#NAME

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

#AFFILIATION

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

#DESCRIPTION

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

#CONFIGURATION

This Policy is not configurable except for the standard options.

#AUTHOR

Elliot Shank <perl@galumph.com>

#COPYRIGHT

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.