use v5.14;
use warnings;
use DBI ();

package MyApp {
   use Class::Tiny qw( version dbh output_file );
   
   sub do_something {
      my $self = shift;
      if ( $self->version < 1.0 ) {  # an object attribute
         $self->do_something_simple;
      }
      else {
         $self->do_something_complex;
      }
   }
   
   sub do_something_simple {
      my $self = shift;
      open my $fh, '>', $self->output_file or die;
      print $fh "Hello world\n";
      close $fh;
   }
   
   sub do_something_complex {
      my $self = shift;
      open my $fh, '>', $self->output_file or die;
      print $fh "Hello world\n";
      printf $fh "There are %d rows in the table.\n",
         $self->dbh->do("SELECT 1 FROM my_table");
      close $fh;
   }
}

my $app = MyApp->new(
   version      => 1.2,
   dbh          => DBI->connect("dbi:SQLite:dbname=myapp.sqlite"),
   output_file  => '/tmp/output.txt',
);
$app->do_something;