Using a Lua script in a FreePascal program

[Cybermonkey]

Ok, I see. That's a bit more complicated than the other way but it's possible. I am using the Lua52 headers which can be found on: http://lua-users.org/wiki/LuaInFreePascal
I'll post a simple example where two integers are added and the sum is returned to the Pascal program, it shouldn't be that hard to adapt it to a string/boolean function.
First the Lua script:

-- add two numbers

function add (x,y)
 return (x+y)
end

That's fairly simple. Now the Pascal program (console only). After compiling one has to specify the Lua script as a parameter on the console.

program callLua;
{$mode objfpc}{$H+}

uses sysutils,lua52;

var L : plua_state;
script:string;
sum:integer;

function luaadd (x,y:integer):integer ;
var sum:integer;
begin
    //* the function name */
    lua_getglobal(L, 'add');

    //* the first argument */
    lua_pushinteger(L, x);

    //* the second argument */
    lua_pushinteger(L, y);

    //* call the function with 2 arguments, return 1 result */
    lua_call(L, 2, 1);

    //* get the result */
    sum := (lua_tointeger(L, -1));
    lua_pop(L, 1);

    result:= sum;
end;



begin

if (ParamCount > 0)  then
begin
  script := pChar(ParamStr(1));
  L:=luaL_newstate();
  luaL_openlibs(L);

 if (luaL_dofile(L,pChar( script)))<>0 then 
   begin
//show if an error occured
    writeln(lua_tostring(L, -1));
  end;
  
  sum:=luaadd(12,3 );
    
  lua_close(L);
  writeln (sum);
end;
end.

The result should be 15 of course.