NAME

Perl::Critic - Engine to critique Perl souce code

SYNOPSIS

  use Perl::Critic;

  #Create Critic and load Policies from default config file
  $critic = Perl::Critic->new();

  #Create Critic and load only the most important Polices
  $critic = Perl::Critic->new(-priority => 1);

  #Create Critic and load Policies from specific config file
  $critic = Perl::Critic->new(-profile => $file);

  #Create Critic and load Policy by hand
  $critic = Perl::Critic->new(-profile => '');
  $critic->add_policy('MyPolicyModule');

  #Analyze code for policy violations
  @violations = $critic->critique($source_code);

DESCRIPTION

Perl::Critic is an extensible framework for creating and applying coding standards to Perl source code. It is, essentially, an automated code review. Perl::Critic is distributed with a number of Perl::Critic::Policy modules that enforce the guidelines in Damian Conway's book Perl Best Practices. You can choose and customize those Polices through the Perl::Critic interface. You can also create new and use new Policy modules that suit your own tastes.

For a convenient command-line interface to Perl::Critic, see the documentation for perlcritic.

CONSTRUCTOR

new( [ -profile => $FILE, -priority => $N ] )

Returns a reference to a Perl::Critic object. All arguments are optional key-value pairs.

-profile is the path to a configuration file that dictates which policies should be loaded into the Perl::Critic engine and how to configure each one. If $FILE is not defined, Perl::Critic attempts to find a .perlcriticrc configuration file in several places. If a configuration file can't be found, or if $FILE is an empty string, then Perl::Critic reverts to its factory setup and all Policy modules that are distributed with Perl::Critic will be loaded. See "CONFIGURATION" for more information.

-priority is the maximum priority value of Policies that should be loaded. 1 is the "highest" priority, and all numbers larger than 1 have "lower" priority. Only Policies that have been configured with a priority value less than or equal to $N will not be loaded into the engine. For a given -profile, increasing $N will result in more violations. See "CONFIGURATION" for more information.

METHODS

add_policy( -policy => $STRING [, -config => \%HASH ] )

Loads a Policy into this Critic engine. The engine will attmept to require the module named by $STRING and instantiate it. If the module fails to load or cannot be instantiated, it will throw a warning and return a false value. Otherwise, it returns a reference to this Critic engine.

-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.

-config is an optional reference to a hash of Policy configuration 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.

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 string of actual Perl code. Otherwise, it is treated as a path to a file of Perl code. Returns a list of Perl::Critic::Violation objects for each violation of the loaded Policies. If there are no violations, returns an empty list.

CONFIGURATION

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 configuration file in another location. If none of these files exist, and the -profile option is not given to the constructor, Perl::Critic defaults to its factory setup, which means that all the policies that are distributed with Perl::Critic will be loaded.

The format of the configuration file is a series of named sections that contain key-value pairs separated by ':' or '='. Comments should start with '#' and can be placed on a separate line or after the name-value pairs if you desire. The general recipe is a series of blocks like this:

    [Perl::Critic::Policy::Category::PolicyName]
    priority = 1
    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 ommit the 'Perl::Critic::Policy' part of the module name. The module must be a subclass of Perl::Critic::Policy.

priority is the level of importance you wish to assign to this policy. 1 is the "highest" priority level, and all numbers greater than 1 have increasingly "lower" priority. Only those policies with a priority less than or equal to the -priority value given to the Perl::Critic constructor will be loaded. The priority can be an arbitrarily large positive integer. If the priority is not defined, it defaults to 1.

The remaining key-value pairs are configuration parameters for that specific Policy and will be passed into the constructor of the Perl::Critic::Policy subclass. The constructors for most Policy modules do not support arguments, and those that do should have reasonable defaults. See the documentation on the appropriate Policy module for more details.

