best way of testing a program exists before using it?

[Nick Craig-Wood]

Tim Golden <tim.golden at viacom-outdoor.co.uk> wrote:
>  Also, I just looked at the implementation in posixmodule.c,
>  and at the msdn article on its use, and at a thread in python-dev
>  a year or so ago. The last -- where someone was proposing more
>  specifics if the call fails -- didn't really go anywhere, and is
>  full of people (GvR and others) saying: don't use os.access unless...
> 
>  The msdn article: http://msdn2.microsoft.com/en-us/library/1w06ktdy.aspx
>  doesn't even seem to suggest that checking for executableness is a
>  possibility, and I think that the posixmodule.c code is simply
>  swallowing any non-OK return value and saying: No. (The msdn page
>  suggests that invalid parameters will return EINVAL).
> 
>  All that said, I think the only thing would be to add a line to
>  the docs saying sthg like: This will always return False for X_OK under
>  Win32. I'm happy to submit the patch, but is it worth it?

Wouldn't returning X_OK as true if the file exists be more sensible?
Ie the file might be executable, you'll have to try it, rather than,
no this file is definitely not executable...

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick