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).