Simple Lua Icxx Example

wiki

• you no longer need to worry about stack indices/cleanup
• Lua objects and results are naturally expressed via classes like LuaFuncRef? and LuaTableRef?
• there is considerably less code to write, and fewer opportunities for mistakes
• code is more expressive, easier to understand intent

/*

 * The lua-icxx (C++) equivalent of API example at 

 * http://lua-users.org/wiki/SimpleLuaApiExample.

 * Oliver Schoenborn, Jul 2011

 */



#include "lua_icxx/lua_icxx.h"

#include "iof/fmtr.hpp"



#include <iostream>



int

main()

{

    LuaInterpreter L;



    /* Load the file containing the script we are going to run */

    LuaFuncRef chunk = L.chunkFromFile("sample1.lua");

    if ( chunk.isError() ) {

        std::cerr << "Couldn't load file: " << chunk.getErrMsg() << std::endl;

        exit(1);

    }



    LuaTableRef table = L.newTable();

    for (int i = 1; i <= 5; i++)

        table[i] = i*2;



    /* By what name is the script going to reference our table? */

    L.setGlobal("foo", table);



    /* Ask Lua to run our little script */

    LuaTempResult res = chunk();

    if ( res.isError() ) {

        std::cerr << "Failed to run script: " << res.getErrMsg() << std::endl;

        exit(1);

    }



    /* Get the returned value at the top of the stack (index -1) */

    double sum = res[1]; 



    // following line uses the iof library (ioflib.sf.net) for printf-output in c++

    std::cout << iof::fmtr("Script returned: %.0fs") << sum << std::endl;



    return 0;

}

In version 1.x, lua-icxx only supports part of the Lua C API, but the C API can be used in conjunction with lua-icxx. Extending lua-icxx to cover more of the C API is easy to do, email author (schoenborno@users.sf.net).

If you wonder why lua-icxx does not provide ways to bind to C++ code from Lua, it is because this can be done by other tools like SWIG and tolua++. Lua-icxx provides what those and other binding libs typically do not provide (easy access to a Lua interpreter from a C++ application).