NAME

Perl::ToPerl6 - Critique Perl source code for best-practices.

SYNOPSIS

    use Perl::ToPerl6;
    my $file = shift;
    my $mogrify = Perl::ToPerl6->new();
    my @transformations = $mogrify->transform($file);
    print @transformations;

DESCRIPTION

Perl::ToPerl6 is an extensible framework for creating and applying coding standards to Perl source code. Essentially, it is a static source code analysis engine. Perl::ToPerl6 is distributed with a number of Perl::ToPerl6::Transformer modules that attempt to enforce various coding guidelines. Most Transformer modules are based on Damian Conway's book Perl Best Practices. However, Perl::ToPerl6 is not limited to PBP and will even support Transformers that contradict Conway. You can enable, disable, and customize those Polices through the Perl::ToPerl6 interface. You can also create new Transformer modules that suit your own tastes.

For a command-line interface to Perl::ToPerl6, see the documentation for perlmogrify. If you want to integrate Perl::ToPerl6 with your build process, Test::Perl::ToPerl6 provides an interface that is suitable for test programs. Also, Test::Perl::ToPerl6::Progressive is useful for gradually applying coding standards to legacy code. For the ultimate convenience (at the expense of some flexibility) see the mogrification pragma.

If you'd like to try Perl::ToPerl6 without installing anything, there is a web-service available at http://perlmogrify.com. The web-service does not yet support all the configuration features that are available in the native Perl::ToPerl6 API, but it should give you a good idea of what it does.

Also, ActivePerl includes a very slick graphical interface to Perl-ToPerl6 called perlmogrify-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, -necessity => $N, -detail => $N, -theme => $string, -include => \@PATTERNS, -exclude => \@PATTERNS, -top => $N, -in_place => $B, -only => $B, -profile-strictness => $PROFILE_STRICTNESS_{WARN|FATAL|QUIET}, -force => $B, -verbose => $N ], -color => $B, -pager => $string, -mogrification-fatal => $B)
new()

Returns a reference to a new Perl::ToPerl6 object. Most arguments are just passed directly into Perl::ToPerl6::Config, but I have described them here as well. The default value for all arguments can be defined in your .perlmogrifyrc 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::ToPerl6::Config attempts to find a .perlmogrifyrc configuration file in the current directory, and then in your home directory. Alternatively, you can set the PERLMOGRIFY 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 Transformers will be loaded with their default configuration. See "CONFIGURATION" for more information.

-necessity is the minimum necessity level. Only Transformer modules that have a necessity greater than $N will be applied. Necessity values are integers ranging from 1 (least severe transformations) to 5 (most severe transformations). The default is 5. For a given -profile, decreasing the -necessity will usually reveal more Transformer transformations. You can set the default value for this option in your .perlmogrifyrc file. Users can redefine the necessity level for any Transformer in their .perlmogrifyrc file. See "CONFIGURATION" for more information.

If it is difficult for you to remember whether necessity "5" is the most or least restrictive level, then you can use one of these named values:

    NECESSITY NAME   ...is equivalent to...   NECESSITY NUMBER
    --------------------------------------------------------
    -necessity => 'gentle'                     -necessity => 5
    -necessity => 'stern'                      -necessity => 4
    -necessity => 'harsh'                      -necessity => 3
    -necessity => 'cruel'                      -necessity => 2
    -necessity => 'brutal'                     -necessity => 1

The names reflect how severely the code is mogrified: a gentle mogrification reports only the most severe transformations, and so on down to a brutal mogrification which reports even the most minor transformations.

-theme is special expression that determines which Transformers to apply based on their respective themes. For example, the following would load only Transformers that have a 'bugs' AND 'core' theme:

  my $mogrify = Perl::ToPerl6->new( -theme => 'bugs && core' );

Unless the -necessity option is explicitly given, setting -theme silently causes the -necessity to be set to 1. You can set the default value for this option in your .perlmogrifyrc file. See the "POLICY THEMES" section for more information about themes.

