lua_pcall returns a value 2 - Printable Version

lua_pcall returns a value 2 - Printable Version

+- iDevGames Forums (http://www.idevgames.com/forums)
+-- Forum: Development Zone (/forum-3.html)
+--- Forum: Programming Languages & Scripting (/forum-8.html)
+--- Thread: lua_pcall returns a value 2 (/thread-9932.html)

lua_pcall returns a value 2 - knowledge_seeker - Mar 15, 2012 09:27 PM

I have a test.lua file that contains the following code

Code:

function lFunction() 

print("Hello From Lua!")

 end

I am trying to run that code using the dofile method:

Code:

.....

  lua_State *L = lua_open();

  luaL_openlibs(L);

  int returnvalue1 = luaL_dofile(L,"test.lua");

  cout<<"The return value from the dofile method is: "<<returnvalue1<<" \n";

  lua_getglobal(L, "lFunction");

  lua_pcall(L, 0, 0, 0);

  int returnvalue2=  lua_pcall(L, 0, 0, 0);

  cout<<"The return value from the lua_pcall method is: "<<returnvalue2<<" \n";

  lua_close(L);

  .....

The return value from the dofile method is 0
The return value from the lua_pcall method is: 2

what can i do to fix it ? why am i getting an error with such a simple code ??

RE: lua_pcall returns a value 2 - OneSadCookie - Mar 15, 2012 10:57 PM

you have (accidentally, I guess) 2 calls to lua_pcall, the first of which will consume the function, and the second of which will error on the empty stack.

RE: lua_pcall returns a value 2 - knowledge_seeker - Mar 16, 2012 10:37 AM

(Mar 15, 2012 10:57 PM)OneSadCookie Wrote: you have (accidentally, I guess) 2 calls to lua_pcall, the first of which will consume the function, and the second of which will error on the empty stack.

I fixed that and im still getting the same error...please help

RE: lua_pcall returns a value 2 - Oddity007 - Mar 16, 2012 06:05 PM

You should really use better error handling to make errors more meaningful than simple numbers.

Documentation of lua_pcall:
http://pgl.yoyo.org/luai/i/lua_pcall

Quote:In case of runtime errors, this function will be called with the error message and its return value will be the message returned on the stack by lua_pcall.

(The return value is a string holding the error message)

A return value of two corresponds to LUA_ERRRUN, meaning an error running the code, according to the headers

Code:

/* thread status; 0 is OK */

#define LUA_YIELD    1

#define LUA_ERRRUN    2

#define LUA_ERRSYNTAX    3

#define LUA_ERRMEM    4

#define LUA_ERRERR    5

To get your proper error message, get the value on the top of the stack and print it:

Code:

lua_State *L = lua_open();

luaL_openlibs(L);

int errorCode = 0;

if(errorCode = luaL_dofile(L,"test.lua"))

{

    puts(lua_tostring(L, -1));

    abort();

}

lua_getglobal(L, "lFunction");

if(errorCode = lua_pcall(L, 0, 0, 0))

{

    puts(lua_tostring(L, -1));

    abort();

}

lua_close(L);

[/quote]