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