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Perl::Critic::Policy::ValuesAndExpressions::NotWithCompare(3) | User Contributed Perl Documentation | Perl::Critic::Policy::ValuesAndExpressions::NotWithCompare(3) |
NAME¶
Perl::Critic::Policy::ValuesAndExpressions::NotWithCompare - logical not used with compare
DESCRIPTION¶
This policy is part of the "Perl::Critic::Pulp" add-on. It picks up some cases of logical not "!" used with a comparison, like
! $x =~ /^[123]/ # bad ! $x + $y >= $z # bad
In each case precedence means Perl parses this as "(!$x)", like
(! $x) =~ /^[123]/ (! $x) + $y >= $z
rather than a negated comparison. Usually this is a mistake, so this policy is under the "bugs" theme (see "POLICY THEMES" in Perl::Critic).
As a special case, "!" on both sides of "==" or "!=" is allowed, since it's quite a good way to compare booleans.
!$x == !$y # ok !$x != !$y # ok
LIMITATIONS¶
User functions called without parentheses are assumed to be usual varargs style. But a prototype may mean that's not the case, letting a bad "!"-with-compare expression to go undetected.
! userfunc $x == 123 # indeterminate # without prototype would be ok: ! (userfunc ($x==123)) # with ($) prototype would be bad: (! userfunc($x)) == 123
Perl builtins with no args, and constant subs created with "use constant" or "sub FOO () {...}" in the file under test are recognised. Hopefully anything else too weird is rare.
! time == 1 # bad use constant FIVE => 5; ! FIVE < 1 # bad sub name () { "foo" } ! name =~ /bar/ # bad
SEE ALSO¶
Perl::Critic::Pulp, Perl::Critic
HOME PAGE¶
COPYRIGHT¶
Copyright 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019, 2021 Kevin Ryde
Perl-Critic-Pulp is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
Perl-Critic-Pulp is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Perl-Critic-Pulp. If not, see <http://www.gnu.org/licenses/>.
2021-03-01 | perl v5.40.0 |