settled on simple forwarding functionality for full userdata

go-style helpers as well as go type wrappers destined for separate lib

example/Makefile

@@ -1,7 +1,7 @@
 
 include $(GOROOT)/src/Make.$(GOARCH)
 
-all: basic panic
+all: basic panic userdata
 
 basic: basic.8
 	$(LD) -o basic basic.8
@@ -15,5 +15,11 @@ panic: panic.8
 panic.8: panic.go
 	$(GC) -o panic.8 panic.go
 
+userdata: userdata.8
+	$(LD) -o userdata userdata.8
+
+userdata.8: userdata.go
+	$(GC) -o userdata.8 userdata.go
+
 clean:
 	-rm -f basic panic *.8

example/userdata.go

@@ -0,0 +1,28 @@
+package main
+
+import lua "lua51"
+import "unsafe"
+import "fmt"
+
+type Userdata struct {
+	a,b int
+}
+
+func main() {
+	var L *lua.State;
+	L = lua.NewState();
+	lua.OpenLibs(L);
+
+	rawptr := lua.NewUserdata(L,uintptr(unsafe.Sizeof(Userdata{})));
+	var ptr *Userdata;
+	ptr = (*Userdata)(rawptr);
+	ptr.a = 2;
+	ptr.b = 3;
+
+	fmt.Println(ptr);
+
+	rawptr2 := lua.ToUserdata(L,-1);
+	ptr2 := (*Userdata)(rawptr2);
+
+	fmt.Println(ptr2);
+}

lua51/lua.go

@@ -145,8 +145,8 @@ func PushUserdata(L *State, ud interface{}) {
 
 //TODO:
 //old style
-func NewUserdata(L* State, size uintptr) uintptr {
-	return 0;
+func NewUserdata(L* State, size uintptr) unsafe.Pointer {
+	return unsafe.Pointer(C.lua_newuserdata(L.s, C.size_t(size)));
 }
 
 
@@ -235,7 +235,7 @@ func IsBoolean(L *State, index int) bool {
 }
 
 func IsGoFunction(L *State, index int) bool {
-	//TODO: add a check if c function to distinguish c function from go function
+	//TODO:go function is now a userdatum, not a c function, so this will not work 
 	return C.lua_iscfunction(L.s, C.int(index)) == 1
 }
 
@@ -290,6 +290,7 @@ func NewTable(L *State) {
 	C.lua_createtable(L.s,0,0);
 }
 
+
 func NewThread(L* State) *State {
 	//TODO: call newState with result from C.lua_newthread and return it
 	//TODO: 
@@ -449,9 +450,8 @@ func ToThread(L *State, index int) *State {
 	return &State{}
 }
 
-func ToUserdata(L *State, index int) interface{} {
-	//TODO: needs userdata implementation first...
-	return 0;
+func ToUserdata(L *State, index int) unsafe.Pointer {
+	return unsafe.Pointer(C.lua_touserdata(L.s,C.int(index)));
 }
 
 func Type(L *State, index int) int {