package Foo::Parse;

#...

sub parse {
  my $self = shift;
  if (my $func = $self->can('action'))
  {
    $self->$func(@_);
  }
}

#...

package Foo::Parse::Splitter

use base 'Foo::Parse';

sub action {
  my $self = shift;
  # ...
}

package main;

my $fp = Foo::Parse::Splitter->new('FooParser');
$fp->parse($_) while <>;

##</code><code>##

my $fp;
$fp = Foo::Parse->new('FooParser',
  sub {
    local $_ = shift;
    s/^\w+:// or
      $fp->warn("something wrong!");
    split /,/;
  } );