-include is a reference to a list of string @PATTERNS. Transformer modules that match at least one m/$PATTERN/ixms will always be loaded, irrespective of all other settings. For example:

    my $mogrify = Perl::ToPerl6->new(-include => ['layout'] -necessity => 4);

This would cause Perl::ToPerl6 to apply all the CodeLayout::* Transformer modules even though they have a necessity level that is less than 4. You can set the default value for this option in your .perlmogrifyrc file. You can also use -include in conjunction with the -exclude option. Note that -exclude takes precedence over -include when a Transformer matches both patterns.

-exclude is a reference to a list of string @PATTERNS. Transformer modules that match at least one m/$PATTERN/ixms will not be loaded, irrespective of all other settings. For example:

    my $mogrify = Perl::ToPerl6->new(-exclude => ['strict'] -necessity => 1);

This would cause Perl::ToPerl6 to not apply the RequireUseStrict and ProhibitNoStrict Transformer modules even though they have a necessity level that is greater than 1. You can set the default value for this option in your .perlmogrifyrc file. You can also use -exclude in conjunction with the -include option. Note that -exclude takes precedence over -include when a Transformer matches both patterns.

-single-transformer is a string PATTERN. Only one transformer that matches m/$PATTERN/ixms will be used. Transformers that do not match will be excluded. This option has precedence over the -necessity, -theme, -include, -exclude, and -only options. You can set the default value for this option in your .perlmogrifyrc file.

-top is the maximum number of Transformations to return when ranked by their necessity levels. This must be a positive integer. Transformations are still returned in the order that they occur within the file. Unless the -necessity option is explicitly given, setting -top silently causes the -necessity to be set to 1. You can set the default value for this option in your .perlmogrifyrc file.

-in_place is a boolean value. If set to a true value, Perl::ToPerl6 will replace the existing Perl source with its transformed equivalent. This of course overwrites the file's contents, and should be done sparingly, if at all. If set to a false value (which is the default), then Perl::ToPerl6 creates a new file, adding '.pl6' to the existing filename. You can set the default value for this option in your .perlmogrifyrc file.

-only is a boolean value. If set to a true value, Perl::ToPerl6 will only choose from Transformers that are mentioned in the user's profile. If set to a false value (which is the default), then Perl::ToPerl6 chooses from all the Transformers that it finds at your site. You can set the default value for this option in your .perlmogrifyrc file.

-profile-strictness is an enumerated value, one of "$PROFILE_STRICTNESS_WARN" in Perl::ToPerl6::Utils::Constants (the default), "$PROFILE_STRICTNESS_FATAL" in Perl::ToPerl6::Utils::Constants, and "$PROFILE_STRICTNESS_QUIET" in Perl::ToPerl6::Utils::Constants. If set to "$PROFILE_STRICTNESS_FATAL" in Perl::ToPerl6::Utils::Constants, Perl::ToPerl6 will make certain warnings about problems found in a .perlmogrifyrc or file specified via the -profile option fatal. For example, Perl::ToPerl6 normally only warns about profiles referring to non-existent Transformers, but this value makes this situation fatal. Correspondingly, "$PROFILE_STRICTNESS_QUIET" in Perl::ToPerl6::Utils::Constants makes Perl::ToPerl6 shut up about these things.

-detail can be an integer (from 0 to 5). If set to a non-zero value, all transformations of a necessity equal to or less than -detail will be reported on. You can set the default value for this option in your .perlmogrifyrc file.

-force is a boolean value that controls whether Perl::ToPerl6 observes the magical "## no mogrify" annotations in your code. If set to a true value, Perl::ToPerl6 will analyze all code. If set to a false value (which is the default) Perl::ToPerl6 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 .perlmogrifyrc file.

-verbose can be a positive integer (from 1 to 11), or a literal format specification. See Perl::ToPerl6::Transformation for an explanation of format specifications. You can set the default value for this option in your .perlmogrifyrc file.

-color and -pager are not used by Perl::ToPerl6 but is provided for the benefit of perlmogrify.

