Provided by: libperl-critic-perl_1.126-1_all 
NAME
Perl::Critic - Critique Perl source code for best-practices.
SYNOPSIS
use Perl::Critic;
my $file = shift;
my $critic = Perl::Critic->new();
my @violations = $critic->critique($file);
print @violations;
DESCRIPTION
Perl::Critic is an extensible framework for creating and applying coding standards to Perl
source code. Essentially, it is a static source code analysis engine. Perl::Critic is
distributed with a number of Perl::Critic::Policy modules that attempt to enforce various
coding guidelines. Most Policy modules are based on Damian Conway's book Perl Best
Practices. However, Perl::Critic is not limited to PBP and will even support Policies
that contradict Conway. You can enable, disable, and customize those Polices through the
Perl::Critic interface. You can also create new Policy modules that suit your own tastes.
For a command-line interface to Perl::Critic, see the documentation for perlcritic. If
you want to integrate Perl::Critic with your build process, Test::Perl::Critic provides an
interface that is suitable for test programs. Also, Test::Perl::Critic::Progressive is
useful for gradually applying coding standards to legacy code. For the ultimate
convenience (at the expense of some flexibility) see the criticism pragma.
If you'd like to try Perl::Critic without installing anything, there is a web-service
available at <http://perlcritic.com>. The web-service does not yet support all the
configuration features that are available in the native Perl::Critic API, but it should
give you a good idea of what it does.
Also, ActivePerl includes a very slick graphical interface to Perl-Critic called
"perlcritic-gui". You can get a free community edition of ActivePerl from
<http://www.activestate.com>.
INTERFACE SUPPORT
This is considered to be a public class. Any changes to its interface will go through a
deprecation cycle.
CONSTRUCTOR
"new( [ -profile => $FILE, -severity => $N, -theme => $string, -include => \@PATTERNS,
-exclude => \@PATTERNS, -top => $N, -only => $B, -profile-strictness =>
$PROFILE_STRICTNESS_{WARN|FATAL|QUIET}, -force => $B, -verbose => $N ], -color => $B,
-pager => $string, -allow-unsafe => $B, -criticism-fatal => $B)"
"new()"
Returns a reference to a new Perl::Critic object. Most arguments are just passed
directly into Perl::Critic::Config, but I have described them here as well. The
default value for all arguments can be defined in your .perlcriticrc file. See the
"CONFIGURATION" section for more information about that. All arguments are optional
key-value pairs as follows:
-profile is a path to a configuration file. If $FILE is not defined,
Perl::Critic::Config attempts to find a .perlcriticrc configuration file in the
current directory, and then in your home directory. Alternatively, you can set the
"PERLCRITIC" environment variable to point to a file in another location. If a
configuration file can't be found, or if $FILE is an empty string, then all Policies
will be loaded with their default configuration. See "CONFIGURATION" for more
information.
-severity is the minimum severity level. Only Policy modules that have a severity
greater than $N will be applied. Severity values are integers ranging from 1 (least
severe violations) to 5 (most severe violations). The default is 5. For a given
"-profile", decreasing the "-severity" will usually reveal more Policy violations. You
can set the default value for this option in your .perlcriticrc file. Users can
redefine the severity level for any Policy in their .perlcriticrc file. See
"CONFIGURATION" for more information.
If it is difficult for you to remember whether severity "5" is the most or least
restrictive level, then you can use one of these named values:
SEVERITY NAME ...is equivalent to... SEVERITY NUMBER
--------------------------------------------------------
-severity => 'gentle' -severity => 5
-severity => 'stern' -severity => 4
-severity => 'harsh' -severity => 3
-severity => 'cruel' -severity => 2
-severity => 'brutal' -severity => 1
The names reflect how severely the code is criticized: a "gentle" criticism reports
only the most severe violations, and so on down to a "brutal" criticism which reports
even the most minor violations.
-theme is special expression that determines which Policies to apply based on their
respective themes. For example, the following would load only Policies that have a
'bugs' AND 'pbp' theme:
my $critic = Perl::Critic->new( -theme => 'bugs && pbp' );
Unless the "-severity" option is explicitly given, setting "-theme" silently causes
the "-severity" to be set to 1. You can set the default value for this option in your
.perlcriticrc file. See the "POLICY THEMES" section for more information about
themes.
