LuaNil PMC.
         */
        return next;
    }

The real code is in languages/lua/pmc/luaany.pmc.
2 TODO tests are ready in languages/lua/t/metatable.t.

Thanks.

François.