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";

[download]

In reply to Re: Object loading at runtime by Transient
in thread Object loading at runtime by benrwebb

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.