Perl::Critic::PolicySummary - Descriptions of the Policy modules included with Perl::Critic itself.

NAME

Perl::Critic::PolicySummary − Descriptions of the Policy modules included with Perl::Critic itself.

The following Policy modules are distributed with Perl::Critic. (There are additional Policies that can be found in add−on distributions.) The Policy modules have been categorized according to the table of contents in Damian Conway's book Perl Best Practices. Since most coding standards take the form "do this..." or "don't do that...", I have adopted the convention of naming each module "RequireSomething" or "ProhibitSomething". Each Policy is listed here with its default severity. If you don't agree with the default severity, you can change it in your .perlcriticrc file (try "perlcritic −−profile−proto" for a starting version). See the documentation of each module for its specific details.

POLICIES

BuiltinFunctions::ProhibitBooleanGrep

Use "any" from "List::Util", "List::SomeUtils", or "List::MoreUtils" instead of "grep" in boolean context. [Default severity 2]

BuiltinFunctions::ProhibitComplexMappings

Map blocks should have a single statement. [Default severity 3]

BuiltinFunctions::ProhibitLvalueSubstr

Use 4−argument "substr" instead of writing "substr($foo, 2, 6) = $bar". [Default severity 3]

BuiltinFunctions::ProhibitReverseSortBlock

Forbid $b before $a in sort blocks. [Default severity 1]

BuiltinFunctions::ProhibitShiftRef

Prohibit "\shift" in code [Default severity 3]

BuiltinFunctions::ProhibitSleepViaSelect

Use Time::HiRes instead of something like "select(undef, undef, undef, .05)". [Default severity 5]

BuiltinFunctions::ProhibitStringyEval

Write "eval { my $foo; bar($foo) }" instead of "eval "my $foo; bar($foo);"". [Default severity 5]

BuiltinFunctions::ProhibitStringySplit

Write "split /−/, $string" instead of "split '−', $string". [Default severity 2]

BuiltinFunctions::ProhibitUniversalCan

Write "eval { $foo−>can($name) }" instead of "UNIVERSAL::can($foo, $name)". [Default severity 3]

BuiltinFunctions::ProhibitUniversalIsa

Write "eval { $foo−>isa($pkg) }" instead of "UNIVERSAL::isa($foo, $pkg)". [Default severity 3]

BuiltinFunctions::ProhibitUselessTopic

Don't pass $_ to built−in functions that assume it, or to most filetest operators. [Default severity 2]

BuiltinFunctions::ProhibitVoidGrep

Don't use "grep" in void contexts. [Default severity 3]

BuiltinFunctions::ProhibitVoidMap

Don't use "map" in void contexts. [Default severity 3]

BuiltinFunctions::RequireBlockGrep

Write "grep { /$pattern/ } @list" instead of "grep /$pattern/, @list". [Default severity 4]

BuiltinFunctions::RequireBlockMap

Write "map { /$pattern/ } @list" instead of "map /$pattern/, @list". [Default severity 4]

BuiltinFunctions::RequireGlobFunction

Use "glob q{*}" instead of <*>. [Default severity 5]

BuiltinFunctions::RequireSimpleSortBlock

Sort blocks should have a single statement. [Default severity 3]

ClassHierarchies::ProhibitAutoloading

AUTOLOAD methods should be avoided. [Default severity 3]

ClassHierarchies::ProhibitExplicitISA

Employ "use parent" instead of @ISA. [Default severity 3]

ClassHierarchies::ProhibitOneArgBless

Write "bless {}, $class;" instead of just "bless {};". [Default severity 5]

CodeLayout::ProhibitHardTabs

Use spaces instead of tabs. [Default severity 3]

CodeLayout::ProhibitParensWithBuiltins

Write "open $handle, $path" instead of "open($handle, $path)". [Default severity 1]

CodeLayout::ProhibitQuotedWordLists

Write "qw(foo bar baz)" instead of "('foo', 'bar', 'baz')". [Default severity 2]

CodeLayout::ProhibitTrailingWhitespace

Don't use whitespace at the end of lines. [Default severity 1]

CodeLayout::RequireConsistentNewlines

Use the same newline through the source. [Default severity 4]

CodeLayout::RequireTidyCode

Must run code through perltidy. [Default severity 1]

CodeLayout::RequireTrailingCommas

Put a comma at the end of every multi−line list declaration, including the last one. [Default severity 1]

ControlStructures::ProhibitCStyleForLoops

Write for(0..20) instead of "for($i=0; $i<=20; $i++)". [Default severity 2]

ControlStructures::ProhibitCascadingIfElse

Don't write long "if−elsif−elsif−elsif−elsif...else" chains. [Default severity 3]

