NAME

Data::Range::Compare::Cookbook::Instance_and_Constants - Look inside the instance

SYNOPSIS

package a_to_z;
use strict;
use warnings;
use vars qw(@ISA @list %ids %helper);
use Data::Range::Compare qw(:KEYS);
@ISA=qw(Data::Range::Compare);

use constant key_ids=>6;

@list=('a' .. 'z');
my $id=-1;
%ids=map { ($_,++$id) } @list; 
undef $id;

$helper{add_one}=\&add_one;
sub add_one {
  my $here=$ids{$_[0]};
  ++$here;
  return 'z' if $#list<$here;
  $list[$here]
}

$helper{sub_one}=\&sub_one;
sub sub_one {
  my $here=$ids{$_[0]};
  --$here;
  return 'a' if $here<0;
  $list[$here]
}
sub cmp_values { $_[0] cmp $_[1] }
$helper{cmp_values}=\&cmp_values;

sub new{
  my ($class,$start,$end,$generated,$missing)=@_;
  my $s=$class->SUPER::new(\%helper,$start,$end,$generated,$missing);
  $s->[key_ids]=\%ids;
  $s;
}

sub letter_ids { %{$_[0]->[key_ids]} }

sub range_compare { 
   my ($s,@args)=@_;
   $s->SUPER::range_compare(\%helper,@args) 
}

sub get_common_range {
  my ($class,@args)=@_;
  $class->SUPER::get_common_range(\%helper,@args);
}

sub first_letter () { $_[0]->[key_start] }

sub last_letter () { $_[0]->[key_end] }

1;

Using a_to_z.pm

Now you can create a perl script to load a_to_z and use the simplified functionality.

use a_to_z;

my $obj_a=a_to_z->new(qw(c f));
my $obj_b=a_to_z->new(qw(a z));
my $obj_c=a_to_z->new(qw(g j));

$list=[ [$obj_a] ,[$obj_b] ,[$obj_c] ];
$sub=a_to_z->range_compare($list);
while(my @row=$sub->()) { 
 my ($obj_a,$obj_b,$obj_c)=@row;
 my $common_range=a_to_z-->get_common_range(\@row);
 print "\n";
 print "Common Range: $common_range\n";
 my ($obj_a,$obj_b,$obj_c)=@row;
 my $range_a_state=$obj_a->missing ?
      'Not in set a'
      :
      'in set a';
      my $range_b_state=$obj_b->missing ?
      'Not in set b'
      :
      'in set b';
      my $range_c_state=$obj_c->missing ?
      'Not in set c'
      :
      'in set c';

      print "Range_a: $obj_a is $range_a_state\n";
      print "Range_b: $obj_b is $range_b_state\n";
      print "Range_c: $obj_c is $range_c_state\n";
}

Output:
Common Range: a - b
Range_a: a - b is Not in set a
Range_b: a - z is in set b
Range_c: a - f is Not in set c

Common Range: c - f
Range_a: c - f is in set a
Range_b: a - z is in set b
Range_c: a - f is Not in set c

Common Range: g - j
Range_a: g - z is Not in set a
Range_b: a - z is in set b
Range_c: g - j is in set c

Common Range: k - z
Range_a: g - z is Not in set a
Range_b: a - z is in set b
Range_c: k - z is Not in set c

DESCRIPTION

Simple example demonstrating HOWTO subclass the "a to z" example

CONSTANTS

Data::Range::Compare instances are array references and use numeric entries to identify each element.

• key_helper

  This constant represents the position of \%helper in the array instance.

  The value of key_helper is 0

• key_start

  This constant represents the position of $start in this instance.

  The value of key_start is 1

• key_end

  This constant represents the position of $end in this instance.

  The value of key_end is 2

• key_generated

  This constant represents the position of $generated in this instance.

  The value of key_generated is 3

• key_missing

  This constant represents the position of $missing in this instance.

  The value of key_missing is 4

• key_key_data

  This constant represents the position of $key_data in this instance.

  The value of key_key_data is 5

AUTHOR

Michael Shipper

COPYRIGHT

Copyright 2010 Michael Shipper. All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Data::Range::Compare::Cookbook perlboot