-mogrification-fatal is not used by Perl::ToPerl6 but is provided for the benefit of mogrification.

-color-necessity-highest, -color-necessity-high, -color-necessity- medium, -color-necessity-low, and -color-necessity-lowest are not used by Perl::ToPerl6, but are provided for the benefit of perlmogrify. Each is set to the Term::ANSIColor color specification to be used to display transformations of the corresponding necessity.

-files-with-transformations and -files-without-transformations are not used by Perl::ToPerl6, but are provided for the benefit of perlmogrify, to cause only the relevant filenames to be displayed.

METHODS

transform( $source_code )

Runs the $source_code through the Perl::ToPerl6 engine using all the Transformers 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::ToPerl6::Transformation objects for each transformation of the loaded Transformers. The list is sorted in the order that the Transformations appear in the code. If there are no transformations, this method returns an empty list.

apply_transform( -transformer => $transformer_name, -params => \%param_hash )

Creates a Transformer object and loads it into this ToPerl6. If the object cannot be instantiated, it will throw a fatal exception. Otherwise, it returns a reference to this ToPerl6.

-transformer is the name of a Perl::ToPerl6::Transformer subclass module. The 'Perl::ToPerl6::Transformer' portion of the name can be omitted for brevity. This argument is required.

-params is an optional reference to a hash of Transformer parameters. The contents of this hash reference will be passed into to the constructor of the Transformer module. See the documentation in the relevant Transformer module for a description of the arguments it supports.

transformers()

Returns a list containing references to all the Transformer objects that have been loaded into this engine. Objects will be in the order that they were loaded.

config()

Returns the Perl::ToPerl6::Config object that was created for or given to this ToPerl6.

statistics()

Returns the Perl::ToPerl6::Statistics object that was created for this ToPerl6. The Statistics object accumulates data for all files that are analyzed by this ToPerl6.

FUNCTIONAL INTERFACE

For those folks who prefer to have a functional interface, The transform 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::ToPerl6 object internally. The keys of that hash should be the same as those supported by the Perl::ToPerl6::new() method. Here are some examples:

    use Perl::ToPerl6 qw(transform);

    # Use default parameters...
    @transformations = transform( $some_file );

    # Use custom parameters...
    @transformations = transform( {-necessity => 2}, $some_file );

    # As a one-liner
    %> perl -MPerl::ToPerl6=transform -e 'print transform(shift)' some_file.pm

None of the other object-methods are currently supported as static functions. Sorry.

CONFIGURATION

Most of the settings for Perl::ToPerl6 and each of the Transformer modules can be controlled by a configuration file. The default configuration file is called .perlmogrifyrc. Perl::ToPerl6 will look for this file in the current directory first, and then in your home directory. Alternatively, you can set the PERLMOGRIFY 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::ToPerl6::Transformer 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::ToPerl6 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.

    necessity  = 3                                     #Integer or named level
    in_place   = 0                                     #Zero or One
    only       = 1                                     #Zero or One
    force      = 0                                     #Zero or One
    detail     = 0                                     #Integer or named level
    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
    mogrification-fatal = 1                            #Zero or One
    color               = 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::ToPerl6::Transformer::Category::TransformerName]
    necessity = 1
    set_themes = foo bar
    add_themes = baz
    arg1 = value1
    arg2 = value2

Perl::ToPerl6::Transformer::Category::TransformerName is the full name of a module that implements the transformer. The Transformer modules distributed with Perl::ToPerl6 have been grouped into categories according to token type. For brevity, you can omit the 'Perl::ToPerl6::Transformer' part of the module name.

necessity is the level of importance you wish to assign to the Transformer. All Transformer modules are defined with a default necessity value ranging from 1 (least severe) to 5 (most severe). However, you may disagree with the default necessity and choose to give it a higher or lower necessity, based on your own coding philosophy. You can set the necessity to an integer from 1 to 5, or use one of the equivalent names:

    NECESSITY NAME ...is equivalent to... NECESSITY NUMBER
    ----------------------------------------------------
    gentle                                             5
    stern                                              4
    harsh                                              3
    cruel                                              2
    brutal                                             1

The names reflect how severely the code is mogrified: a gentle mogrification reports only the most severe transformations, and so on down to a brutal mogrification which reports even the most minor transformations.

set_themes sets the theme for the Transformer 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 Transformer. The argument is a string of one or more whitespace-delimited words. Themes are case- insensitive. See "POLICY THEMES" for more information.