ControlStructures::ProhibitDeepNests

Don't write deeply nested loops and conditionals. [Default severity 3]

ControlStructures::ProhibitLabelsWithSpecialBlockNames

Don't use labels that are the same as the special block names. [Default severity 4]

ControlStructures::ProhibitMutatingListFunctions

Don't modify $_ in list functions. [Default severity 5]

ControlStructures::ProhibitNegativeExpressionsInUnlessAndUntilConditions

Don't use operators like "not", "!˜", and "le" within "until" and "unless". [Default severity 3]

ControlStructures::ProhibitPostfixControls

Write "if($condition){ do_something() }" instead of "do_something() if $condition". [Default severity 2]

ControlStructures::ProhibitUnlessBlocks

Write "if(! $condition)" instead of unless($condition). [Default severity 2]

ControlStructures::ProhibitUnreachableCode

Don't write code after an unconditional "die, exit, or next". [Default severity 4]

ControlStructures::ProhibitUntilBlocks

Write "while(! $condition)" instead of until($condition). [Default severity 2]

ControlStructures::ProhibitYadaOperator

Never use "..." in production code. [Default severity 4]

Documentation::PodSpelling

Check your spelling. [Default severity 1]

Documentation::RequirePackageMatchesPodName

The "=head1 NAME" section should match the package. [Default severity 1]

Documentation::RequirePodAtEnd

All POD should be after "__END__". [Default severity 1]

Documentation::RequirePodSections

Organize your POD into the customary sections. [Default severity 2]

ErrorHandling::RequireCarping

Use functions from Carp instead of "warn" or "die". [Default severity 3]

ErrorHandling::RequireCheckingReturnValueOfEval

You can't depend upon the value of $@/$EVAL_ERROR to tell whether an "eval" failed. [Default severity 3]

InputOutput::ProhibitBacktickOperators

Discourage stuff like "@files = `ls $directory`". [Default severity 3]

InputOutput::ProhibitBarewordDirHandles

Write "opendir my $dh, $dirname;" instead of "opendir DH, $dirname;". [Default severity 5]

InputOutput::ProhibitBarewordFileHandles

Write "open my $fh, q{<}, $filename;" instead of "open FH, q{<}, $filename;". [Default severity 5]

InputOutput::ProhibitExplicitStdin

Use "<>" or "<ARGV>" or a prompting module instead of "<STDIN>". [Default severity 4]

InputOutput::ProhibitInteractiveTest

Use prompt() instead of −t. [Default severity 5]

InputOutput::ProhibitJoinedReadline

Use "local $/ = undef" or Path::Tiny instead of joined readline. [Default severity 3]

InputOutput::ProhibitOneArgSelect

Never write select($fh). [Default severity 4]

InputOutput::ProhibitReadlineInForLoop

Write "while( $line = <> ){...}" instead of "for(<>){...}". [Default severity 4]

InputOutput::ProhibitTwoArgOpen

Write "open $fh, q{<}, $filename;" instead of "open $fh, "<$filename";". [Default severity 5]

InputOutput::RequireBracedFileHandleWithPrint

Write "print {$FH} $foo, $bar;" instead of "print $FH $foo, $bar;". [Default severity 1]

InputOutput::RequireBriefOpen

Close filehandles as soon as possible after opening them. [Default severity 4]

InputOutput::RequireCheckedClose

Write "my $error = close $fh;" instead of "close $fh;". [Default severity 2]

InputOutput::RequireCheckedOpen

Write "my $error = open $fh, $mode, $filename;" instead of "open $fh, $mode, $filename;". [Default severity 3]

InputOutput::RequireCheckedSyscalls

Return value of flagged function ignored. [Default severity 1]

InputOutput::RequireEncodingWithUTF8Layer

Write "open $fh, q{<:encoding(UTF−8)}, $filename;" instead of "open $fh, q{<:utf8}, $filename;". [Default severity 5]

Miscellanea::ProhibitFormats

Do not use "format". [Default severity 3]

Miscellanea::ProhibitTies

Do not use "tie". [Default severity 2]

Miscellanea::ProhibitUnrestrictedNoCritic

Forbid a bare "## no critic" [Default severity 3]

Miscellanea::ProhibitUselessNoCritic

Remove ineffective "## no critic" annotations. [Default severity 2]

Modules::ProhibitAutomaticExportation

Export symbols via @EXPORT_OK or %EXPORT_TAGS instead of @EXPORT. [Default severity 4]

Modules::ProhibitConditionalUseStatements

Avoid putting conditional logic around compile−time includes. [Default severity 3]

Modules::ProhibitEvilModules

Ban modules that aren't blessed by your shop. [Default severity 5]

Modules::ProhibitExcessMainComplexity

Minimize complexity in code that is outside of subroutines. [Default severity 3]

