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.
RequireSomething
ProhibitSomething
perlcritic --profile-proto
Use List::MoreUtils::any instead of grep in boolean context. [Default severity 2]
List::MoreUtils::any
grep
Map blocks should have a single statement. [Default severity 3]
Use 4-argument substr instead of writing substr($foo, 2, 6) = $bar. [Default severity 3]
substr
substr($foo, 2, 6) = $bar
Forbid $b before $a in sort blocks. [Default severity 1]
Use Time::HiRes instead of something like select(undef, undef, undef, .05). [Default severity 5]
select(undef, undef, undef, .05)
Write eval { my $foo; bar($foo) } instead of eval "my $foo; bar($foo);". [Default severity 5]
eval { my $foo; bar($foo) }
eval "my $foo; bar($foo);"
Write split /-/, $string instead of split '-', $string. [Default severity 2]
split /-/, $string
split '-', $string
Write eval { $foo->can($name) } instead of UNIVERSAL::can($foo, $name). [Default severity 3]
eval { $foo->can($name) }
UNIVERSAL::can($foo, $name)
Write eval { $foo->isa($pkg) } instead of UNIVERSAL::isa($foo, $pkg). [Default severity 3]
eval { $foo->isa($pkg) }
UNIVERSAL::isa($foo, $pkg)
Don't pass $_ to built-in functions that assume it, or to most filetest operators. [Default severity 2]
Don't use grep in void contexts. [Default severity 3]
Don't use map in void contexts. [Default severity 3]
map
Write grep { /$pattern/ } @list instead of grep /$pattern/, @list. [Default severity 4]
grep { /$pattern/ } @list
grep /$pattern/, @list
Write map { /$pattern/ } @list instead of map /$pattern/, @list. [Default severity 4]
map { /$pattern/ } @list
map /$pattern/, @list
Use glob q{*} instead of <*>. [Default severity 5]
glob q{*}
Sort blocks should have a single statement. [Default severity 3]
AUTOLOAD methods should be avoided. [Default severity 3]
Employ use base instead of @ISA. [Default severity 3]
use base
@ISA
Write bless {}, $class; instead of just bless {};. [Default severity 5]
bless {}, $class;
bless {};
Use spaces instead of tabs. [Default severity 3]
Write open $handle, $path instead of open($handle, $path). [Default severity 1]
open $handle, $path
open($handle, $path)
Write qw(foo bar baz) instead of ('foo', 'bar', 'baz'). [Default severity 2]
qw(foo bar baz)
('foo', 'bar', 'baz')
Don't use whitespace at the end of lines. [Default severity 1]
Use the same newline through the source. [Default severity 4]
Must run code through perltidy. [Default severity 1]
Put a comma at the end of every multi-line list declaration, including the last one. [Default severity 1]
Write for(0..20) instead of for($i=0; $i<=20; $i++). [Default severity 2]
for(0..20)
for($i=0; $i<=20; $i++)
Don't write long "if-elsif-elsif-elsif-elsif...else" chains. [Default severity 3]
Don't write deeply nested loops and conditionals. [Default severity 3]
Don't use labels that are the same as the special block names. [Default severity 4]
Don't modify $_ in list functions. [Default severity 5]
$_
Don't use operators like not, !~, and le within until and unless. [Default severity 3]
not
!~
le
until
unless
Write if($condition){ do_something() } instead of do_something() if $condition. [Default severity 2]
if($condition){ do_something() }
do_something() if $condition
Write if(! $condition) instead of unless($condition). [Default severity 2]
if(! $condition)
unless($condition)
Don't write code after an unconditional die, exit, or next. [Default severity 4]
die, exit, or next
Write while(! $condition) instead of until($condition). [Default severity 2]
while(! $condition)
until($condition)
Never use ... in production code. [Default severity 4]
...
