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

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

       Chris Dolan <cdolan@cpan.org>

       This Policy is not configurable except for the standard options.

       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.

perl v5.40.0                                       2024-10-28              Perl::Critic::...NegativeIndices(3pm)

       Perl treats a negative array subscript as an offset from the end. Given this, the preferred way to get
       the last element is $x[-1], not $x[$#x] or $x[@x-1], and the preferred way to get the next-to-last is
       $x[-2], not "$x[$#x-1" or $x[@x-2].

       The biggest argument against the non-preferred forms is that theirsemanticschange when the computed
       index becomes negative. If @x contains at least two elements, $x[$#x-1] and $x[@x-2] are equivalent to
       $x[-2]. But if it contains a single element, $x[$#x-1] and $x[@x-2] are both equivalent to $x[-1]. Simply
       put, the preferred form is more likely to do what you actually want.

       As Conway points out, the preferred forms also perform better, are more readable, and are easier to
       maintain.

       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];

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