# in Plugin.pm:
package Plugin;  # the common base class

sub new {
  my $type = shift;
  my $class = ref($type) || $type;

  return bless {}, $class;
}

# the public entry point, calls a private entry point in each derived class, _do_stuff(), to actually do the work
sub do_stuff {
  my $self = shift;

  die 'Illegal plugin function' unless ($self->can('_do_stuff'));

  # polymorphic method call
  return $self->_do_stuff();
}

# in Whatever.pm:
package Whatever;

use base qw( Plugin );  # subclass of Plugin

sub new {
  my $type = shift;
  my $class = ref($type) || $type;

  return bless $class->SUPER::new, $class;
}

sub _do_stuff {
  # whatever this plugin does goes here
}

# etc.

##</code><code>##

use Basename;

for my $plugin_file ( ... ) {
  my $plugin_pkg = basename $pluginfile, '.pm';
  eval {
    use $plugin_pkg;
    my $plugin_object = new $plugin_pkg;
    $plugin_object->do_stuff();
  }
  if ($@) {
    # handle the error
  }
}