in reply to kind of effort required for learning OO perl ?!
If you know about packages and references, then taking the next step to OO Perl is easy. You use bless to put a little note on a reference, which will be the package for looking up methods. So whenever you do $obj->foo, it's looking up the foo() subroutine in the package you bless'd into.
For the basics, there isn't much more to it then that. The trick is not making it out to be more complicated than it is. OO Perl is just straightforward combinations of stuff you probably already know.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.