$ perl -Mstrict -Mwarnings -le '
    package Parent;
    sub new { bless {} => $_[0] }
    sub call { $_[0]->char }
    sub char { ref $_[0] }

    package Son;
    use base "Parent";

    package main;
    my $parent_obj = Parent->new;
    print "\$parent_obj class = ", $parent_obj->call;

    my $son_obj = Son->new;
    print "\$son_obj class = ", $son_obj->call;
'
$parent_obj class = Parent
$son_obj class = Son