Inferring the location of a Lua script

[Lorenzo Donati <lorenzo.donati.bz@...>]

Hi everybody!

I'm a Lua newbie and I've been lurking on this list for some months.

<compliments>
Very nice language. I learnt about it because it is embedded in my 
favourite editor (SciTE). I must admit at first I was puzzled because I 
had never heard anything about it before and It looked quite different 
from the other languages I know (mainly Java, some C++, a bunch of 
different BASIC dialects and a bit of Python and, many years ago, some 
Pascal, C, Forth and Fortran). The real breakthrough in my programming 
experience using Lua has been functions as first class objects, (If only 
Java had them, instead of those crappy inner-classes!!! :-) .
I also greatly appreciate the kindness and friendliness of this list, 
which is not so common among those "inhabited" by technically savy 
people or IT professionals!
</compliments>

Now to the point.
I need a way to make a Lua script know it's exact location, i.e. its 
absolute file system path (under Win XP is enough) using pure Lua and no 
C. My purpose is to build applications in pure Lua (or wxLua) that can 
automatically find their modules/components/data without any 
installation or shell script launcher (I'm playing with executables 
created using wxLuafreeze and plan also to use srlua to achieve a 
similar effect with plain Lua).
I've searched the archive but found only some suggestions to parse 
arg[0], but this doesn't always work. In particular there are two use 
cases where it fails:

1. When invoking a script specifiying a relative path (that path is what 
arg[0] gets) like in the following invocation:
lua relative_path\myscript.lua

2. When invoking through a relative path an executables that is obtained 
freezing a wxLua script and this latter looks for another file using a 
path relative to the executable.
relative_path\myWxLuaFrozenApp.exe   ----> generates a file not found error

I'm missing something?
Thank you in advance. Any help or direction is appreciated.

Lorenzo Donati

P.S.: I apologize in advance for my possible future late replies, since 
I'm not always connected to the internet and, for various reasons, 
cannot connect frequently.