This is Perl module WeakRef::Auto. INSTALLATION WeakRef::Auto installation is straightforward. If your CPAN shell is set up, you should just be able to do $ cpan WeakRef::Auto Download it, unpack it, then build it as per the usual: $ perl Makefile.PL $ make && make test Then install it: $ make install DOCUMENTATION WeakRef::Auto documentation is available as in POD. So you can do: $ perldoc WeakRef::Auto to read the documentation online with your favorite pager. Goro Fuji