runtime location discovery

[Geoff Gerrietts]

I'm writing a program designed for maximal flexibility, with minimal
dependencies.

The other night, I tried to put in a chunk of code that allowed the
program to be executed from an arbitrary location (like a user's home
directory) without previously knowing where we were installed
(allowing the app to be installed wherever it seems most natural to
the system administrator).

The code I wrote did this:
    root_location = os.path.dirname(sys.argv[0])

Later, I could use root_location as a prefix in statemnts like:
    Image.open(os.path.join(root_location, "image/naked_chicks.png"))

or whatever ;)

That worked famously, but infamy was a mere logical step away.

When I created a symlink to the script, it went shopping for the 
resource files at all in ~geoff/bin/ instead of ~geoff/src/sp/.
Obviously, it didn't find them.

Now I can go look for symlinks and resolve them, that's not a problem.
But a hard link would create the same problem all over again. So I'm
curious -- this can't be an uncommon hurdle to hop. How have other
people solved the problem?

Thanks,
--G.

-- 
Geoff Gerrietts <geoff at gerrietts dot net>      http://www.gerrietts.net/
   "If I were two-faced, would I be wearing this one?" --Abraham Lincoln