John Maclean wrote:
> Say I've got 
> str = IO.read("testfile_for_using_file_open")
> how can Idetermone what class this object belongs to?

John, you can use the Object#class method.
In your case:

str.class

Use "ri class" for more info.

Cheers,
Antonio
-- 
Antonio Cangiano
My Ruby blog: http://www.antoniocangiano.com