The remaining key-value pairs are configuration parameters that will be passed into the constructor for that Transformer. The constructors for most Transformer objects do not support arguments, and those that do should have reasonable defaults. See the documentation on the appropriate Transformer module for more details.

Instead of redefining the necessity for a given Transformer, you can completely disable a Transformer by prepending a '-' to the name of the module in your configuration file. In this manner, the Transformer will never be loaded, regardless of the -necessity given to the Perl::ToPerl6 constructor.

A simple configuration might look like this:

    #--------------------------------------------------------------
    # I think these are really important, so always load them

    [TestingAndDebugging::RequireUseStrict]
    necessity = 5

    [TestingAndDebugging::RequireUseWarnings]
    necessity = 5

    #--------------------------------------------------------------
    # I think these are less important, so only load when asked

    [Variables::ProhibitPackageVars]
    necessity = 2

    [ControlStructures::ProhibitPostfixControls]
    allow = if unless  # My custom configuration
    necessity = cruel   # Same as "necessity = 2"

    #--------------------------------------------------------------
    # Give these transformers a custom theme.  I can activate just
    # these transformers by saying `perlmogrify -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 Transformers, I accept the default necessity,
    # so no additional configuration is required for them.

For additional configuration examples, see the perlmogrifyrc file that is included in this examples directory of this distribution.

Damian Conway's own Perl::ToPerl6 configuration is also included in this distribution as examples/perlmogrifyrc-conway.

THE POLICIES

A large number of Transformer modules are distributed with Perl::ToPerl6. They are described briefly in the companion document Perl::ToPerl6::TransformerSummary and in more detail in the individual modules themselves. Say "perlmogrify -doc PATTERN" to see the perldoc for all Transformer modules that match the regex m/PATTERN/ixms

There are a number of distributions of additional transformers on CPAN. If Perl::ToPerl6 doesn't contain a transformer 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 Transformer is defined with one or more "themes". Themes can be used to create arbitrary groups of Transformers. They are intended to provide an alternative mechanism for selecting your preferred set of Transformers. For example, you may wish disable a certain subset of Transformers when analyzing test programs. Conversely, you may wish to enable only a specific subset of Transformers when analyzing modules.

The Transformers that ship with Perl::ToPerl6 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 transformers that ship with Perl::ToPerl6
    pbp               Transformers that come directly from "Perl Best Practices"
    bugs              Transformers that that prevent or reveal bugs
    maintenance       Transformers that affect the long-term health of the code
    cosmetic          Transformers that only have a superficial effect
    complexity        Transformers that specificaly relate to code complexity
    security          Transformers that relate to security issues
    tests             Transformers that are specific to test programs

Any Transformer may fit into multiple themes. Say "perlmogrify -list" to get a listing of all available Transformers and the themes that are associated with each one. You can also change the theme for any Transformer in your .perlmogrifyrc file. See the "CONFIGURATION" section for more information about that.

Using the -theme option, you can create an arbitrarily complex rule that determines which Transformers 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 Transformers.

BENDING THE RULES

Perl::ToPerl6 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::ToPerl6 to ignore certain lines or blocks of code by using annotations:

    require 'LegacyLibaray1.pl';  ## no mogrify
    require 'LegacyLibrary2.pl';  ## no mogrify

    for my $element (@list) {

        ## no mogrify

        $foo = "";               #Violates 'ProhibitEmptyQuotes'
        $barf = bar() if $foo;   #Violates 'ProhibitPostfixControls'
        #Some more evil code...

