sol::property is implemented for usertypes now

sol::this_state is  a transparent argument that gets the current state at any position in any callback
sol::variadic_args allows a person to get something that can reference the "rest of the arguments", though it doesn't enforce that it has to be the last argument

Closes #57
Closes #59
Closes #60

sol/function_types.hpp

@@ -33,7 +33,6 @@
 #include "resolve.hpp"
 
 namespace sol {
-
 template <typename Sig, typename... Ps>
 struct function_arguments {
     std::tuple<Ps...> params;

sol/function_types_basic.hpp

@@ -80,7 +80,7 @@ struct upvalue_member_function {
 template <int N, typename R, typename M, typename V>
 int set_assignable(std::false_type, lua_State* L, M&, V&) {
     lua_pop(L, N);
-    return luaL_error(L, "cannot write to this type: copy assignment/constructor not available");
+    return luaL_error(L, "sol: cannot write to this type: copy assignment/constructor not available");
 }
 
 template <int N, typename R, typename M, typename V>
@@ -98,7 +98,7 @@ int set_variable(std::true_type, lua_State* L, M& mem, V& var) {
 template <int N, typename R, typename M, typename V>
 int set_variable(std::false_type, lua_State* L, M&, V&) {
     lua_pop(L, N);
-    return luaL_error(L, "cannot write to a const variable");
+    return luaL_error(L, "sol: cannot write to a const variable");
 }
 
 template<typename T, typename Function>

sol/function_types_core.hpp

@@ -26,6 +26,108 @@
 #include <memory>
 
 namespace sol {
+template <typename RSig = void, typename WSig = void>
+struct member_property {
+    typedef std::conditional_t<std::is_void<RSig>::value, detail::empty, RSig> R;
+    typedef std::conditional_t<std::is_void<WSig>::value, detail::empty, WSig> W;
+
+    R read;
+    W write;
+
+    member_property(R read, W write) : read(std::move(read)), write(std::move(write)) {}
+
+    template <typename T, typename Arg>
+    void write_if(std::true_type, T& mem, Arg&& arg) {
+        write(mem, arg);
+    }
+
+    template <typename T, typename Arg>
+    void write_if(std::false_type, T&, Arg&&) {
+        // This is a fatal error if we get here...
+        // Should never happen but...
+        // Crash horrifically, for safety?
+        std::abort();
+    }
+
+    template <typename T, typename Arg>
+    void operator()(T& mem, Arg&& arg) {
+        write_if(meta::Not<std::is_void<WSig>>(), mem, arg);
+    }
+
+    template <typename T>
+    decltype(auto) read_if(std::true_type, T& mem) {
+        return read(mem);
+    }
+
+    template <typename T>
+    decltype(auto) read_if(std::false_type, T&) {
+        typedef typename meta::bind_traits<WSig>::template arg_at<1> Arg;
+       typedef std::add_pointer_t<std::remove_reference_t<Arg>> pret;
+        // This is a fatal error if we get here...
+        // Should never happen but...
+        // Crash horrifically, for safety?
+        std::abort();
+        return *pret();
+    }
+
+    template <typename T>
+    decltype(auto) operator()(T& mem) {
+        return read_if(meta::Not<std::is_void<RSig>>(), mem);
+    }
+};
+
+template <typename R, typename T>
+inline decltype(auto) property( R(T::* readfunc )() const) {
+    auto rf = [readfunc](T& mem) -> R {return (mem.*readfunc)();};
+    return member_property<decltype(rf)>(std::move(rf), detail::empty());
+}
+
+template <typename R, typename T>
+inline decltype(auto) property( R(T::* readfunc )()) {
+    auto rf = [readfunc](T& mem) -> R {return (mem.*readfunc)();};
+    return member_property<decltype(rf)>(std::move(rf), detail::empty());
+}
+
+template <typename R, typename T, typename Arg>
+inline decltype(auto) property(R(T::* writefunc)(Arg)) {
+    auto wf = [writefunc](T& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<void, decltype(wf)>(detail::empty(), std::move(wf));
+}
+
+template <typename R, typename T, typename Arg>
+inline decltype(auto) property(R(T::* writefunc)(Arg) const) {
+    auto wf = [writefunc](T& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<void, decltype(wf)>(detail::empty(), std::move(wf));
+}
+
+template <typename RR, typename RT, typename WR, typename WT, typename Arg>
+inline decltype(auto) property(RR(RT::* readfunc)(), WR(WT::* writefunc)(Arg)) {
+    auto rf = [readfunc](RT& mem) -> RR {return (mem.*readfunc)();};
+    auto wf = [writefunc](WT& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<decltype(rf), decltype(wf)>(std::move(rf), std::move(wf));
+}
+
+template <typename RR, typename RT, typename WR, typename WT, typename Arg>
+inline decltype(auto) property(RR(RT::* readfunc)() const, WR(WT::* writefunc)(Arg)) {
+    auto rf = [readfunc](RT& mem) -> RR {return (mem.*readfunc)();};
+    auto wf = [writefunc](WT& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<decltype(rf), decltype(wf)>(std::move(rf), std::move(wf));
+}
+
+template <typename RR, typename RT, typename WR, typename WT, typename Arg>
+inline decltype(auto) property(RR(RT::* readfunc)(), WR(WT::* writefunc)(Arg) const) {
+    auto rf = [readfunc](RT& mem) -> RR {return (mem.*readfunc)();};
+    auto wf = [writefunc](WT& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<decltype(rf), decltype(wf)>(std::move(rf), std::move(wf));
+}
+
+template <typename RR, typename RT, typename WR, typename WT, typename Arg>
+inline decltype(auto) property(RR(RT::* readfunc)() const, WR(WT::* writefunc)(Arg) const) {
+    auto rf = [readfunc](RT& mem) -> RR {return (mem.*readfunc)();};
+    auto wf = [writefunc](WT& mem, Arg arg) {(mem.*writefunc)(std::forward<Arg>(arg));};
+    return member_property<decltype(rf), decltype(wf)>(std::move(rf), std::move(wf));
+}
+
 namespace function_detail {
 template <typename T>
 struct implicit_wrapper {
@@ -48,35 +150,62 @@ inline decltype(auto) cleanup_key() {
 template<typename T, typename Func, typename = void>
 struct functor {
     typedef meta::bind_traits<Func> traits_type;
-    typedef typename traits_type::args_type args_type;
+    typedef meta::pop_front_type_t<typename traits_type::args_type> args_type;
     typedef typename traits_type::return_type return_type;
-    static const std::size_t arity = traits_type::arity;
+    typedef meta::tuple_element_t<0, typename traits_type::args_tuple_type> Arg0;
-
+    typedef std::conditional_t<std::is_pointer<Func>::value || std::is_class<Func>::value, Func, std::add_pointer_t<Func>> function_type;
     T* item;
-    Func invocation;
+    function_type invocation;
 