-include is a reference to a list of string @PATTERNS. Policy modules that match at
least one "m/$PATTERN/ixms" will always be loaded, irrespective of all other settings.
For example:
my $critic = Perl::Critic->new(-include => ['layout'] -severity => 4);
This would cause Perl::Critic to apply all the "CodeLayout::*" Policy modules even
though they have a severity level that is less than 4. You can set the default value
for this option in your .perlcriticrc file. You can also use "-include" in
conjunction with the "-exclude" option. Note that "-exclude" takes precedence over
"-include" when a Policy matches both patterns.
-exclude is a reference to a list of string @PATTERNS. Policy modules that match at
least one "m/$PATTERN/ixms" will not be loaded, irrespective of all other settings.
For example:
my $critic = Perl::Critic->new(-exclude => ['strict'] -severity => 1);
This would cause Perl::Critic to not apply the "RequireUseStrict" and
"ProhibitNoStrict" Policy modules even though they have a severity level that is
greater than 1. You can set the default value for this option in your .perlcriticrc
file. You can also use "-exclude" in conjunction with the "-include" option. Note
that "-exclude" takes precedence over "-include" when a Policy matches both patterns.
-single-policy is a string "PATTERN". Only one policy that matches "m/$PATTERN/ixms"
will be used. Policies that do not match will be excluded. This option has
precedence over the "-severity", "-theme", "-include", "-exclude", and "-only"
options. You can set the default value for this option in your .perlcriticrc file.
-top is the maximum number of Violations to return when ranked by their severity
levels. This must be a positive integer. Violations are still returned in the order
that they occur within the file. Unless the "-severity" option is explicitly given,
setting "-top" silently causes the "-severity" to be set to 1. You can set the
default value for this option in your .perlcriticrc file.
-only is a boolean value. If set to a true value, Perl::Critic will only choose from
Policies that are mentioned in the user's profile. If set to a false value (which is
the default), then Perl::Critic chooses from all the Policies that it finds at your
site. You can set the default value for this option in your .perlcriticrc file.
-profile-strictness is an enumerated value, one of "$PROFILE_STRICTNESS_WARN" in
Perl::Critic::Utils::Constants (the default), "$PROFILE_STRICTNESS_FATAL" in
Perl::Critic::Utils::Constants, and "$PROFILE_STRICTNESS_QUIET" in
Perl::Critic::Utils::Constants. If set to "$PROFILE_STRICTNESS_FATAL" in
Perl::Critic::Utils::Constants, Perl::Critic will make certain warnings about problems
found in a .perlcriticrc or file specified via the -profile option fatal. For example,
Perl::Critic normally only "warn"s about profiles referring to non-existent Policies,
but this value makes this situation fatal. Correspondingly,
"$PROFILE_STRICTNESS_QUIET" in Perl::Critic::Utils::Constants makes Perl::Critic shut
up about these things.
-force is a boolean value that controls whether Perl::Critic observes the magical "##
no critic" annotations in your code. If set to a true value, Perl::Critic will analyze
all code. If set to a false value (which is the default) Perl::Critic will ignore
code that is tagged with these annotations. See "BENDING THE RULES" for more
information. You can set the default value for this option in your .perlcriticrc
file.
-verbose can be a positive integer (from 1 to 11), or a literal format specification.
See Perl::Critic::Violation for an explanation of format specifications. You can set
the default value for this option in your .perlcriticrc file.
-unsafe directs Perl::Critic to allow the use of Policies that are marked as "unsafe"
by the author. Such policies may compile untrusted code or do other nefarious things.
-color and -pager are not used by Perl::Critic but is provided for the benefit of
perlcritic.
-criticism-fatal is not used by Perl::Critic but is provided for the benefit of
criticism.
-color-severity-highest, -color-severity-high, -color-severity- medium,
-color-severity-low, and -color-severity-lowest are not used by Perl::Critic, but are
provided for the benefit of perlcritic. Each is set to the Term::ANSIColor color
specification to be used to display violations of the corresponding severity.
