luax_extendtype; luax_checktypeof;

src/luax.c

@@ -71,6 +71,16 @@ void luax_registertype(lua_State* L, const char* name, const luaL_Reg* functions
   lua_pop(L, 1);
 }
 
+void luax_extendtype(lua_State* L, const char* base, const char* name, const luaL_Reg* functions) {
+  luax_registertype(L, name, functions);
+  luaL_getmetatable(L, name);
+
+  lua_pushstring(L, base);
+  lua_setfield(L, -2, "super");
+
+  lua_pop(L, 1);
+}
+
 int luax_releasetype(lua_State* L) {
   lovrRelease(*(Ref**) lua_touserdata(L, 1));
   return 0;

src/luax.h

@@ -5,7 +5,17 @@
 
 #pragma once
 
+#define STRINGIFY(x) #x
+
 #define luax_checktype(L, i, T) *(T**) luaL_checkudata(L, i, #T)
+#define luax_checktypeof(L, i, T) \
+  *(T**) (luaL_argcheck(L, lua_touserdata(L, i), i, "Expected " STRINGIFY(T)), \
+  lua_getmetatable(L, i), \
+  lua_getfield(L, -1, "super"), \
+  lua_pushstring(L, #T), \
+  luaL_argcheck(L, lua_equal(L, -1, -2), i, "Expected " STRINGIFY(T)), \
+  lua_pop(L, 3), \
+  lua_touserdata(L, i))
 #define luax_newobject(L, T, x) \
   T** u = (T**) lua_newuserdata(L, sizeof(T**)); \
   luax_registerobject(L, x); \
@@ -16,6 +26,7 @@
 
 int luax_preloadmodule(lua_State* L, const char* key, lua_CFunction f);
 void luax_registertype(lua_State* L, const char* name, const luaL_Reg* functions);
+void luax_extendtype(lua_State* L, const char* base, const char* name, const luaL_Reg* functions);
 int luax_releasetype(lua_State* L);
 int luax_getobject(lua_State* L, void* object);
 void luax_registerobject(lua_State* L, void* object);