     template<typename... Args>
     functor(Args&&... args): item(nullptr), invocation(std::forward<Args>(args)...) {}
 
-    bool check () const {
-         return invocation != nullptr;
-    }
-
     template<typename... Args>
     void call(types<void>, Args&&... args) {
         T& member = *item;
-        (member.*invocation)(std::forward<Args>(args)...);
+        invocation(implicit_wrapper<T>(member), std::forward<Args>(args)...);
     }
 
     template<typename Ret, typename... Args>
     Ret call(types<Ret>, Args&&... args) {
         T& member = *item;
-        return (member.*invocation)(std::forward<Args>(args)...);
+        return invocation(implicit_wrapper<T>(member), std::forward<Args>(args)...);
+    }
+
+    template<typename... Args>
+    auto operator()(Args&&... args) -> decltype(std::declval<functor>().call(types<return_type>{}, std::forward<Args>(args)...)) {
+        return this->call(types<return_type>(), std::forward<Args>(args)...);
+    }
+};
+
+template<typename T, typename RSig, typename WSig, typename C>
+struct functor<T, member_property<RSig, WSig>, C> {
+    typedef meta::bind_traits<std::conditional_t<std::is_void<WSig>::value, RSig, WSig>> traits_type;
+    typedef meta::pop_front_type_t<typename traits_type::args_type> args_type;
+    typedef std::conditional_t<std::is_void<typename traits_type::return_type>::value, typename traits_type::template arg_at<0>, typename traits_type::return_type> return_type;
+    typedef member_property<RSig, WSig> function_type;
+    typedef meta::Not<std::is_void<RSig>> can_read;
+    typedef meta::Not<std::is_void<WSig>> can_write;
+    T* item;
+    function_type invocation;
+
+    template<typename... Args>
+    functor(Args&&... args): item(nullptr), invocation(std::forward<Args>(args)...) {}
+
+    template<typename Arg>
+    void call(Arg&& arg) {
+        T& member = *item;
+        invocation(member, std::forward<Arg>(arg));
+    }
+
+    decltype(auto) call() {
+        T& member = *item;
+        return invocation(member);
     }
 
     template<typename... Args>
     decltype(auto) operator()(Args&&... args) {
-        return this->call(types<return_type>{}, std::forward<Args>(args)...);
+        return this->call(std::forward<Args>(args)...);
     }
 };
 
@@ -86,16 +215,15 @@ struct functor<T, Func, std::enable_if_t<std::is_member_object_pointer<Func>::va
     typedef typename traits_type::args_type args_type;
     typedef typename traits_type::return_type return_type;
     static const std::size_t arity = traits_type::arity;
+    typedef std::true_type can_read;
+    typedef std::true_type can_write;
+
     T* item;
     Func invocation;
 
     template<typename... Args>
     functor(Args&&... args): item(nullptr), invocation(std::forward<Args>(args)...) {}
 
-    bool check () const {
-         return this->fx.invocation != nullptr;
-    }
-
     template<typename Arg>
     void call(Arg&& arg) {
         T& member = *item;
@@ -114,50 +242,33 @@ struct functor<T, Func, std::enable_if_t<std::is_member_object_pointer<Func>::va
 };
 
 template<typename T, typename Func>
-struct functor<T, Func, std::enable_if_t<std::is_function<Func>::value || std::is_class<Func>::value>> {
+struct functor<T, Func, std::enable_if_t<std::is_member_function_pointer<Func>::value>> {
     typedef meta::bind_traits<Func> traits_type;
-    typedef meta::pop_front_type_t<typename traits_type::args_type> args_type;
+    typedef typename traits_type::args_type args_type;
     typedef typename traits_type::return_type return_type;
     static const std::size_t arity = traits_type::arity;
-    typedef meta::tuple_element_t<0, typename traits_type::args_tuple_type> Arg0;
+
-    typedef std::conditional_t<std::is_pointer<Func>::value || std::is_class<Func>::value, Func, std::add_pointer_t<Func>> function_type;
-    static_assert(std::is_base_of<meta::Unqualified<std::remove_pointer_t<Arg0>>, T>::value, "Any non-member-function must have a first argument which is covariant with the desired userdata type.");
     T* item;
-    function_type invocation;
+    Func invocation;
-
-private:
-    bool check(std::false_type) const {
-        return true;
-    }
-
-    bool check(std::true_type) const {
-        return this->invocation != nullptr;
-    }
-
-public:
 
     template<typename... Args>
     functor(Args&&... args): item(nullptr), invocation(std::forward<Args>(args)...) {}
 
