If you are really adventerous you could try Class::Maker (badly documented though):

use Class::Maker qw(:all);

class 'Zoo',
{
  public =>
  {
    array => [qw( animals )],
  }
};

class 'Animal',
{
  public =>
  {
    string => [qw( name )],
  }
};

class 'Camel',
{
  isa => [qw( Animal )],
};

class 'Lama',
{
  isa => [qw( Animal )],
};

   my $z = Zoo->new();

   push @{ $z->animals }, Camel->new( name => 'Murat' );
[download]

It provides a default constructor which is quite elegant. Good Luck, Murat