-files-with-violations and -files-without-violations are not used by Perl::Critic, but
are provided for the benefit of perlcritic, to cause only the relevant filenames to be
displayed.
METHODS
"critique( $source_code )"
Runs the $source_code through the Perl::Critic engine using all the Policies that have
been loaded into this engine. If $source_code is a scalar reference, then it is
treated as a string of actual Perl code. If $source_code is a reference to an
instance of PPI::Document, then that instance is used directly. Otherwise, it is
treated as a path to a local file containing Perl code. This method returns a list of
Perl::Critic::Violation objects for each violation of the loaded Policies. The list
is sorted in the order that the Violations appear in the code. If there are no
violations, this method returns an empty list.
"add_policy( -policy => $policy_name, -params => \%param_hash )"
Creates a Policy object and loads it into this Critic. If the object cannot be
instantiated, it will throw a fatal exception. Otherwise, it returns a reference to
this Critic.
-policy is the name of a Perl::Critic::Policy subclass module. The
'Perl::Critic::Policy' portion of the name can be omitted for brevity. This argument
is required.
-params is an optional reference to a hash of Policy parameters. The contents of this
hash reference will be passed into to the constructor of the Policy module. See the
documentation in the relevant Policy module for a description of the arguments it
supports.
" policies() "
Returns a list containing references to all the Policy objects that have been loaded
into this engine. Objects will be in the order that they were loaded.
" config() "
Returns the Perl::Critic::Config object that was created for or given to this Critic.
" statistics() "
Returns the Perl::Critic::Statistics object that was created for this Critic. The
Statistics object accumulates data for all files that are analyzed by this Critic.
FUNCTIONAL INTERFACE
For those folks who prefer to have a functional interface, The "critique" method can be
exported on request and called as a static function. If the first argument is a hashref,
its contents are used to construct a new Perl::Critic object internally. The keys of that
hash should be the same as those supported by the "Perl::Critic::new()" method. Here are
some examples:
use Perl::Critic qw(critique);
# Use default parameters...
@violations = critique( $some_file );
# Use custom parameters...
@violations = critique( {-severity => 2}, $some_file );
# As a one-liner
%> perl -MPerl::Critic=critique -e 'print critique(shift)' some_file.pm
None of the other object-methods are currently supported as static functions. Sorry.
CONFIGURATION
Most of the settings for Perl::Critic and each of the Policy modules can be controlled by
a configuration file. The default configuration file is called .perlcriticrc.
Perl::Critic will look for this file in the current directory first, and then in your home
directory. Alternatively, you can set the "PERLCRITIC" environment variable to explicitly
point to a different file in another location. If none of these files exist, and the
"-profile" option is not given to the constructor, then all the modules that are found in
the Perl::Critic::Policy namespace will be loaded with their default configuration.
The format of the configuration file is a series of INI-style blocks that contain key-
value pairs separated by '='. Comments should start with '#' and can be placed on a
separate line or after the name-value pairs if you desire.
Default settings for Perl::Critic itself can be set before the first named block. For
example, putting any or all of these at the top of your configuration file will set the
default value for the corresponding constructor argument.
severity = 3 #Integer or named level
only = 1 #Zero or One
force = 0 #Zero or One
verbose = 4 #Integer or format spec
top = 50 #A positive integer
theme = (pbp || security) && bugs #A theme expression
include = NamingConventions ClassHierarchies #Space-delimited list
exclude = Variables Modules::RequirePackage #Space-delimited list
criticism-fatal = 1 #Zero or One
color = 1 #Zero or One
allow-unsafe = 1 #Zero or One
pager = less #pager to pipe output to
The remainder of the configuration file is a series of blocks like this:
[Perl::Critic::Policy::Category::PolicyName]
severity = 1
set_themes = foo bar
add_themes = baz
maximum_violations_per_document = 57
arg1 = value1
arg2 = value2
"Perl::Critic::Policy::Category::PolicyName" is the full name of a module that implements
the policy. The Policy modules distributed with Perl::Critic have been grouped into
categories according to the table of contents in Damian Conway's book Perl Best Practices.