Modules::ProhibitMultiplePackages

Put packages (especially subclasses) in separate files. [Default severity 4]

Modules::RequireBarewordIncludes

Write "require Module" instead of "require 'Module.pm'". [Default severity 5]

Modules::RequireEndWithOne

End each module with an explicitly "1;" instead of some funky expression. [Default severity 4]

Modules::RequireExplicitPackage

Always make the "package" explicit. [Default severity 4]

Modules::RequireFilenameMatchesPackage

Package declaration must match filename. [Default severity 5]

Modules::RequireNoMatchVarsWithUseEnglish

"use English" must be passed a "−no_match_vars" argument. [Default severity 2]

Modules::RequireVersionVar

Give every module a $VERSION number. [Default severity 2]

NamingConventions::Capitalization

Distinguish different program components by case. [Default severity 1]

NamingConventions::ProhibitAmbiguousNames

Don't use vague variable or subroutine names like 'last' or 'record'. [Default severity 3]

Objects::ProhibitIndirectSyntax

Prohibit indirect object call syntax. [Default severity 4]

References::ProhibitDoubleSigils

Write "@{ $array_ref }" instead of @$array_ref. [Default severity 2]

RegularExpressions::ProhibitCaptureWithoutTest

Capture variable used outside conditional. [Default severity 3]

RegularExpressions::ProhibitComplexRegexes

Split long regexps into smaller "qr//" chunks. [Default severity 3]

RegularExpressions::ProhibitEnumeratedClasses

Use named character classes instead of explicit character lists. [Default severity 1]

RegularExpressions::ProhibitEscapedMetacharacters

Use character classes for literal meta−characters instead of escapes. [Default severity 1]

RegularExpressions::ProhibitFixedStringMatches

Use "eq" or hash instead of fixed−pattern regexps. [Default severity 2]

RegularExpressions::ProhibitSingleCharAlternation

Use "[abc]" instead of "a|b|c". [Default severity 1]

RegularExpressions::ProhibitUnusedCapture

Only use a capturing group if you plan to use the captured value. [Default severity 3]

RegularExpressions::ProhibitUnusualDelimiters

Use only "//" or "{}" to delimit regexps. [Default severity 1]

RegularExpressions::ProhibitUselessTopic

Don't use $_ to match against regexes. [Default severity 2]

RegularExpressions::RequireBracesForMultiline

Use "{" and "}" to delimit multi−line regexps. [Default severity 1]

RegularExpressions::RequireDotMatchAnything

Always use the "/s" modifier with regular expressions. [Default severity 2]

RegularExpressions::RequireExtendedFormatting

Always use the "/x" modifier with regular expressions. [Default severity 3]

RegularExpressions::RequireLineBoundaryMatching

Always use the "/m" modifier with regular expressions. [Default severity 2]

Subroutines::ProhibitAmpersandSigils

Don't call functions with a leading ampersand sigil. [Default severity 2]

Subroutines::ProhibitBuiltinHomonyms

Don't declare your own "open" function. [Default severity 4]

Subroutines::ProhibitExcessComplexity

Minimize complexity by factoring code into smaller subroutines. [Default severity 3]

Subroutines::ProhibitExplicitReturnUndef

Return failure with bare "return" instead of "return undef". [Default severity 5]

Subroutines::ProhibitManyArgs

Too many arguments. [Default severity 3]

Subroutines::ProhibitNestedSubs

"sub never { sub correct {} }". [Default severity 5]

Subroutines::ProhibitReturnSort

Behavior of "sort" is not defined if called in scalar context. [Default severity 5]

Subroutines::ProhibitSubroutinePrototypes

Don't write "sub my_function (@@) {}". [Default severity 5]

Subroutines::ProhibitUnusedPrivateSubroutines

Prevent unused private subroutines. [Default severity 3]

Subroutines::ProtectPrivateSubs

Prevent access to private subs in other packages. [Default severity 3]

Subroutines::RequireArgUnpacking

Always unpack @_ first. [Default severity 4]

Subroutines::RequireFinalReturn

End every path through a subroutine with an explicit "return" statement. [Default severity 4]

TestingAndDebugging::ProhibitNoStrict

Prohibit various flavors of "no strict". [Default severity 5]

TestingAndDebugging::ProhibitNoWarnings

Prohibit various flavors of "no warnings". [Default severity 4]

TestingAndDebugging::ProhibitProlongedStrictureOverride

Don't turn off strict for large blocks of code. [Default severity 4]

TestingAndDebugging::RequireTestLabels

Tests should all have labels. [Default severity 3]

TestingAndDebugging::RequireUseStrict

Always "use strict". [Default severity 5]

TestingAndDebugging::RequireUseWarnings

Always "use warnings". [Default severity 4]

