Looking at your code, I think one thing that you're missing is that the $self you create in new is also available in display. You could do this:

sub display {
    my $self = shift;

    my $link_file = $self->{link_file};
    my $adate     = $self->{adate};
    # etc.
}
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That's true as long as display is called as an instance method (i.e., as you say, $whatever->display()). Called as a class method (Records_tagged->display()), all it gets for $self is the string, 'Records_tagged'.