Perl::Critic::Policy::ControlStructures::ProhibitNegativeExpressionsInUnlessAndUntilConditions(3)

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.

SEE ALSO
Perl::Critic::Policy::ControlStructures::ProhibitUnlessBlocks

AUTHOR
Elliot Shank "<perl@galumph.com>"

COPYRIGHT
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.