use strict; # -*- cperl -*-
use warnings;

use lib qw( ../../../../lib );

=head1 NAME

Algorithm::Evolutionary::Fitness::String - Base class for string-based fitness functors


    package My::Own::Fitness;
    use base 'Algorithm::Evolutionary::Fitness::String'; #Mainly for deriving
    my $evaluator = new My::Own::Fitness;
    my $cache_hits = $evaluator->cached_evals();


Base class for fitness functions applied to string-based chromosomes;
extracts common code, and saves time. Provides a hash called C<%cache>
to be used as a, well, cache for evaluations. Assumes it's using the
C<_str> instance variable of the chromosome 

=head1 METHODS


package Algorithm::Evolutionary::Fitness::String;

our $VERSION =  '3.0' ;

use Carp qw( croak );
use base qw(Algorithm::Evolutionary::Fitness::Base);

=head2 new()

Initializes the cache


sub new {
  my $class = shift;
  my $self = { _cache => {} };
  bless $self, $class;
  return $self;

=head2 _apply( $individual )

Applies the instantiated problem to a chromosome, delegating to a specific function


sub _apply {
    my $self = shift;
    my $individual = shift;
    return  $self->_really_apply( $individual->{'_str'});

=head2 _really_apply( $string )

This one applies the function to the string. Should be overloaded


sub _really_apply {
  croak "This should be overriden";

=head2 cached_evals()

Returns the number of keys in the evaluation cache, which can be
compared to the total number of evaluations to find the cache hit


sub cached_evals {
  my $self = shift;
  return scalar keys %{$self->{'_cache'}};

=head1 Copyright
  This file is released under the GPL. See the LICENSE file included in this distribution,
  or go to