How to return a table of tables to Lua from C/C++ function, through a for loop

Question

I have a std::list of objects, and I want to give Lua a function that returns its 2D positions. So I need to create a table of tables

{ {x,y}, {x,y}, {x,y}...}

And since its all on a list, I need to create it while iterating the list..

    lua_newtable(L_p);  // table at 0
    int tableIndex = 1; // first entry at 1

    for(    std::list<AmmoDropped*>::iterator it = m_inputAmmosDropped.begin();
            it != m_inputAmmosDropped.end();
            ++it ){

        // what do I do here

        ++tableIndex;
    }

    // returns the table
    return 1;

Indexed by integer keys, and by 'x' and 'y':

 positions[0].x
 positions[0].y

Id try by trial and error, but since I don't know / don't have how debug it for now, I'm really lost.

related to stackoverflow.com/questions/453769/…

Dmitry Ledentsov
– Dmitry Ledentsov

2012-11-10 21:32:42 +00:00
Commented Nov 10, 2012 at 21:32 — Dmitry Ledentsov
– Dmitry Ledentsov, Commented Nov 10, 2012 at 21:32
See also my library github.com/prapin/LuaClassBasedCall

prapin
– prapin

2012-11-10 23:50:08 +00:00
Commented Nov 10, 2012 at 23:50 — prapin
– prapin, Commented Nov 10, 2012 at 23:50

Gilles Gregoire · Accepted Answer · 2012-11-11 00:15:02Z

1

It will go like this:

lua_newtable(L);    // table at 0
int tableIndex = 1; // first entry at 1

for(std::list<AmmoDropped*>::iterator it = m_inputAmmosDropped.begin();
      it != m_inputAmmosDropped.end();
      ++it ){
    lua_createtable(L, 2, 0);  // a 2 elements subtable
    lua_pushnumber(L, it->x);
    lua_rawseti(L, -2, 1);     // x is element 1 of subtable
    lua_pushnumber(L, it->y);
    lua_rawseti(L, -2, 2);     // y is element 2 of subtable
    lua_rawseti(L, -3, tableIndex++)    // table {x,y} is element tableIndex
}
return 1;

warning: this is untested code from the top of my head...

answered Nov 11, 2012 at 0:15

Gilles Gregoire

1,7761 gold badge12 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to return a table of tables to Lua from C/C++ function, through a for loop

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related