Check your spelling. [Default severity 1]
The =head1 NAME section should match the package. [Default severity 1]
=head1 NAME
All POD should be after __END__. [Default severity 1]
__END__
Provide text to display with your pod links. [Default severity 2]
Organize your POD into the customary sections. [Default severity 2]
Use functions from Carp instead of warn or die. [Default severity 3]
warn
die
You can't depend upon the value of $@/$EVAL_ERROR to tell whether an eval failed. [Default severity 3]
$@
$EVAL_ERROR
eval
Discourage stuff like @files = `ls $directory`. [Default severity 3]
@files = `ls $directory`
Write open my $fh, q{<}, $filename; instead of open FH, q{<}, $filename;. [Default severity 5]
open my $fh, q{<}, $filename;
open FH, q{<}, $filename;
Use "<>" or "<ARGV>" or a prompting module instead of "<STDIN>". [Default severity 4]
Use prompt() instead of -t. [Default severity 5]
Use local $/ = undef or Path::Tiny instead of joined readline. [Default severity 3]
local $/ = undef
Never write select($fh). [Default severity 4]
select($fh)
Write while( $line = <> ){...} instead of for(<>){...}. [Default severity 4]
while( $line = <> ){...}
for(<>){...}
Write open $fh, q{<}, $filename; instead of open $fh, "<$filename";. [Default severity 5]
open $fh, q{<}, $filename;
open $fh, "<$filename";
Write print {$FH} $foo, $bar; instead of print $FH $foo, $bar;. [Default severity 1]
print {$FH} $foo, $bar;
print $FH $foo, $bar;
Close filehandles as soon as possible after opening them. [Default severity 4]
Write my $error = close $fh; instead of close $fh;. [Default severity 2]
my $error = close $fh;
close $fh;
Write my $error = open $fh, $mode, $filename; instead of open $fh, $mode, $filename;. [Default severity 3]
my $error = open $fh, $mode, $filename;
open $fh, $mode, $filename;
Return value of flagged function ignored. [Default severity 1]
Write open $fh, q{<:encoding(UTF-8)}, $filename; instead of open $fh, q{<:utf8}, $filename;. [Default severity 5]
open $fh, q{<:encoding(UTF-8)}, $filename;
open $fh, q{<:utf8}, $filename;
Do not use format. [Default severity 3]
format
Do not use tie. [Default severity 2]
tie
Forbid a bare ## no critic [Default severity 3]
## no critic
Remove ineffective "## no critic" annotations. [Default severity 2]
Export symbols via @EXPORT_OK or %EXPORT_TAGS instead of @EXPORT. [Default severity 4]
@EXPORT_OK
%EXPORT_TAGS
@EXPORT
Avoid putting conditional logic around compile-time includes. [Default severity 3]
Ban modules that aren't blessed by your shop. [Default severity 5]
Minimize complexity in code that is outside of subroutines. [Default severity 3]
Put packages (especially subclasses) in separate files. [Default severity 4]
Write require Module instead of require 'Module.pm'. [Default severity 5]
require Module
require 'Module.pm'
End each module with an explicitly 1; instead of some funky expression. [Default severity 4]
1;
Always make the package explicit. [Default severity 4]
package
Package declaration must match filename. [Default severity 5]
use English must be passed a -no_match_vars argument. [Default severity 2]
use English
-no_match_vars
Give every module a $VERSION number. [Default severity 2]
$VERSION
Distinguish different program components by case. [Default severity 1]
Don't use vague variable or subroutine names like 'last' or 'record'. [Default severity 3]
Prohibit indirect object call syntax. [Default severity 4]
Write @{ $array_ref } instead of @$array_ref. [Default severity 2]
@{ $array_ref }
@$array_ref
Capture variable used outside conditional. [Default severity 3]
Split long regexps into smaller qr// chunks. [Default severity 3]
qr//
Use named character classes instead of explicit character lists. [Default severity 1]
Use character classes for literal meta-characters instead of escapes. [Default severity 1]
Use eq or hash instead of fixed-pattern regexps. [Default severity 2]
eq
Use [abc] instead of a|b|c. [Default severity 1]
[abc]
a|b|c
Only use a capturing group if you plan to use the captured value. [Default severity 3]
Use only // or {} to delimit regexps. [Default severity 1]
//
{}
Don't use $_ to match against regexes. [Default severity 2]
Use { and } to delimit multi-line regexps. [Default severity 1]
{
}
Always use the /s modifier with regular expressions. [Default severity 2]
/s
Always use the /x modifier with regular expressions. [Default severity 3]
/x
Always use the /m modifier with regular expressions. [Default severity 2]
/m
Don't call functions with a leading ampersand sigil. [Default severity 2]
