http://www.perlmonks.org?node_id=315540


in reply to Re: Foo is not a Bar, why?
in thread Foo is not a Bar, why?

Or using the nicer-looking use base. It will complain that the Bar package is empty, so I put a sub in it, but then it works fine.
my $foo = Foo->new; print "foo is".($foo->isa( 'Bar' ) ? '' : ' _not_')." a Bar\n"; package Bar; sub null {} package Foo; use base Bar; sub new { bless {},shift }