Speichern Bezug auf Lua Benutzerdaten

Question

# 1 Lua:

local test = Test();

# 2 C:

//creating "lua's test"
luaL_newmetatable(L, "someTable");
lua_userdata *userData = (lua_userdata *)lua_newuserdata(L, sizeof(lua_userdata));

luaL_getmetatable(L, "someTable");
lua_setmetatable(L, -2);

# 3 Lua:

function test.newMethod()
end

# 4 C:

//this part is not executed from Lua
//what i have to have here from #2 to call "test.newMethod" and how to call it?
//if userdata would be on stack i guess i could:
luaL_getmetafield (L, 1, "newMethod");
lua_call(L, 0, 0);
//but because this part is not executed by Lua call its not on stack.

Editiert:

wird versuchen, einfacher zu erklären, in Pseudo-Code:

Lua:

local test = Object(); 

C:

int Object(){ 
    ... 
    somePointer = luaL_newmetatable(...); //how to get this "somePointer"? maybe luaL_ref?
    push ... 
} 

Lua: macht neue Methode

function test.newMethod() 
    ... 
end 

C ein Ereignis (können sagen, Timer) löst C Methode

void triggeredCMethod(){ 
    //here i need to call test.newMethod 
    //if i would have here 'somePointer' and could push it to Lua stack i could find and call newMethod 
}

so Frage ist: Wie in C speichern Zeiger auf ein Lua-Objekt (hoffe ich brauche, dass), erhalten Lua Objekt durch diesen Zeiger und Call-Methode darin

Answer 1

Ich nehme an, Sie dynamisch hinzugefügt Funktionen aufrufen können, wollen. Dieser Code sollte es relativ einfach erklären. Hinweis ich nicht viel tun, Fehlerprüfung und einige Annahmen getroffen werden, kopieren Sie nicht diese Paste als eine Lösung.

typedef struct
{
    int number;
    int reference;
    lua_State *L;
} TestUserdata;

static int m_newindex( lua_State *L )
{
    /* This is passed three values, first ( at -3 ) is the object, bring this to the front */
    lua_getfenv( L, -3 );
    /* Now bring the second arg forward, the key */
    lua_pushvalue( L, -3 );
    /* And the third arg, the value */
    lua_pushvalue( L, -3 );
    /* And we're done */
    lua_rawset( L, -3 );

    return 0;
}

static int m_tostring( lua_State *L )
{
    lua_pushstring( L, "TestUserdata" );
    return 1;
}

static int callobject( lua_State *L )
{
    /* Grab the object passed, check it's the right type */
    TestUserdata *data = luaL_checkudata( L, 1, "TestUserdata" );

    /* Grab the function environment we gave it in createobject, and look in there for newmethod */
    lua_getfenv( L, -1 );
    lua_pushstring( L, "newmethod" );
    lua_rawget( L, -2 );

    /* Call the function */
    lua_pushinteger( L, data->number );
    lua_call( L, 1, 0 );

    return 0;
}

static const struct luaL_reg userdata_m[] = {
    { "__newindex", m_newindex },
    { "__tostring", m_tostring },
    { NULL, NULL }
};

int main (int argc, char *argv[])
{
    lua_State *L = luaL_newstate();
    luaL_openlibs( L );

    /* Let's create us a userdatum metatable, and fill it up with goodies */
    luaL_newmetatable( L, "TestUserdata" );
    /* Use luaL_register to fill up the metatable for us */
    luaL_register( L, NULL, userdata_m );
    lua_pop( L, 1 ); /* Clean up the stack, we won't need the metatable left here */

    TestUserdata *data = lua_newuserdata( L, sizeof( TestUserdata ) );
    lua_pushvalue( L, -1 ); /* Copy for luaL_ref */
    int ref = luaL_ref( L, LUA_REGISTRYINDEX );
    data->reference = ref;
    data->number = 42;
    data->L = L;

    /* Load the metatable from before and 'give' it to this userdatum */
    luaL_getmetatable( L, "TestUserdata" );
    lua_setmetatable( L, -2 );

    /* Give this object an empty function environment */
    lua_newtable( L );
    lua_setfenv( L, -2 );

    lua_setglobal( L, "test" );

    luaL_dostring( L, "function test.newmethod( num ) print( num ) end" );

    /* Now provided we have the object, we can call any method defined anywhere */
    lua_rawgeti( data->L, LUA_REGISTRYINDEX, data->reference );
    lua_getfenv( data->L, -1 );
    lua_pushstring( data->L, "newmethod" );
    lua_rawget( data->L, -2 );
    lua_remove( data->L, -2 );

    if( lua_isfunction( data->L, -1 ) == 1 )
    {
        lua_pushinteger( data->L, data->number );

        lua_pcall( data->L, 1, 0, 0 );
    }

    lua_close( L );

    return 0;
}

Überprüfen Sie, dass ich denke, das ist, was Sie nach.

Answer 2

Wenn alles, was Sie wollen, ist die Lua-Funktion `test.newMethod ()‘ nennen, dann denke ich Sie etwas in der Größenordnung von dieser wollen:

lua_getglobal(L, "test");
lua_getfield(L, -1, "newMethod");
lua_call(L, 0, 0);

Ich glaube nicht, Sie verwirren mit einem Metatabelle oder Benutzerdaten benötigen.

Doch die Kraft Ihrer Frage ist mir nicht ganz klar ...