use strict;
use warnings;
use 5.010;

use Data::Dumper;

package foo;

sub new {
  my $class = shift;
  my $self  = {
    state => 'uninitialized',
  };

  bless $self, ref($class)||$class;

  return $self;
}

sub state {
  my $self = shift;
 
  return $self->{state};
}

sub set_state {
  my $self = shift;
  my $value = shift;

  $self->{state} = $value;
}

package main;

# make new object
my $foo = foo->new;

# show initial state
say $foo->state;

# change state
$foo->set_state('other value');

# show new state
say $foo->state;

# see what is $foo
say "This is \$foo:\n",
  Data::Dumper->new( [ $foo ], [ '*foo' ] )->Dump;