Calling C++ from Lua

To call C++ code from Lua, the C++ code needs to be exported via a lua_CFunction implementation, which is defined as follows:

typedef int (*lua_CFunction) (lua_State *L);

For example, in LuaExecutor, we implemented a function:

int luaGetExecutorVersionCode(lua_State *L)
{
   lua_pushinteger(L, LuaExecutor::versionCode);
   return 1;
}

This returns a single integer value to the Lua code. A simple way to export this function to the global table can be implemented as follows:

void registerHostFunctions(lua_State *L)
{
    lua_pushcfunction(L, luaGetExecutorVersionCode);
    lua_setglobal(L, "host_version");
}

You can use lua_pushcfunction to push lua_CFunction onto the stack and then assign it to a variable of your choice.

However, more than likely, you should export a group of functions as a module.

Exporting C++ modules

To export a C++ module, you simply need...