For brevity, you can omit the 'Perl::Critic::Policy' part of the module name.
"severity" is the level of importance you wish to assign to the Policy. All Policy
modules are defined with a default severity value ranging from 1 (least severe) to 5 (most
severe). However, you may disagree with the default severity and choose to give it a
higher or lower severity, based on your own coding philosophy. You can set the "severity"
to an integer from 1 to 5, or use one of the equivalent names:
SEVERITY NAME ...is equivalent to... SEVERITY NUMBER
----------------------------------------------------
gentle 5
stern 4
harsh 3
cruel 2
brutal 1
The names reflect how severely the code is criticized: a "gentle" criticism reports only
the most severe violations, and so on down to a "brutal" criticism which reports even the
most minor violations.
"set_themes" sets the theme for the Policy and overrides its default theme. The argument
is a string of one or more whitespace-delimited alphanumeric words. Themes are case-
insensitive. See "POLICY THEMES" for more information.
"add_themes" appends to the default themes for this Policy. The argument is a string of
one or more whitespace-delimited words. Themes are case- insensitive. See "POLICY THEMES"
for more information.
"maximum_violations_per_document" limits the number of Violations the Policy will return
for a given document. Some Policies have a default limit; see the documentation for the
individual Policies to see whether there is one. To force a Policy to not have a limit,
specify "no_limit" or the empty string for the value of this parameter.
The remaining key-value pairs are configuration parameters that will be passed into the
constructor for that Policy. The constructors for most Policy objects do not support
arguments, and those that do should have reasonable defaults. See the documentation on
the appropriate Policy module for more details.
Instead of redefining the severity for a given Policy, you can completely disable a Policy
by prepending a '-' to the name of the module in your configuration file. In this manner,
the Policy will never be loaded, regardless of the "-severity" given to the Perl::Critic
constructor.
A simple configuration might look like this:
#--------------------------------------------------------------
# I think these are really important, so always load them
[TestingAndDebugging::RequireUseStrict]
severity = 5
[TestingAndDebugging::RequireUseWarnings]
severity = 5
#--------------------------------------------------------------
# I think these are less important, so only load when asked
[Variables::ProhibitPackageVars]
severity = 2
[ControlStructures::ProhibitPostfixControls]
allow = if unless # My custom configuration
severity = cruel # Same as "severity = 2"
#--------------------------------------------------------------
# Give these policies a custom theme. I can activate just
# these policies by saying `perlcritic -theme larry`
[Modules::RequireFilenameMatchesPackage]
add_themes = larry
[TestingAndDebugging::RequireTestLables]
add_themes = larry curly moe
#--------------------------------------------------------------
# I do not agree with these at all, so never load them
[-NamingConventions::Capitalization]
[-ValuesAndExpressions::ProhibitMagicNumbers]
#--------------------------------------------------------------
# For all other Policies, I accept the default severity,
# so no additional configuration is required for them.
For additional configuration examples, see the perlcriticrc file that is included in this
examples directory of this distribution.
Damian Conway's own Perl::Critic configuration is also included in this distribution as
examples/perlcriticrc-conway.
THE POLICIES
A large number of Policy modules are distributed with Perl::Critic. They are described
briefly in the companion document Perl::Critic::PolicySummary and in more detail in the
individual modules themselves. Say "perlcritic -doc PATTERN" to see the perldoc for all
Policy modules that match the regex "m/PATTERN/ixms"
There are a number of distributions of additional policies on CPAN. If Perl::Critic
doesn't contain a policy that you want, some one may have already written it. See the
"SEE ALSO" section below for a list of some of these distributions.
POLICY THEMES
Each Policy is defined with one or more "themes". Themes can be used to create arbitrary
groups of Policies. They are intended to provide an alternative mechanism for selecting
your preferred set of Policies. For example, you may wish disable a certain subset of
Policies when analyzing test programs. Conversely, you may wish to enable only a specific
subset of Policies when analyzing modules.
The Policies that ship with Perl::Critic have been broken into the following themes. This
is just our attempt to provide some basic logical groupings. You are free to invent new
themes that suit your needs.
