One way ( this was discussed in the CB recently ) is to use a factory, e.g.:

#!/usr/bin/perl

use warnings;
use strict;

package Class;

sub new { bless {}, $_[0] };

1;

package Class::SubclassA;

sub new { bless {}, $_[0]; };

1;


package Class::SubclassB;

sub new { return bless {}, $_[0]; };

1;

package ClassFactory;

my %creation_hash = (
  SubclassA => sub { Class::SubclassA->new() },
  SubclassB => sub { Class::SubclassB->new() }
);

sub create {
  shift;
  print $creation_hash{$_[0]}, "\n";
  return $creation_hash{$_[0]}->();
}

1;
package main;

my $a = ClassFactory->create( "SubclassA" );
my $b = ClassFactory->create( "SubclassB" );

print $a, "\n";
print $b, "\n";
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