my $ui = UI->new;
$ui->query_dialog( { search_with => 'DB::File' } );

package UI;
sub query_dialog {
	my( $self, $args ) =@_;
	print "Name? ";
	my $name = <STDIN>;
	my $search_class = $args->{search_with};
	my @files = $search_class->search( { name => $name } );
	...
}