THEME DESCRIPTION
--------------------------------------------------------------------------
core All policies that ship with Perl::Critic
pbp Policies that come directly from "Perl Best Practices"
bugs Policies that that prevent or reveal bugs
certrec Policies that CERT recommends
certrule Policies that CERT considers rules
maintenance Policies that affect the long-term health of the code
cosmetic Policies that only have a superficial effect
complexity Policies that specificaly relate to code complexity
security Policies that relate to security issues
tests Policies that are specific to test programs
Any Policy may fit into multiple themes. Say "perlcritic -list" to get a listing of all
available Policies and the themes that are associated with each one. You can also change
the theme for any Policy in your .perlcriticrc file. See the "CONFIGURATION" section for
more information about that.
Using the "-theme" option, you can create an arbitrarily complex rule that determines
which Policies will be loaded. Precedence is the same as regular Perl code, and you can
use parentheses to enforce precedence as well. Supported operators are:
Operator Alternative Example
-----------------------------------------------------------------
&& and 'pbp && core'
|| or 'pbp || (bugs && security)'
! not 'pbp && ! (portability || complexity)'
Theme names are case-insensitive. If the "-theme" is set to an empty string, then it
evaluates as true all Policies.
BENDING THE RULES
Perl::Critic takes a hard-line approach to your code: either you comply or you don't. In
the real world, it is not always practical (nor even possible) to fully comply with coding
standards. In such cases, it is wise to show that you are knowingly violating the
standards and that you have a Damn Good Reason (DGR) for doing so.
To help with those situations, you can direct Perl::Critic to ignore certain lines or
blocks of code by using annotations:
require 'LegacyLibaray1.pl'; ## no critic
require 'LegacyLibrary2.pl'; ## no critic
for my $element (@list) {
## no critic
$foo = ""; #Violates 'ProhibitEmptyQuotes'
$barf = bar() if $foo; #Violates 'ProhibitPostfixControls'
#Some more evil code...
## use critic
#Some good code...
do_something($_);
}
The "## no critic" annotations direct Perl::Critic to ignore the remaining lines of code
until a "## use critic" annotation is found. If the "## no critic" annotation is on the
same line as a code statement, then only that line of code is overlooked. To direct
perlcritic to ignore the "## no critic" annotations, use the "--force" option.
A bare "## no critic" annotation disables all the active Policies. If you wish to disable
only specific Policies, add a list of Policy names as arguments, just as you would for the
"no strict" or "no warnings" pragmas. For example, this would disable the
"ProhibitEmptyQuotes" and "ProhibitPostfixControls" policies until the end of the block or
until the next "## use critic" annotation (whichever comes first):
## no critic (EmptyQuotes, PostfixControls)
# Now exempt from ValuesAndExpressions::ProhibitEmptyQuotes
$foo = "";
# Now exempt ControlStructures::ProhibitPostfixControls
$barf = bar() if $foo;
# Still subjected to ValuesAndExpression::RequireNumberSeparators
$long_int = 10000000000;
Since the Policy names are matched against the "## no critic" arguments as regular
expressions, you can abbreviate the Policy names or disable an entire family of Policies
in one shot like this:
## no critic (NamingConventions)
# Now exempt from NamingConventions::Capitalization
my $camelHumpVar = 'foo';
# Now exempt from NamingConventions::Capitalization
sub camelHumpSub {}
The argument list must be enclosed in parentheses or brackets and must contain one or more
comma-separated barewords (e.g. don't use quotes). The "## no critic" annotations can be
nested, and Policies named by an inner annotation will be disabled along with those
already disabled an outer annotation.
Some Policies like "Subroutines::ProhibitExcessComplexity" apply to an entire block of
code. In those cases, the "## no critic" annotation must appear on the line where the
violation is reported. For example:
sub complicated_function { ## no critic (ProhibitExcessComplexity)
# Your code here...
}
Policies such as "Documentation::RequirePodSections" apply to the entire document, in
which case violations are reported at line 1.
Use this feature wisely. "## no critic" annotations should be used in the smallest
possible scope, or only on individual lines of code. And you should always be as specific
as possible about which Policies you want to disable (i.e. never use a bare "## no
critic"). If Perl::Critic complains about your code, try and find a compliant solution
before resorting to this feature.
