NAME

Perl::Critic::Policy::Variables::RequireNegativeIndices - Negative array index should be used.

AFFILIATION

This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

Conway points out that

  $arr[$#arr];
  $arr[$#arr-1];
  $arr[@arr-1];
  $arr[@arr-2];

are equivalent to

  $arr[-1];
  $arr[-2];
  $arr[-1];
  $arr[-2];

and the latter are more readable, performant and maintainable. The latter is because the programmer no longer needs to keep two variable names matched.

This policy notices all of the simple forms of the above problem, but does not recognize any of these more complex examples:

   $some->[$data_structure]->[$#{$some->[$data_structure]} -1];
   my $ref = \@arr;
   $ref->[$#arr];

CONFIGURATION

This Policy is not configurable except for the standard options.

AUTHOR

Chris Dolan <cdolan@cpan.org>

COPYRIGHT

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