-    bool check () const {
-         return this->check(std::is_function<Func>());
-    }
-
     template<typename... Args>
     void call(types<void>, Args&&... args) {
         T& member = *item;
-        invocation(implicit_wrapper<T>(member), std::forward<Args>(args)...);
+        (member.*invocation)(std::forward<Args>(args)...);
     }
 
     template<typename Ret, typename... Args>
     Ret call(types<Ret>, Args&&... args) {
         T& member = *item;
-        return invocation(implicit_wrapper<T>(member), std::forward<Args>(args)...);
+        return (member.*invocation)(std::forward<Args>(args)...);
     }
 
     template<typename... Args>
-    auto operator()(Args&&... args) -> decltype(std::declval<functor>().call(types<return_type>{}, std::forward<Args>(args)...)) {
+    decltype(auto) operator()(Args&&... args) {
-        return this->call(types<return_type>(), std::forward<Args>(args)...);
+        return this->call(types<return_type>{}, std::forward<Args>(args)...);
     }
 };
 

sol/function_types_member.hpp

@@ -113,7 +113,7 @@ struct member_variable : public base_function {
 
     int set_assignable(std::false_type, lua_State* L, M) {
         lua_pop(L, 1);
-        return luaL_error(L, "cannot write to this type: copy assignment/constructor not available");
+        return luaL_error(L, "sol: cannot write to this type: copy assignment/constructor not available");
     }
 
     int set_assignable(std::true_type, lua_State* L, M mem) {
@@ -128,7 +128,7 @@ struct member_variable : public base_function {
 
     int set_variable(std::false_type, lua_State* L, M) {
         lua_pop(L, 1);
-        return luaL_error(L, "cannot write to a const variable");
+        return luaL_error(L, "sol: cannot write to a const variable");
     }
 
     int call(lua_State* L) {

sol/function_types_usertype.hpp

@@ -28,7 +28,7 @@
 
 namespace sol {
 namespace function_detail {
-template<typename Function, typename Tp>
+template<typename Tp, typename Function>
 struct usertype_function_core : public base_function {
     typedef std::remove_pointer_t<Tp> T;
     typedef std::remove_pointer_t<std::decay_t<Function>> function_type;
@@ -42,48 +42,15 @@ struct usertype_function_core : public base_function {
     template<typename... Args>
     usertype_function_core(Args&&... args): fx(std::forward<Args>(args)...) {}
 
-    template<typename Return, typename Raw = meta::Unqualified<Return>>
-    std::enable_if_t<std::is_same<T, Raw>::value, int> push(lua_State* L, Return&& r) {
-        if(detail::ptr(detail::unwrap(r)) == fx.item) {
-            // push nothing
-            // note that pushing nothing with the ':'
-            // syntax means we leave the instance of what
-            // was pushed onto the stack by lua to do the
-            // function call alone,
-            // and naturally lua returns that.
-            // It's an "easy" way to return *this,
-            // without allocating an extra userdata, apparently!
-            return 1;
-        }
-        return stack::push_reference(L, std::forward<Return>(r));
-    }
-
-    template<typename Return, typename Raw = meta::Unqualified<Return>>
-    std::enable_if_t<!std::is_same<T, Raw>::value, int> push(lua_State* L, Return&& r) {
-        return stack::push_reference(L, std::forward<Return>(r));
-    }
-
-    template<typename... Args, std::size_t Start>
-    int operator()(types<void> tr, types<Args...> ta, index_value<Start>, lua_State* L) {
-        stack::call_into_lua(tr, ta, L, static_cast<int>(Start), fx);
-        int nargs = static_cast<int>(sizeof...(Args));
-        lua_pop(L, nargs);
-        return 0;
-    }
-
     template<typename... Ret, typename... Args, std::size_t Start>
     int operator()(types<Ret...> tr, types<Args...> ta, index_value<Start>, lua_State* L) {
-        decltype(auto) r = stack::call(tr, ta, L, static_cast<int>(Start), fx);
+        return stack::call_into_lua<1>(tr, ta, L, static_cast<int>(Start), fx);
-        int nargs = static_cast<int>(sizeof...(Args));
-        lua_pop(L, nargs);
-        int pushcount = push(L, std::forward<decltype(r)>(r));
-        return pushcount;
     }
 };
 
-template<typename Function, typename Tp>
+template<typename Tp, typename Function>
-struct usertype_function : public usertype_function_core<Function, Tp> {
+struct usertype_function : public usertype_function_core<Tp, Function> {
-    typedef usertype_function_core<Function, Tp> base_t;
+    typedef usertype_function_core<Tp, Function> base_t;
     typedef std::remove_pointer_t<Tp> T;
     typedef typename base_t::traits_type traits_type;
     typedef typename base_t::args_type args_type;
@@ -102,41 +69,62 @@ struct usertype_function : public usertype_function_core<Function, Tp> {
     }
 };
 
-template<typename Function, typename Tp>
+template<typename Tp, typename Function>
-struct usertype_variable_function : public usertype_function_core<Function, Tp> {
+struct usertype_variable_function : public usertype_function_core<Tp, Function> {
-    typedef usertype_function_core<Function, Tp> base_t;
+    typedef usertype_function_core<Tp, Function> base_t;
     typedef std::remove_pointer_t<Tp> T;
+    typedef typename base_t::fx_t fx_t;
     typedef typename base_t::traits_type traits_type;
     typedef typename base_t::args_type args_type;
     typedef typename base_t::return_type return_type;
+    typedef typename fx_t::can_read can_read;
+    typedef typename fx_t::can_write can_write;
 
     template<typename... Args>
     usertype_variable_function(Args&&... args): base_t(std::forward<Args>(args)...) {}
 
     int set_assignable(std::false_type, lua_State* L) {
-        lua_pop(L, 2);
+        lua_pop(L, 3);
-        return luaL_error(L, "cannot write to this type: copy assignment/constructor not available");
+        return luaL_error(L, "sol: cannot write to this type: copy assignment/constructor not available");
     }
 
     int set_assignable(std::true_type, lua_State* L) {
+        return set_writable(can_write(), L);
+    }
+
+    int set_writable(std::false_type, lua_State* L) {
+        lua_pop(L, 3);
+        return luaL_error(L, "sol: cannot write to readonly variable");
+    }
+
+    int set_writable(std::true_type, lua_State* L) {
         return static_cast<base_t&>(*this)(meta::tuple_types<void>(), args_type(), index_value<3>(), L);
     }
 
     int set_variable(std::false_type, lua_State* L) {
-        lua_pop(L, 2);
+        lua_pop(L, 3);
-        return luaL_error(L, "cannot write to a const variable");
+        return luaL_error(L, "sol: cannot write to a const variable");
     }
 
     int set_variable(std::true_type, lua_State* L) {
         return set_assignable(std::is_assignable<std::add_lvalue_reference_t<return_type>, return_type>(), L);
     }
 