By default, all the policies that are distributed with Perl::Critic are loaded. Rather than assign priority levels to each one, you can simply "turn off" a Policy by prepending a '-' to the name of the module in the config file. In this manner, the Policy will never be loaded, regardless of the -priority given to the Perl::Critic constructor.

A simple configuration might look like this:

    #--------------------------------------------------------------
    # These are really important, so always load them

    [TestingAndDebugging::RequirePackageStricture]
    priority = 1

    [TestingAndDebugging::RequirePackageWarnings]
    priority = 1

    #--------------------------------------------------------------
    # These are less important, so only load when asked

    [Variables::ProhibitPackageVars]
    priority = 2

    [ControlStructures::ProhibitPostfixControls]
    priority = 2

    #--------------------------------------------------------------
    # I don't agree with these, so never load them

    [-NamingConventions::ProhibitMixedCaseVars]
    [-NamingConventions::ProhibitMixedCaseSubs]

THE POLICIES

The following Policy modules are distributed with Perl::Critic. 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. See the documentation of each module for it's specific details.

Perl::Critic::Policy::BuiltinFunctions::ProhibitStringyEval

Perl::Critic::Policy::BuiltinFunctions::RequireBlockGrep

Perl::Critic::Policy::BuiltinFunctions::RequireBlockMap

Perl::Critic::Policy::CodeLayout::ProhibitParensWithBuiltins

Perl::Critic::Policy::CodeLayout::RequireTidyCode

Perl::Critic::Policy::ControlStructures::ProhibitCascadingIfElse

Perl::Critic::Policy::ControlStructures::ProhibitPostfixControls

Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators

Perl::Critic::Policy::Modules::ProhibitMultiplePackages

Perl::Critic::Policy::Modules::ProhibitRequireStatements

Perl::Critic::Policy::Modules::ProhibitSpecificModules

Perl::Critic::Policy::Modules::ProhibitUnpackagedCode

Perl::Critic::Policy::NamingConventions::ProhibitMixedCaseSubs

Perl::Critic::Policy::NamingConventions::ProhibitMixedCaseVars

Perl::Critic::Policy::Subroutines::ProhibitBuiltinHomonyms

Perl::Critic::Policy::Subroutines::ProhibitExplicitReturnUndef

Perl::Critic::Policy::Subroutines::ProhibitSubroutinePrototypes

Perl::Critic::Policy::TestingAndDebugging::RequirePackageStricture

Perl::Critic::Policy::TestingAndDebugging::RequirePackageWarnings

Perl::Critic::Policy::ValuesAndExpressions::ProhibitConstantPragma

Perl::Critic::Policy::ValuesAndExpressions::ProhibitEmptyQuotes

Perl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals

Perl::Critic::Policy::ValuesAndExpressions::ProhibitLeadingZeros

Perl::Critic::Policy::ValuesAndExpressions::ProhibitNoisyQuotes

Perl::Critic::Policy::ValuesAndExpressions::RequireInterpolationOfMetachars

Perl::Critic::Policy::ValuesAndExpressions::RequireNumberSeparators

Perl::Critic::Policy::ValuesAndExpressions::RequireQuotedHeredocTerminator

Perl::Critic::Policy::ValuesAndExpressions::RequireUpperCaseHeredocTerminator

Perl::Critic::Policy::Variables::ProhibitLocalVars

Perl::Critic::Policy::Variables::ProhibitPackageVars

Perl::Critic::Policy::Variables::ProhibitPunctuationVars

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 to http://rt.cpan.org. Thanks.

CREDITS

Adam Kennedy - For creating PPI, the heart and soul of Perl::Critic.

Damian Conway - For writing Perl Best Practices

Sharon, my wife - For putting up with my all-night code sessions

AUTHOR

Jeffrey Ryan Thalhammer <thaljef@cpan.org>

COPYRIGHT

Copyright (c) 2005 Jeffrey Ryan Thalhammer. 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.

cpanm Perl::Critic

perl -MCPAN -e shell
install Perl::Critic