Checking for a writeable or readable file

[Geoff Leyland <geoff_leyland@...>]

Hi,

It's possible to check whether a variable is an open file with io.type.

Is it possible to check whether that file is readable?  Whether it's writeable?  (I know I could try reading or writing to the file, but if it worked the file wouldn't be in the same state any more).

Cheers,
Geoff