+    int get_variable(std::false_type, lua_State* L) {
+        lua_pop(L, 2);
+        return luaL_error(L, "sol: cannot read from a readonly property");
+    }
+
+    int get_variable(std::true_type, lua_State* L) {
+        return static_cast<base_t&>(*this)(meta::tuple_types<return_type>(), types<>(), index_value<2>(), L);
+    }
+
     int prelude(lua_State* L) {
         int argcount = lua_gettop(L);
         this->fx.item = stack::get<T*>(L, 1);
         switch(argcount) {
         case 2:
-            return static_cast<base_t&>(*this)(meta::tuple_types<return_type>(), types<>(), index_value<2>(), L);
+            return get_variable(can_read(), L);
         case 3:
             return set_variable(meta::Not<std::is_const<return_type>>(), L);
         default:

sol/object.hpp

@@ -25,6 +25,7 @@
 #include "reference.hpp"
 #include "userdata.hpp"
 #include "stack.hpp"
+#include "variadic_args.hpp"
 
 namespace sol {
 template <typename base_t>

sol/stack.hpp

@@ -69,14 +69,18 @@ inline std::pair<T, int> get_as_upvalues(lua_State* L, int index = 1) {
 
 template <bool checkargs = default_check_arguments, std::size_t... I, typename R, typename... Args, typename Fx, typename... FxArgs, typename = std::enable_if_t<!std::is_void<R>::value>>
 inline decltype(auto) call(types<R>, types<Args...> ta, std::index_sequence<I...> tai, lua_State* L, int start, Fx&& fx, FxArgs&&... args) {
+    typedef meta::index_in_pack<this_state, Args...> state_pack_index;
+    typedef std::integral_constant<int, state_pack_index::value == -1 ? std::numeric_limits<int>::max() : static_cast<int>(state_pack_index::value)> state_idx;
     check_types<checkargs>{}.check(ta, tai, L, start, type_panic);
-    return fx(std::forward<FxArgs>(args)..., stack_detail::unchecked_get<Args>(L, start + I)...);
+    return fx(std::forward<FxArgs>(args)..., stack_detail::unchecked_get<Args>(L, start + (state_idx::value < I ? I - 1 : I))...);
 }
 
 template <bool checkargs = default_check_arguments, std::size_t... I, typename... Args, typename Fx, typename... FxArgs>
 inline void call(types<void>, types<Args...> ta, std::index_sequence<I...> tai, lua_State* L, int start, Fx&& fx, FxArgs&&... args) {
+    typedef meta::index_in_pack<this_state, Args...> state_pack_index;
+    typedef std::integral_constant<int, state_pack_index::value == -1 ? std::numeric_limits<int>::max() : static_cast<int>(state_pack_index::value)> state_idx;
     check_types<checkargs>{}.check(ta, tai, L, start, type_panic);
-    fx(std::forward<FxArgs>(args)..., stack_detail::unchecked_get<Args>(L, start + I)...);
+    fx(std::forward<FxArgs>(args)..., stack_detail::unchecked_get<Args>(L, start + (state_idx::value < I ? I - 1 : I))...);
 }
 } // stack_detail
 
@@ -104,7 +108,7 @@ inline void remove( lua_State* L, int index, int count ) {
 
 template <bool check_args = stack_detail::default_check_arguments, typename R, typename... Args, typename Fx, typename... FxArgs, typename = std::enable_if_t<!std::is_void<R>::value>>
 inline decltype(auto) call(types<R> tr, types<Args...> ta, lua_State* L, int start, Fx&& fx, FxArgs&&... args) {
-    typedef typename types<Args...>::indices args_indices;
+    typedef std::make_index_sequence<sizeof...(Args)> args_indices;
     return stack_detail::call<check_args>(tr, ta, args_indices(), L, start, std::forward<Fx>(fx), std::forward<FxArgs>(args)...);
 }
 
@@ -115,7 +119,7 @@ inline decltype(auto) call(types<R> tr, types<Args...> ta, lua_State* L, Fx&& fx
 
 template <bool check_args = stack_detail::default_check_arguments, typename... Args, typename Fx, typename... FxArgs>
 inline void call(types<void> tr, types<Args...> ta, lua_State* L, int start, Fx&& fx, FxArgs&&... args) {
-    typedef typename types<Args...>::indices args_indices;
+    typedef std::make_index_sequence<sizeof...(Args)> args_indices;
     stack_detail::call<check_args>(tr, ta, args_indices(), L, start, std::forward<Fx>(fx), std::forward<FxArgs>(args)...);
 }
 
@@ -147,11 +151,11 @@ inline int call_into_lua(types<Ret0, Ret...>, types<Args...> ta, lua_State* L, i
     decltype(auto) r = call<check_args>(types<meta::return_type_t<Ret0, Ret...>>(), ta, L, start, std::forward<Fx>(fx), std::forward<FxArgs>(fxargs)...);
     int nargs = static_cast<int>(sizeof...(Args)) + additionalpop;
     lua_pop(L, nargs);
-    return push(L, std::forward<decltype(r)>(r));
+    return push_reference(L, std::forward<decltype(r)>(r));
 }
 
