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

NAME AFFILIATION DESCRIPTION CONFIGURATION SEE ALSO AUTHOR COPYRIGHT

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