Re: cannot index a table loaded as a chunk

[Ben Sunshine-Hill <sneftel@...>]

Well, the Lua side looks fine. I suggest you check the return value of
lua_dofile to see if the file is being loaded in appropriately.

On Fri, 20 Aug 2004 03:00:12 -0700, Michael Newberry
<mnewberry@axres.com> wrote:
> I show the source code below. I understand the difference between
> LuaL_loadfile and lua_dofile. Originally, I tried using lua_dofile and that
> did not work so I tried luaL_loadfile and that didn;t work either. But I'm
> wondering about a couple of Windows things. First, can lua_dofile handle
> file names with blank spaces in them. Second, this worked as of yesterday,
> so could there any weirdness from the XP Service Pack 2 and file access
> after my machine has been gobling up little bits and pieces of SP2 from the
> internet day by day? Just a couple of thoughts.
> 
> Here is some source code fro the 3 players, separated by /////...
> 
> ////////////////////////////////////////////////////////////////////////////
> //////////////
> // the C function that includes a lua script file in the current script
> int LuaInclude( struct lua_State* L )
> {
>   if ( lua_gettop( L ) == 1 )
>   {
>     CString sPath = lua_tostring( L, 1 );
>     CSplitPath path( sPath );
> 
>     if ( _tcsclen( path.GetDrive() ) == 0 ) // full path not passed, default
> to script folder
>     {
>        path.SetPath("");
>        path.SetFolder( g_sScriptsPath ); // folder where the scripts are
> located
>        path.SetFileNameExt( sPath ); // the filename that was passed
>        lua_dofile( L, (LPCTSTR)path.Merge() );
>     }
>     else
>        lua_dofile( L, (LPCTSTR)sPath );
>   }
>   return 0;
> }
> 
> ////////////////////////////////////////////////////////////////////////////
> //////////////
> //// the lua script.  This is run by lua_pcall( L, ...)
> 
> Include("Img.lua")
> 
> -- 1. select the names of images from a folder. Two will be needed.
> 
> -- get the first image
> sName1, bSuccess = ReqFileName() -- get the name of an image file
> if ( not bSuccess ) then
>   Exit("Open dialog canceled");
> end
> 
> Img1 = Img:new()
> ^^^^ script fails right here saying that Img is nil and can;t be indexed.
> 
> ////////////////////////////////////////////////////////////////////////////
> //////////////
> //// The c;ass 'Img.lua'. This is supposed to be loaded into the main script
> by the Include statement:
> 
> if not Img then --// begin definition block //////////////////
> 
> Img = { _I = nil }    -- Constructor, holds a pointer to the C++ image
> object
> 
> --//////// from the book, p.138
> ////////////////////////////////////////////////
> -- Method: Creates a new instance of an Img
> -- Input: nothing
> -- Returns: new Img object
> function Img:new(o)
>   o = o or {}
>   setmetatable(o,self)
>   self.__index = self
>   o._I = nil
>   return o
> end
> 
>     <<<< and more functions defined for the class >>>
> end
> ------------------
> 
> And yes, I checked that the path given to lua_dofile in the C function is
> good.
> 
> Michael
> 
> 
> 
> ----- Original Message -----
> From: "Ben Sunshine-Hill" <sneftel@gmail.com>
> To: "Lua list" <lua@bazar2.conectiva.com.br>
> Sent: Friday, August 20, 2004 1:52 AM
> Subject: Re: cannot index a table loaded as a chunk
> 
> > I'm wildly guessing you're executing luaL_loadfile, but never
> > executing the resultant chunk.
> >
> > A chunk is a function. That's all it is. Commonly, it's a function
> > which happens to set a lot of global variables, but that's more a
> > convention than anything else. The point is, all luaL_loadfile does is
> > push a function onto the stack. If you don't execute it, it does
> > nothing.
> >
> > Of course, it's possible your problem lies elsewhere entirely. If so,
> > post your code... it makes it much easier to troubleshoot.
> >
> > Ben
> >
> > On Fri, 20 Aug 2004 01:33:23 -0700, Michael Newberry
> > <mnewberry@axres.com> wrote:
> > > Sorry about the problems of clarity and the typos in my previous
> message. It
> > > is 1:30 in the morning and I have been wrestling with this problem all
> > > evening.
> > >
> > > Michael
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Michael Newberry" <mnewberry@axres.com>
> > > To: "Lua list" <lua@bazar2.conectiva.com.br>
> > > Sent: Friday, August 20, 2004 1:29 AM
> > > Subject: cannot index a table loaded as a chunk
> > >
> > > > I am using lus 5.0 and I have a strange problem with tables being used
> as
> > > > classes. I define the class as a table. It has one variable inside.The
> > > > scripthas a command that calls a Cfunction named Include(filename)
> which
> > > > itself uses luaL_loadfile() to load a class definition named Img. When
> the
> > > > main chunk gets to Img:new()  [as on page 138 of the lua book], it
> fails
> > > > with this message from lua:
> > > >
> > > >     "... : attempt to index global `Img' (a nil value)"
> > > >
> > > > In other words, the table Img defined in a separate file is considered
> not
> > > > yet defined. it is almost as if each chuck is having its own set of
> > > "static"
> > > > globals rather than merging them into a single pool.
> > > >
> > > > Ideas?
> > > >
> > > > Michael
> > > >
> > > >
> > > >
> > >
> > >
> 
>