-inline call_syntax get_call_syntax(lua_State* L, const std::string& meta) {
+inline call_syntax get_call_syntax(lua_State* L, const std::string& key) {
-    luaL_getmetatable(L, meta.c_str());
+    luaL_getmetatable(L, key.c_str());
     if (lua_compare(L, -1, -2, LUA_OPEQ) == 1) {
         lua_pop(L, 1);
         return call_syntax::colon;

sol/stack_check.hpp

@@ -65,7 +65,7 @@ struct check_types {
     static bool check(types<Arg0, Args...>, std::index_sequence<I0, I...>, lua_State* L, int firstargument, Handler&& handler) {
         if (!stack::check<Arg0>(L, firstargument + I0, handler))
             return false;
-        return check(types<Args...>(), std::index_sequence<I...>(), L, firstargument, std::forward<Handler>(handler));
+        return check(types<Args...>(), std::index_sequence<I...>(), L, firstargument - static_cast<int>(std::is_same<this_state, meta::Unqualified<Arg0>>::value), std::forward<Handler>(handler));
     }
 
     template <typename Handler>
@@ -121,6 +121,22 @@ struct checker<nil_t, expected, C> {
 template <type expected, typename C>
 struct checker<nullopt_t, expected, C> : checker<nil_t> {};
 
+template <typename C>
+struct checker<this_state, type::none, C> {
+    template <typename Handler>
+    static bool check (lua_State*, int, Handler&&) {
+        return true;
+    }
+};
+
+template <typename C>
+struct checker<variadic_args, type::poly, C> {
+    template <typename Handler>
+    static bool check (lua_State*, int, Handler&&) {
+        return true;
+    }
+};
+
 template <typename T, typename C>
 struct checker<T, type::poly, C> {
     template <typename Handler>

sol/stack_get.hpp

@@ -63,26 +63,12 @@ struct getter<T, std::enable_if_t<meta::And<std::is_integral<T>, std::is_unsigne
 };
 
 template<typename T>
-struct getter<T, std::enable_if_t<std::is_base_of<reference, T>::value>> {
+struct getter<T, std::enable_if_t<std::is_base_of<reference, T>::value || std::is_base_of<stack_reference, T>::value>> {
     static T get(lua_State* L, int index = -1) {
         return T(L, index);
     }
 };
 
-template<typename T>
-struct getter<T, std::enable_if_t<std::is_base_of<stack_reference, T>::value>> {
-    static T get(lua_State* L, int index = -1) {
-        return T(L, index);
-    }
-};
-
-template<>
-struct getter<stack_reference> {
-    static stack_reference get(lua_State* L, int index = -1) {
-        return stack_reference(L, index);
-    }
-};
-
 template<>
 struct getter<userdata_value> {
     static userdata_value get(lua_State* L, int index = -1) {
@@ -148,6 +134,13 @@ struct getter<nullopt_t> {
     }
 };
 
+template<>
+struct getter<this_state> {
+    static this_state get(lua_State* L, int = -1) {
+        return this_state{L};
+    }
+};
+
 template<>
 struct getter<lua_CFunction> {
     static lua_CFunction get(lua_State* L,  int index = -1) {

sol/stack_proxy.hpp

@@ -39,9 +39,30 @@ public:
         return stack::get<T>(L, stack_index());
     }
 
+    int push () const {
+        lua_pushvalue(L, index);
+        return 1;
+    }
+
     lua_State* lua_state() const { return L; }
     int stack_index() const { return index; }
 };
+
+namespace stack {
+template <>
+struct getter<stack_proxy> {
+    static stack_proxy get(lua_State* L, int index = -1) {
+        return stack_proxy(L, index);
+    }
+};
+
+template <>
+struct pusher<stack_proxy> {
+    static int push(lua_State*, const stack_proxy& ref) {
+        return ref.push();
+    }
+};
+} // stack
 } // sol
 
 #endif // SOL_STACK_PROXY_HPP

sol/stack_push.hpp

@@ -175,7 +175,7 @@ struct pusher<T, std::enable_if_t<meta::And<meta::has_begin_end<T>, meta::has_ke
 };
 
 template<typename T>
-struct pusher<T, std::enable_if_t<std::is_base_of<reference, T>::value>> {
+struct pusher<T, std::enable_if_t<std::is_base_of<reference, T>::value || std::is_base_of<stack_reference, T>::value>> {
     static int push(lua_State*, T& ref) {
         return ref.push();
     }
@@ -185,13 +185,6 @@ struct pusher<T, std::enable_if_t<std::is_base_of<reference, T>::value>> {
     }
 };
 
-template<>
-struct pusher<stack_reference> {
-    static int push(lua_State*, const stack_reference& ref) {
-        return ref.push();
-    }
-};
-
 template<>
 struct pusher<bool> {
     static int push(lua_State* L, bool b) {
@@ -333,6 +326,13 @@ struct pusher<nullopt_t> {
         return stack::push(L, nil);
     }
 };
+
+template<>
+struct pusher<this_state> {
+    static int push(lua_State*, const this_state&) {
+        return 0;
+    }
+};
 } // stack
 } // sol
 

sol/traits.hpp

@@ -132,6 +132,17 @@ struct find_in_pack_v : Bool<false> { };
 template<typename V, typename Vs1, typename... Vs>
 struct find_in_pack_v<V, Vs1, Vs...> : Or<Bool<(V::value == Vs1::value)>, find_in_pack_v<V, Vs...>> { };
 
