Safe Lua invoke C++ registered function -

hey,everyone! i've c++ app embedded lua script. non-programmer edits lua script, c++ app invoke lua script , lua script invokes c++ registered function.

i use luaplus above job. question is: when script-editor makes mistakes such misspelling the parameter, c++ app crashes! can prevent happening? thanks

look @ lua_cpcall , lua_pcall. both allow protected function calls of lua in c. if return non-negative number call failed , lua stack contains error string. in cpcalls case stack otherwise unmodified. pcall you'll need @ lua_pushcclosure invoke cfunction safely.

what this: create c function of lua_* calls want, such loadfile , dofile. call function using lua_cpcall or lua_pushcclosure amd lua_pcall. allows detect if error occured in t function passed cpcall.

examples:

function hello() {   string hello_ = "hello lua!";   struct c {     static int call(lua_state* l) {       c *p = static_cast<c*>(lua_touserdata(l,-1));       lua_pushstring(l, p->str.c_str() );       lua_getglobal(l, "print");        lua_call(l, 1, 0); //ok       lua_pushstring(l, p->str.c_str() );       lua_getglobal(l, "notprint");        lua_call(l, 1, 0); //error -> longjmps       return 0; //number of values on stack 'return' lua     }     const string& str;   } p = { hello_ };   //protected call of c::call() above   //with &p 1st/only element on lua stack   //any errors encountered trigger longjmp out of lua ,   //return non-0 error code , string on stack   //a return of 0 indicates success , stack unmodified   //to invoke lua functions safely use lua_pcall function   int res = lua_cpcall(l, &c::call, &p);   if( res ) {     string err = lua_tostring(l, -1);     lua_pop(l, 1);     //error hanlder here   }   //load .lua file   if( (res=lual_loadfile(l, "myluafile.lua")) ) {     string err = lua_tostring(l, -1);     lua_pop(l, 1);     //res 1 of     //lua_errsyntax - lua syntax error     //lua_errmem    - out of memory error     //lue_errfile   - file not found/accessible error   }   //execute   if( (res=lua_pcall(l,0,0,0)) ) {     string err = lua_tostring(l, -1);     lua_pop(l, 1);     // res 1 of     // lua_errrun: runtime error.     // lua_errmem: memory allocation error.     // lua_errerr: error while running error handler function (null in case).   }   // try call [a_int,b_str] = foo(1,2,"3")   lua_getglobal(l,"foo");   if( lua_isfunction(l,lua_gettop(l)) ) { //foo exists     lua_pushnumber(l,1);     lua_pushnumber(l,2);     lua_pushstring(l,"3");     lua_pushvalue(l, -4); //copy of foo()      if( (res = lua_pcall(l, 3, 2, 0/*default error func*/)) ) {       string err = lua_tostring(l, -1);       lua_pop(l, 1);       //error: see above     }     int a_int = (int)lua_tointeger(l,-2);     string b_str = lua_tostring(l,-1);     lua_pop(l,2+1); //2 returns, + copy of foo()   } }