Don't declare your own open function. [Default severity 4]
open
Minimize complexity by factoring code into smaller subroutines. [Default severity 3]
Return failure with bare return instead of return undef. [Default severity 5]
return
return undef
Too many arguments. [Default severity 3]
sub never { sub correct {} }. [Default severity 5]
sub never { sub correct {} }
Behavior of sort is not defined if called in scalar context. [Default severity 5]
sort
Don't write sub my_function (@@) {}. [Default severity 5]
sub my_function (@@) {}
Prevent unused private subroutines. [Default severity 3]
Prevent access to private subs in other packages. [Default severity 3]
Always unpack @_ first. [Default severity 4]
@_
End every path through a subroutine with an explicit return statement. [Default severity 4]
Prohibit various flavors of no strict. [Default severity 5]
no strict
Prohibit various flavors of no warnings. [Default severity 4]
no warnings
Don't turn off strict for large blocks of code. [Default severity 4]
Tests should all have labels. [Default severity 3]
Always use strict. [Default severity 5]
use strict
Always use warnings. [Default severity 4]
use warnings
Don't use the comma operator as a statement separator. [Default severity 4]
Prohibit version values from outside the module. [Default severity 3]
Don't use constant FOO => 15. [Default severity 4]
use constant FOO => 15
Write q{} instead of ''. [Default severity 2]
q{}
''
Write "\N{DELETE}" instead of "\x7F", etc. [Default severity 2]
"\N{DELETE}"
"\x7F"
Use concatenation or HEREDOCs instead of literal line breaks in strings. [Default severity 3]
Always use single quotes for literal strings. [Default severity 1]
Write oct(755) instead of 0755. [Default severity 5]
oct(755)
0755
Long chains of method calls indicate tightly coupled code. [Default severity 2]
Don't use values that don't explain themselves. [Default severity 2]
Don't mix numeric operators with string operands, or vice-versa. [Default severity 3]
Write !$foo && $bar || $baz instead of not $foo && $bar or $baz. [Default severity 4]
!$foo && $bar || $baz
not $foo && $bar or $baz
Use q{} or qq{} instead of quotes for awkward-looking strings. [Default severity 2]
qq{}
Don't use quotes (', ", `) as delimiters for the quote-like operators. [Default severity 3]
'
"
`
Don't write print <<'__END__' . [Default severity 3]
print <<'__END__'
Don't use strings like v1.4 or 1.4.5 when including other modules. [Default severity 3]
v1.4
1.4.5
Require $VERSION to be a constant rather than a computed value. [Default severity 2]
Warns that you might have used single quotes when you really wanted double-quotes. [Default severity 1]
Write 141_234_397.0145 instead of 141234397.0145 . [Default severity 2]
141_234_397.0145
141234397.0145
Write print <<'THE_END' or print <<"THE_END" . [Default severity 3]
print <<'THE_END'
print <<"THE_END"
Write <<'THE_END'; instead of <<'theEnd'; . [Default severity 2]
<<'THE_END';
<<'theEnd';
Do not write my $foo .= 'bar'; . [Default severity 4]
my $foo .= 'bar';
Do not write my $foo = $bar if $baz; . [Default severity 5]
my $foo = $bar if $baz;
Ban variables that aren't blessed by your shop. [Default severity 5]
Use my instead of local, except when you have to. [Default severity 2]
my
local
Avoid $`, $&, $' and their English equivalents. [Default severity 4]
$`
$&
$'
Eliminate globals declared with our or use vars. [Default severity 3]
our
use vars
Use double colon (::) to separate package name components instead of single quotes ('). [Default severity 2]
Write $EVAL_ERROR instead of $@. [Default severity 2]
Do not reuse a variable name in a lexical scope [Default severity 3]
Don't ask for storage you don't need. [Default severity 3]
Prevent access to private vars in other packages. [Default severity 3]
Write local $foo = $bar; instead of just local $foo;. [Default severity 3]
local $foo = $bar;
local $foo;
Write for my $element (@list) {...} instead of for $element (@list) {...}. [Default severity 5]
for my $element (@list) {...}
for $element (@list) {...}
Magic variables should be assigned as "local". [Default severity 4]
Negative array index should be used. [Default severity 4]
This is part of Perl::Critic version 1.126.
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved.
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.
To install Perl::Critic, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Perl::Critic
CPAN shell
perl -MCPAN -e shell install Perl::Critic
For more information on module installation, please visit the detailed CPAN module installation guide.