+namespace meta_detail {
+    template<std::size_t I, typename T, typename... Args>
+    struct index_in_pack : std::integral_constant<std::ptrdiff_t, -1> { };
+
+    template<std::size_t I, typename T, typename T1, typename... Args>
+    struct index_in_pack<I, T, T1, Args...> : std::conditional_t<std::is_same<T, T1>::value, std::integral_constant<std::ptrdiff_t, I>, index_in_pack<I + 1, T, Args...>> { };
+}
+
+template<typename T, typename... Args>
+struct index_in_pack : meta_detail::index_in_pack<0, T, Args...> { };
+
 template<std::size_t I, typename... Args>
 struct at_in_pack {};
 

sol/types.hpp

@@ -83,7 +83,8 @@ inline int c_trampoline(lua_State* L, lua_CFunction f) {
     return trampoline(L, f);
 }
 #endif // Exceptions vs. No Exceptions
-}
+struct empty { void operator()() {} };
+} // detail
 struct nil_t {};
 const nil_t nil {};
 struct metatable_key_t {};
@@ -91,7 +92,7 @@ const metatable_key_t metatable_key = {};
 inline bool operator==(nil_t, nil_t) { return true; }
 inline bool operator!=(nil_t, nil_t) { return false; }
 
-typedef std::add_lvalue_reference_t<std::remove_pointer_t<lua_CFunction>> lua_r_CFunction;
+typedef std::remove_pointer_t<lua_CFunction> lua_r_CFunction;
 
 template <typename T, typename = void>
 struct unique_usertype {};
@@ -132,6 +133,16 @@ struct c_closure {
     c_closure(lua_CFunction f, int upvalues = 0) : c_function(f), upvalues(upvalues) {}
 };
 
+struct this_state {
+    lua_State* L;
+    operator lua_State* () const {
+        return L;
+    }
+    lua_State* operator-> () const {
+        return L;
+    }
+};
+
 enum class call_syntax {
     dot = 0,
     colon = 1
@@ -295,6 +306,7 @@ template <typename base_t>
 class basic_userdata;
 template <typename base_t>
 class basic_lightuserdata;
+struct variadic_args;
 using object = basic_object<reference>;
 using stack_object = basic_object<stack_reference>;
 using userdata = basic_userdata<reference>;
@@ -377,7 +389,10 @@ template <typename Signature>
 struct lua_type_of<std::function<Signature>> : std::integral_constant<type, type::function>{};
 
 template <typename T>
-struct lua_type_of<optional<T>> : std::integral_constant<type, type::poly>{};
+struct lua_type_of<optional<T>> : std::integral_constant<type, type::poly> {};
+
+template <>
+struct lua_type_of<variadic_args> : std::integral_constant<type, type::poly> {};
 
 template <typename T>
 struct lua_type_of<T*> : std::integral_constant<type, type::userdata> {};
@@ -388,6 +403,9 @@ struct lua_type_of<T, std::enable_if_t<std::is_arithmetic<T>::value>> : std::int
 template <typename T>
 struct lua_type_of<T, std::enable_if_t<std::is_enum<T>::value>> : std::integral_constant<type, type::number> {};
 
+template <>
+struct lua_type_of<this_state> : std::integral_constant<type, type::none> {};
+
 template <typename T>
 struct is_lua_primitive : std::integral_constant<bool, 
     type::userdata != lua_type_of<meta::Unqualified<T>>::value

sol/usertype.hpp

@@ -197,10 +197,15 @@ private:
         return std::make_unique<function_detail::usertype_constructor_function<T, Functions...>>(std::move(func.set));
     }
 
+    template<typename RSig, typename WSig>
+    std::unique_ptr<function_detail::base_function> make_function(const std::string&, member_property<RSig, WSig> func) {
+        return std::make_unique<function_detail::usertype_variable_function<T, member_property<RSig, WSig>>>(std::move(func));
+    }
+
     template<typename Fx>
     std::unique_ptr<function_detail::base_function> make_free_function(std::true_type, const std::string&, Fx&& func) {
         typedef std::decay_t<meta::Unqualified<Fx>> function_type;
-        return std::make_unique<function_detail::usertype_function<function_type, T>>(func);        
+        return std::make_unique<function_detail::usertype_function<T, function_type>>(func);
     }
 
     template<typename Fx>
@@ -219,16 +224,16 @@ private:
 
     template<typename Base, typename Ret>
     std::unique_ptr<function_detail::base_function> make_variable_function(std::true_type, const std::string&, Ret Base::* func) {
-        static_assert(std::is_base_of<Base, T>::value, "Any registered function must be part of the class");
+        static_assert(std::is_base_of<Base, T>::value, "Any registered member variable must be part of the class");
         typedef std::decay_t<decltype(func)> function_type;
-        return std::make_unique<function_detail::usertype_variable_function<function_type, T>>(func);
+        return std::make_unique<function_detail::usertype_variable_function<T, function_type>>(func);
     }
 
     template<typename Base, typename Ret>
     std::unique_ptr<function_detail::base_function> make_variable_function(std::false_type, const std::string&, Ret Base::* func) {
-        static_assert(std::is_base_of<Base, T>::value, "Any registered function must be part of the class");
+        static_assert(std::is_base_of<Base, T>::value, "Any registered member function must be part of the class");
         typedef std::decay_t<decltype(func)> function_type;
-        return std::make_unique<function_detail::usertype_function<function_type, T>>(func);
+        return std::make_unique<function_detail::usertype_function<T, function_type>>(func);
     }
 
     template<typename Base, typename Ret>
@@ -240,7 +245,7 @@ private:
     template<typename Fx>
     std::unique_ptr<function_detail::base_function> make_functor_function(std::true_type, const std::string&, Fx&& func) {
         typedef std::decay_t<meta::Unqualified<Fx>> function_type;
-        return std::make_unique<function_detail::usertype_function<function_type, T>>(func);        
+        return std::make_unique<function_detail::usertype_function<T, function_type>>(func);
     }
 
     template<typename Fx>
@@ -339,7 +344,7 @@ private:
 