        ## use mogrify

        #Some good code...
        do_something($_);
    }

The "## no mogrify" annotations direct Perl::ToPerl6 to ignore the remaining lines of code until a "## use mogrify" annotation is found. If the "## no mogrify" annotation is on the same line as a code statement, then only that line of code is overlooked. To direct perlmogrify to ignore the "## no mogrify" annotations, use the --force option.

A bare "## no mogrify" annotation disables all the active Transformers. If you wish to disable only specific Transformers, add a list of Transformer names as arguments, just as you would for the "no strict" or "no warnings" pragmas. For example, this would disable the ProhibitEmptyQuotes and ProhibitPostfixControls transformers until the end of the block or until the next "## use mogrify" annotation (whichever comes first):

    ## no mogrify (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 Transformer names are matched against the "## no mogrify" arguments as regular expressions, you can abbreviate the Transformer names or disable an entire family of Transformers in one shot like this:

    ## no mogrify (NamingConventions)

    # Now exempt from NamingConventions::Capitalization
    my $camelHumpVar = 'foo';

    # Now exempt from NamingConventions::Capitalization
    sub camelHumpSub {}

The argument list must be enclosed in parentheses and must contain one or more comma-separated barewords (e.g. don't use quotes). The "## no mogrify" annotations can be nested, and Transformers named by an inner annotation will be disabled along with those already disabled an outer annotation.

Some Transformers like Subroutines::ProhibitExcessComplexity apply to an entire block of code. In those cases, the "## no mogrify" annotation must appear on the line where the transformation is reported. For example:

    sub complicated_function {  ## no mogrify (ProhibitExcessComplexity)
        # Your code here...
    }

Transformers such as Documentation::RequirePodSections apply to the entire document, in which case transformations are reported at line 1.

Use this feature wisely. "## no mogrify" 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 Transformers you want to disable (i.e. never use a bare "## no mogrify"). If Perl::ToPerl6 complains about your code, try and find a compliant solution before resorting to this feature.

THE Perl::ToPerl6 PHILOSOPHY

Coding standards are deeply personal and highly subjective. The goal of Perl::ToPerl6 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::ToPerl6 is merely a tool for encouraging consistency. If there is a transformer 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 transformers into Perl::ToPerl6.

EXTENDING THE MOGRIFIER

The modular design of Perl::ToPerl6 is intended to facilitate the addition of new Transformers. You'll need to have some understanding of PPI, but most Transformer modules are pretty straightforward and only require about 20 lines of code. Please see the Perl::ToPerl6::DEVELOPER file included in this distribution for a step-by-step demonstration of how to create new Transformer modules.

If you develop any Transformer modules, feel free to add a pull request on GitHub, http://github.com/drforr/Perl-Mogrify.git.

PREREQUISITES

Perl::ToPerl6 requires the following modules:

B::Keywords

Config::Tiny

Exception::Class

File::HomeDir

File::Spec

File::Spec::Unix

File::Which

IO::String

List::MoreUtils

List::Util

Module::Pluggable

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@perlmogrify.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://perlmogrify.tigris.org/servlets/SummarizeList?listName=users. At least one member of the development team is usually hanging around in irc://irc.perl.org/#perlmogrify and you can follow Perl::ToPerl6 on Twitter, at https://twitter.com/perlmogrify.

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::ToPerl6::Transformer, please submit them at "/github.com/Perl-ToPerl6 /Perl-ToPerl6/issues" in https:. Thanks.

CREDITS

Adam Kennedy - For creating PPI, the heart and soul of Perl::ToPerl6.

Chris Dolan - For contributing the best features and Transformer 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.

Thanks also to the Perl Foundation for providing a grant to support Chris Dolan's project to implement twenty PBP transformers. http://www.perlfoundation.org/april_1_2007_new_grant_awards

AUTHOR

Jeffrey Goff <drforr@pobox.com>

AUTHOR Emeritus

Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

Copyright (c) 2015 Jeffrey Goff. 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.