Perl::Critic::Policy::ControlStructures::ProhibitNegativeExpressionsInUnlessAndUntilConditions - Don't use operators like not, !~, and le within until and unless.

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

    until ($foo ne 'blah') {          #not ok
        ...
    }

    while ($foo eq 'blah') {          #ok
        ...
    }

A number of people have problems figuring out the meaning of doubly negated expressions. unless and until are both negative constructs, so any negative (e.g. !~) or reversible operators (e.g. le) included in their conditional expressions are double negations. Conway considers the following operators to be difficult to understand within unless and until:

  ! not
  !~ ne !=
  <   >   <=  >=  <=>
  lt  gt  le  ge  cmp

This Policy is not configurable except for the standard options.

Perl::Critic::Policy::ControlStructures::ProhibitUnlessBlocks

Elliot Shank <perl@galumph.com>

Copyright (c) 2007-2011 Elliot Shank.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module.