     template<std::size_t N, typename Fx>
     void build_function(std::string funcname, Fx&& func) {
-        typedef std::is_member_object_pointer<meta::Unqualified<Fx>> is_variable;
+        typedef meta::Or<std::is_member_object_pointer<meta::Unqualified<Fx>>, meta::is_specialization_of<member_property, meta::Unqualified<Fx>>> is_variable;
         functionnames.push_back(std::move(funcname));
         std::string& name = functionnames.back();
         auto baseptr = make_function(name, std::forward<Fx>(func));

sol/variadic_args.hpp

@@ -0,0 +1,102 @@
+// The MIT License (MIT) 
+
+// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef SOL_VARIADIC_ARGS_HPP
+#define SOL_VARIADIC_ARGS_HPP
+
+#include "stack.hpp"
+#include "stack_proxy.hpp"
+
+namespace sol {
+struct variadic_args {
+private:
+    lua_State* L;
+    int index;
+    int stacktop;
+
+public:
+    variadic_args() = default;
+    variadic_args(lua_State* L, int index = -1): L(L), index(lua_absindex(L, index)), stacktop(lua_gettop(L)) {}
+    variadic_args(const variadic_args&) = default;
+    variadic_args& operator=(const variadic_args&) = default;
+    variadic_args(variadic_args&& o) : L(o.L), index(o.index), stacktop(o.stacktop) {
+        // Must be manual, otherwise destructor will screw us
+        // return count being 0 is enough to keep things clean
+        // but will be thorough
+        o.L = nullptr;
+        o.index = 0;
+        o.stacktop = 0;
+    }
+    variadic_args& operator=(variadic_args&& o) {
+        L = o.L;
+        index = o.index;
+        stacktop = o.stacktop;
+        // Must be manual, otherwise destructor will screw us
+        // return count being 0 is enough to keep things clean
+        // but will be thorough
+        o.L = nullptr;
+        o.index = 0;
+        o.stacktop = 0;
+        return *this;
+    }
+
+    int push () const {
+        int pushcount = 0;
+        for (int i = index; i <= stacktop; ++i) {
+            lua_pushvalue(L, i);
+            pushcount += 1;
+        }
+        return pushcount;
+    }
+
+    template<typename T>
+    decltype(auto) get(int start = 0) const {
+        return stack::get<T>(L, index + start);
+    }
+
+    stack_proxy operator[](int start) const {
+        return stack_proxy(L, index + start);
+    }
+
+    lua_State* lua_state() const { return L; };
+    int stack_index() const { return index; };
+    int leftover_count() const { return stacktop - (index - 1); }
+    int top() const { return stacktop; }
+};
+
+namespace stack {
+template <>
+struct getter<variadic_args> {
+    static variadic_args get(lua_State* L, int index = -1) {
+        return variadic_args(L, index);
+    }
+};
+
+template <>
+struct pusher<variadic_args> {
+    static int push(lua_State*, const variadic_args& ref) {
+        return ref.push();
+    }
+};
+} // stack
+} // sol
+
+#endif // SOL_VARIADIC_ARGS_HPP

test_functions.cpp

@@ -443,11 +443,11 @@ TEST_CASE("functions/all-kinds", "Register all kinds of functions, make sure the
     };
 
     struct inner {
-	    const int z = 5653;
+        const int z = 5653;
     };
 
     struct nested {
-	    inner i;
+        inner i;
     };
 
     auto a = []() { return 500; };
@@ -749,3 +749,35 @@ end)");
     REQUIRE(b == 2);
     REQUIRE(c == 3);
 }
+
+TEST_CASE("functions/variadic_args", "Check to see we can receive multiple arguments through a variadic") {
+    struct structure {
+        int x;
+        bool b;
+    };
+
+    sol::state lua;
+    lua.open_libraries(sol::lib::base);
+    lua.set_function("v", [](sol::this_state, sol::variadic_args va) -> structure {
+        int r = 0;
+        for (int i = 0; i < va.leftover_count(); ++i) {
+            int v = va[i];
+            r += v;
+        }
+        return{ r, r > 200 };
+    });
+    
+    lua.script("x = v(25, 25)");
+    lua.script("x2 = v(25, 25, 100, 50, 250, 150)");
+    lua.script("x3 = v(1, 2, 3, 4, 5, 6)");
+
+    structure& lx = lua["x"];
+    structure& lx2 = lua["x2"];
+    structure& lx3 = lua["x3"];
+    REQUIRE(lx.x == 50);
+    REQUIRE(lx2.x == 600);
+    REQUIRE(lx3.x == 21);
+    REQUIRE_FALSE(lx.b);
+    REQUIRE(lx2.b);
+    REQUIRE_FALSE(lx3.b);
+}

test_stack_guard.hpp

@@ -1,11 +1,11 @@
 #pragma once
 
-struct stack_guard {
+struct test_stack_guard {
     lua_State* L;
     int& begintop;
     int& endtop;
-    stack_guard(lua_State* L, int& begintop, int& endtop) : L(L), begintop(begintop), endtop(endtop) { 
+    test_stack_guard(lua_State* L, int& begintop, int& endtop) : L(L), begintop(begintop), endtop(endtop) { 
         begintop = lua_gettop(L);
     }
-    ~stack_guard() { endtop = lua_gettop(L); }
+    ~test_stack_guard() { endtop = lua_gettop(L); }
 };

test_tables.cpp

@@ -168,7 +168,7 @@ TEST_CASE("tables/iterators", "Testing the use of iteratrs to get values from a
     int begintop = 0;
     int endtop = 0;
     {
-        stack_guard s(lua.lua_state(), begintop, endtop);
+        test_stack_guard s(lua.lua_state(), begintop, endtop);
         for (auto& kvp : tbl) {
             [&iterations](sol::object key, sol::object value) {
             ++iterations;

tests.cpp

@@ -192,39 +192,39 @@ TEST_CASE("table/traversal", "ensure that we can chain requests and tunnel down
 
