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

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

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];

This Policy is not configurable except for the standard options.

Chris Dolan <cdolan@cpan.org>

Copyright (c) 2006-2011 Chris Dolan.

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