CentOS 7.0 - man page for perl::critic::policy::variables::requirenegativeindices (centos section 3)
|Linux & Unix Commands - Search Man Pages
Perl::Critic::Policy::Variables::RequireNegativeIndices - Negative array index should be
This Policy is part of the core Perl::Critic distribution.
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 their semantics change 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:
my $ref = \@arr; $ref->[$#arr];
This Policy is not configurable except for the standard options.
Chris Dolan <firstname.lastname@example.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.
perl v5.16.3 Perl::Critic::Policy::Variables::RequireNegativeIndices(3)
All times are GMT -4. The time now is 05:29 PM.