     lua.script("t1 = {t2 = {t3 = 24}};");
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         int traversex24 = lua.traverse_get<int>("t1", "t2", "t3");
         REQUIRE(traversex24 == 24);
     } REQUIRE(begintop == endtop);
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         int x24 = lua["t1"]["t2"]["t3"];
         REQUIRE(x24 == 24);
     } REQUIRE(begintop == endtop);
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         lua["t1"]["t2"]["t3"] = 64;
         int traversex64 = lua.traverse_get<int>("t1", "t2", "t3");
         REQUIRE(traversex64 == 64);
     } REQUIRE(begintop == endtop);
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         int x64 = lua["t1"]["t2"]["t3"];
         REQUIRE(x64 == 64);
     } REQUIRE(begintop == endtop);
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         lua.traverse_set("t1", "t2", "t3", 13);
         int traversex13 = lua.traverse_get<int>("t1", "t2", "t3");
         REQUIRE(traversex13 == 13);
     } REQUIRE(begintop == endtop);
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         int x13 = lua["t1"]["t2"]["t3"];
         REQUIRE(x13 == 13);
     } REQUIRE(begintop == endtop);
@@ -234,18 +234,18 @@ TEST_CASE("simple/set", "Check if the set works properly.") {
     sol::state lua;
     int begintop = 0, endtop = 0;
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         lua.set("a", 9);
     } REQUIRE(begintop == endtop);
     REQUIRE_NOTHROW(lua.script("if a ~= 9 then error('wrong value') end"));
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         lua.set("d", "hello");
     } REQUIRE(begintop == endtop);
     REQUIRE_NOTHROW(lua.script("if d ~= 'hello' then error('expected \\'hello\\', got '.. tostring(d)) end"));
 
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         lua.set("e", std::string("hello"), "f", true);
     } REQUIRE(begintop == endtop);
     REQUIRE_NOTHROW(lua.script("if d ~= 'hello' then error('expected \\'hello\\', got '.. tostring(d)) end"));
@@ -258,21 +258,21 @@ TEST_CASE("simple/get", "Tests if the get function works properly.") {
 
     lua.script("a = 9");
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         auto a = lua.get<int>("a");
         REQUIRE(a == 9.0);
     } REQUIRE(begintop == endtop);
 
     lua.script("b = nil");
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         REQUIRE_NOTHROW(lua.get<sol::nil_t>("b"));
     } REQUIRE(begintop == endtop);
 
     lua.script("d = 'hello'");
     lua.script("e = true");
     {
-        stack_guard g(lua.lua_state(), begintop, endtop);
+        test_stack_guard g(lua.lua_state(), begintop, endtop);
         std::string d;
         bool e;
         std::tie( d, e ) = lua.get<std::string, bool>("d", "e");
@@ -944,3 +944,91 @@ lw2 = bark.something2(2, 3)
 
     REQUIRE_THROWS(lua.script("b.var2 = 2"));
 }
+
+TEST_CASE("usertype/properties", "Check if member properties/variables work") {
+    struct bark {
+        int var = 50;
+        int var2 = 25;
+
+        int get_var2() const {
+            return var2;
+        }
+
+        int get_var3() {
+            return var2;
+        }
+
+        void set_var2( int x ) {
+            var2 = x;
+        }
+    };
+
+    sol::state lua;
+    lua.open_libraries(sol::lib::base);
+    lua.new_usertype<bark>("bark",
+        "var", &bark::var,
+        "var2", sol::readonly( &bark::var2 ),
+        "a", sol::property(&bark::get_var2, &bark::set_var2),
+        "b", sol::property(&bark::get_var2),
+        "c", sol::property(&bark::get_var3),
+        "d", sol::property(&bark::set_var2)
+    );
+
+    bark b;
+    lua.set("b", &b);
+
+    lua.script("b.a = 59");
+    lua.script("var2_0 = b.a");
+    lua.script("var2_1 = b.b");
+    lua.script("b.d = 1568");
+    lua.script("var2_2 = b.c");
+
+    int var2_0 = lua["var2_0"];
+    int var2_1 = lua["var2_1"];
+    int var2_2 = lua["var2_2"];
+    REQUIRE(var2_0 == 59);
+    REQUIRE(var2_1 == 59);
+    REQUIRE(var2_2 == 1568);
+
+    REQUIRE_THROWS(lua.script("b.var2 = 24"));
+    REQUIRE_THROWS(lua.script("r = b.d"));
+    REQUIRE_THROWS(lua.script("r = b.d"));
+    REQUIRE_THROWS(lua.script("b.b = 25"));
+    REQUIRE_THROWS(lua.script("b.c = 11"));
+}
+
+TEST_CASE("utilities/this_state", "Ensure this_state argument can be gotten anywhere in the function.") {
+    struct bark {
+        int with_state(sol::this_state l, int a, int b) {
+            lua_State* L = l;
+            int c = lua_gettop(L);
+            return a + b + (c - c);
+        }
+
+        static int with_state_2(int a, sol::this_state l, int b) {
+            lua_State* L = l;
+            int c = lua_gettop(L);
+            return a * b + (c - c);
+        }
+    };
+
+    sol::state lua;
+    lua.open_libraries(sol::lib::base);
+    lua.new_usertype<bark>("bark",
+        "with_state", &bark::with_state
+    );
+
+    bark b;
+    lua.set("b", &b);
+    lua.set("with_state_2", bark::with_state_2);
+    sol::function fx = lua["with_state_2"];
+    int a = fx(25, 25);
+    lua.script("a = with_state_2(25, 25)");
+    lua.script("c = b:with_state(25, 25)");
+    int la = lua["a"];
+    int lc = lua["c"];
+
+    REQUIRE(lc == 50);
+    REQUIRE(a == 625);
+    REQUIRE(la == 625);
+}