ValuesAndExpressions::ProhibitCommaSeparatedStatements

Don't use the comma operator as a statement separator. [Default severity 4]

ValuesAndExpressions::ProhibitComplexVersion

Prohibit version values from outside the module. [Default severity 3]

ValuesAndExpressions::ProhibitConstantPragma

Don't "use constant FOO => 15". [Default severity 4]

ValuesAndExpressions::ProhibitEmptyQuotes

Write "q{}" instead of ''. [Default severity 2]

ValuesAndExpressions::ProhibitEscapedCharacters

Write "\N{DELETE}" instead of "\x7F", etc. [Default severity 2]

ValuesAndExpressions::ProhibitImplicitNewlines

Use concatenation or HEREDOCs instead of literal line breaks in strings. [Default severity 3]

ValuesAndExpressions::ProhibitInterpolationOfLiterals

Always use single quotes for literal strings. [Default severity 1]

ValuesAndExpressions::ProhibitLeadingZeros

Write oct(755) instead of 0755. [Default severity 5]

ValuesAndExpressions::ProhibitLongChainsOfMethodCalls

Long chains of method calls indicate tightly coupled code. [Default severity 2]

ValuesAndExpressions::ProhibitMagicNumbers

Don't use values that don't explain themselves. [Default severity 2]

ValuesAndExpressions::ProhibitMismatchedOperators

Don't mix numeric operators with string operands, or vice−versa. [Default severity 3]

ValuesAndExpressions::ProhibitMixedBooleanOperators

Write " !$foo && $bar || $baz " instead of " not $foo && $bar or $baz". [Default severity 4]

ValuesAndExpressions::ProhibitNoisyQuotes

Use "q{}" or "qq{}" instead of quotes for awkward−looking strings. [Default severity 2]

ValuesAndExpressions::ProhibitQuotesAsQuotelikeOperatorDelimiters

Don't use quotes ("'", """, "`") as delimiters for the quote−like operators. [Default severity 3]

ValuesAndExpressions::ProhibitSpecialLiteralHeredocTerminator

Don't write " print <<'__END__' ". [Default severity 3]

ValuesAndExpressions::ProhibitVersionStrings

Don't use strings like "v1.4" or 1.4.5 when including other modules. [Default severity 3]

ValuesAndExpressions::RequireConstantVersion

Require $VERSION to be a constant rather than a computed value. [Default severity 2]

ValuesAndExpressions::RequireInterpolationOfMetachars

Warns that you might have used single quotes when you really wanted double−quotes. [Default severity 1]

ValuesAndExpressions::RequireNumberSeparators

Write " 141_234_397.0145 " instead of 141234397.0145 . [Default severity 2]

ValuesAndExpressions::RequireQuotedHeredocTerminator

Write " print <<'THE_END' " or " print <<"THE_END" ". [Default severity 3]

ValuesAndExpressions::RequireUpperCaseHeredocTerminator

Write " <<'THE_END'; " instead of " <<'theEnd'; ". [Default severity 2]

Variables::ProhibitAugmentedAssignmentInDeclaration

Do not write " my $foo .= 'bar'; ". [Default severity 4]

Variables::ProhibitConditionalDeclarations

Do not write " my $foo = $bar if $baz; ". [Default severity 5]

Variables::ProhibitEvilVariables

Ban variables that aren't blessed by your shop. [Default severity 5]

Variables::ProhibitLocalVars

Use "my" instead of "local", except when you have to. [Default severity 2]

Variables::ProhibitMatchVars

Avoid "$`", $&, "$'" and their English equivalents. [Default severity 4]

Variables::ProhibitPackageVars

Eliminate globals declared with "our" or "use vars". [Default severity 3]

Variables::ProhibitPerl4PackageNames

Use double colon (::) to separate package name components instead of single quotes ('). [Default severity 2]

Variables::ProhibitPunctuationVars

Write $EVAL_ERROR instead of $@. [Default severity 2]

Variables::ProhibitReusedNames

Do not reuse a variable name in a lexical scope [Default severity 3]

Variables::ProhibitUnusedVariables

Don't ask for storage you don't need. [Default severity 3]

Variables::ProtectPrivateVars

Prevent access to private vars in other packages. [Default severity 3]

Variables::RequireInitializationForLocalVars

Write "local $foo = $bar;" instead of just "local $foo;". [Default severity 3]

Variables::RequireLexicalLoopIterators

Write "for my $element (@list) {...}" instead of "for $element (@list) {...}". [Default severity 5]

Variables::RequireLocalizedPunctuationVars

Magic variables should be assigned as "local". [Default severity 4]

Variables::RequireNegativeIndices

Negative array index should be used. [Default severity 4]