THE Perl::Critic PHILOSOPHY
Coding standards are deeply personal and highly subjective. The goal of Perl::Critic is
to help you write code that conforms with a set of best practices. Our primary goal is
not to dictate what those practices are, but rather, to implement the practices discovered
by others. Ultimately, you make the rules -- Perl::Critic is merely a tool for
encouraging consistency. If there is a policy that you think is important or that we have
overlooked, we would be very grateful for contributions, or you can simply load your own
private set of policies into Perl::Critic.
EXTENDING THE CRITIC
The modular design of Perl::Critic is intended to facilitate the addition of new Policies.
You'll need to have some understanding of PPI, but most Policy modules are pretty
straightforward and only require about 20 lines of code. Please see the
Perl::Critic::DEVELOPER file included in this distribution for a step-by-step
demonstration of how to create new Policy modules.
If you develop any new Policy modules, feel free to send them to "<team@perlcritic.com>"
and I'll be happy to consider putting them into the Perl::Critic distribution. Or if you
would like to work on the Perl::Critic project directly, you can fork our repository at
"/github.com/Perl- Critic/Perl- Critic.git" in http:.
The Perl::Critic team is also available for hire. If your organization has its own coding
standards, we can create custom Policies to enforce your local guidelines. Or if your
code base is prone to a particular defect pattern, we can design Policies that will help
you catch those costly defects before they go into production. To discuss your needs with
the Perl::Critic team, just contact "<team@perlcritic.com>".
PREREQUISITES
Perl::Critic requires the following modules:
B::Keywords
Config::Tiny
Email::Address
Exception::Class
File::HomeDir
File::Spec
File::Spec::Unix
File::Which
IO::String
List::MoreUtils
List::Util
Module::Pluggable
Perl::Tidy
Pod::Spell
PPI
Pod::PlainText
Pod::Select
Pod::Usage
Readonly
Scalar::Util
String::Format
Task::Weaken
Term::ANSIColor
Text::ParseWords
version
CONTACTING THE DEVELOPMENT TEAM
You are encouraged to subscribe to the mailing list; send a message to
<mailto:users-subscribe@perlcritic.tigris.org>. To prevent spam, you may be required to
register for a user account with Tigris.org before being allowed to post messages to the
mailing list. See also the mailing list archives at
<http://perlcritic.tigris.org/servlets/SummarizeList?listName=users>. At least one member
of the development team is usually hanging around in <irc://irc.perl.org/#perlcritic> and
you can follow Perl::Critic on Twitter, at <https://twitter.com/perlcritic>.
SEE ALSO
There are a number of distributions of additional Policies available. A few are listed
here:
Perl::Critic::More
Perl::Critic::Bangs
Perl::Critic::Lax
Perl::Critic::StricterSubs
Perl::Critic::Swift
Perl::Critic::Tics
These distributions enable you to use Perl::Critic in your unit tests:
Test::Perl::Critic
Test::Perl::Critic::Progressive
There is also a distribution that will install all the Perl::Critic related modules known
to the development team:
Task::Perl::Critic
BUGS
Scrutinizing Perl code is hard for humans, let alone machines. If you find any bugs,
particularly false-positives or false-negatives from a Perl::Critic::Policy, please submit
them at "/github.com/Perl-Critic /Perl-Critic/issues" in https:. Thanks.
CREDITS
Adam Kennedy - For creating PPI, the heart and soul of Perl::Critic.
Damian Conway - For writing Perl Best Practices, finally :)
Chris Dolan - For contributing the best features and Policy modules.
Andy Lester - Wise sage and master of all-things-testing.
Elliot Shank - The self-proclaimed quality freak.
Giuseppe Maxia - For all the great ideas and positive encouragement.
and Sharon, my wife - For putting up with my all-night code sessions.
Thanks also to the Perl Foundation for providing a grant to support Chris Dolan's project
to implement twenty PBP policies.
<http://www.perlfoundation.org/april_1_2007_new_grant_awards>
AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
COPYRIGHT
Copyright (c) 2005-2013 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.