Data::Comparable - Present your object for comparison purposes

version 1.100840

  use base 'Data::Comparable';

  sub prepare_comparable {
      my $self = shift;
      $self->SUPER::prepare_comparable(@_);
      delete $self->{some_temp_value};
      $self->items;    # autovivify;
  }

  # in some test file:

  use Test::Differences;
  my $x = '...';
  my $y = '...';
  eq_or_diff($x->comparable, $y->comparable, 'objects are equal');

When you define a class, it may not be so straightforward to compare two objects of that class. For example, you want to compare object $x to object $y. You would like to use is_deeply() from Test::More, but it complains that some hash keys are undef in one object but completely missing in the other. That is easily solved by autovivifying the keys in question. Also, some hash keys might be irrelevant to comparison - that is, you still consider two objects to be equal even though they differ in some hash keys.

This is where Data::Comparable can help. It enables you to define how your object wants to look like when it is being passed to some deep comparison function like Test::More::is_deeply() or Test::Differences::eq_or_diff(). If your class inherits from Data::Comparable, it gets a method called comparable(), which you can call when comparing it. That is, you don't compare the actual objects, but their comparable versions.

To define the comparable version of your object, your class has to implement the prepare_comparable() method. There you can autovivify any hash keys you like or tweak your object in any way you need to make it comparable.

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See perlmodinstall for information and options on installing Perl modules.

No bugs have been reported.

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=Data-Comparable.

The latest version of this module is available from the Comprehensive Perl Archive Network (CPAN). Visit http://www.perl.com/CPAN/ to find a CPAN site near you, or see http://search.cpan.org/dist/Data-Comparable/.

The development version lives at http://github.com/hanekomu/Data-Comparable/. Instead of sending patches, please fork this project using the standard git and github infrastructure.

  Marcel Gruenauer <marcel@cpan.org>

This software is copyright (c) 2004 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.