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/ perlmogrify

NAME

perlmogrify - Command-line interface to transform Perl source.

SYNOPSIS

  perlmogrify [-12345 | --brutal | --cruel | --harsh | --stern | --gentle]
              [--severity number | name] [{-p | --profile} file | --noprofile]
              [--top [ number ]] [--theme expression] [--include pattern]
              [--exclude pattern] [{-s | --single-policy} pattern]
              [--only | --noonly] [--profile-strictness {warn|fatal|quiet}]
              [--force | --noforce] [--statistics] [--statistics-only]
              [--count | -C] [--verbose {number | format}] [--allow-unsafe]
              [--color | --nocolor] [--pager pager] [--quiet]
              [--color-severity-highest color_specification]
              [--color-severity-high color_specification]
              [--color-severity-medium color_specification]
              [--color-severity-low color_specification]
              [--color-severity-lowest color_specification]
              [--files-with-transformations | -l]
              [--files-without-transformations | -L]
              [--program-extensions file_name_extension]
              {FILE | DIRECTORY | STDIN}

  perlmogrify --profile-proto

  perlmogrify { --list | --list-enabled | --list-themes | --doc pattern [...] }

  perlmogrify { --help | --options | --man | --version }

DESCRIPTION

perlmogrify is a Perl5 to Perl6 code transformer. It's the executable front end to Perl::ToPerl6, which is a configurable, extensible code transfomer. Most of the code transfoermers were developed simply by taking sample Perl5 source and hand-editing it until it compiled under Perl6.

The author hopes that the resultant Perl6 code is semantically correct, but makes no guarantees. The framework is completely based on Perl::Critic and lets you use all of the extant Perl::Critic options and .perlcriticrc configurations, under the name of '.perlmogrifyrc'.

Code transformers can have options passed to them, but at the moment none of the core code transformers have options. Some basic options, such as transforming qw(a b c) into more Perl6ish <a b c> may be supported later on, but the general idea is transforming syntactically correct Perl5 code into Perl6.

This documentation only covers how to drive this command. For all other information, such as API reference and alternative interfaces, please see the documentation for Perl::ToPerl6 itself.

USAGE EXAMPLES

Before getting into all the gory details, here are some basic usage examples to help get you started.

    # Apply only core transformations
    perlmogrify YourModule.pm

    # Same as above, but read input from STDIN
    perlmogrify

    # Recursively process all Perl files beneath directory
    perlmogrify /some/directory

    # Apply slightly less severe transformations too (severity >= 4)
    perlmogrify -4 YourModule.pm

    # Same as above, but using named severity level
    perlmogrify --stern YourModule.pm

    # Apply all transformations, regardless of severity (severity >= 1)
    perlmogrify -1 YourModule.pm

    # Same as above, but using named severity level
    perlmogrify --brutal YourModule.pm

    # Apply only core transformations
    perlmogrify --theme core YourModule.pm

    # Apply additional transformations that match m/variables/xms
    perlmogrify --include variables YourModule.pm

    # Use defaults from somewhere other than ~/.perlmogrifyrc
    perlmogrify --profile project/specific/perlmogrifyrc YourModule.pm

ARGUMENTS

The arguments are paths to the files you wish to analyze. You may specify multiple files. If an argument is a directory, perlmogrify will analyze all Perl files below the directory. If no arguments are specified, then input is read from STDIN.

OPTIONS

Option names can be abbreviated to uniqueness and can be stated with single or double dashes, and option values can be separated from the option name by a space or '=' (as with Getopt::Long). Option names are also case-sensitive.

Most of these options come from the original Perl::Critic module, and are more relevant to its operation. They'll remain in the Perl::ToPerl6 source and be pressed into new duties as time allows.

The documentation still reflects their Perl::Critic usages, but again this will be rewritten as time allows.

--profile FILE or -p FILE

Directs perlmogrify to use a profile named by FILE rather than looking for the default .perlmogrifyrc file in the current directory or your home directory. See "CONFIGURATION" in Perl::ToPerl6 for more information.

--noprofile

Directs perlmogrify not to load any configuration file, thus reverting to the default configuration for all Transformers.

--severity N

Directs perlmogrify to only apply Transformers with a severity greater than N. Severity values are integers ranging from 1 (least severe) to 5 (most severe). The default is 5. For a given --profile, decreasing the --severity will usually produce more transformations. You can set the default value for this option in your .perlmogrifyrc file. You can also redefine the severity for any Transformer in your .perlmogrifyrc file. See "CONFIGURATION" for more information.

-5 | -4 | -3 | -2 | -1

These are numeric shortcuts for setting the --severity option. For example, "-4" is equivalent to "--severity 4". If multiple shortcuts are specified, then the most restrictive one wins. If an explicit --severity option is also given, then all shortcut options are silently ignored. NOTE: Be careful not to put one of the number severity shortcut options immediately after the --top flag or perlmogrify will interpret it as the number of transformations to report.

--severity NAME

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
--gentle | --stern | --harsh | --cruel | --brutal

These are named shortcuts for setting the --severity option. For example, "--cruel" is equivalent to "--severity 2". If multiple shortcuts are specified, then the most restrictive one wins. If an explicit --severity option is also given, then all shortcut options are silently ignored.

--theme RULE

Directs perlmogrify to apply only Transformers with themes that satisfy the RULE. Themes are arbitrary names for groups of related transformers. You can combine theme names with boolean operators to create an arbitrarily complex RULE. For example, the following would apply only Transformers that have a 'bugs' AND 'core' theme:

    $> perlmogrify --theme='bugs && core' MyModule.pm

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 .perlmogrifyrc file. See "TRANSFORMER THEMES" in Perl::ToPerl6 for more information about themes.

--include PATTERN

Directs perlmogrify to apply additional Transformers that match the regex /PATTERN/imx. Use this option to temporarily override your profile and/or the severity settings at the command-line. For example:

    perlmogrify --include=layout my_file.pl

This would cause perlmogrify to apply all the CodeLayout::* transformers even if they have a severity level that is less than the default level of 5, or have been disabled in your .perlmogrifyrc file. You can specify multiple --include options and you can use it in conjunction with the --exclude option. Note that --exclude takes precedence over --include when a Transformer matches both patterns. You can set the default value for this option in your .perlmogrifyrc file.

--exclude PATTERN

Directs perlmogrify to not apply any Transformer that matches the regex /PATTERN/imx. Use this option to temporarily override your profile and/or the severity settings at the command-line. For example:

    perlmogrify --exclude=strict my_file.pl

This would cause perlmogrify to not apply the RequireUseStrict and ProhibitNoStrict Policies even though they have the highest severity level. You can specify multiple --exclude options and you can use it in conjunction with the --include option. Note that --exclude takes precedence over --include when a Transformer matches both patterns. You can set the default value for this option in your .perlmogrifyrc file.

--single-policy PATTERN or -s PATTERN

Directs perlmogrify to apply just one Transformer module matching the regex /PATTERN/ixms, and exclude all other Policies. This option has precedence over the --severity, --theme, --include, --exclude, and --only options. For example:

    perlmogrify --single-policy=nowarnings my_file.pl

This would cause perlmogrify to apply just the ProhibitNoWarnings Transformer, regardless of the severity level setting. No other Transformers would be applied.

This is equivalent to what one might intend by...

    perlmogrify --exclude=. --include=nowarnings my_file.pl

... but this won't work because the --exclude option overrides the --include option.

The equivalent of this option can be accomplished by creating a custom profile containing only the desired policy and then running...

    perlmogrify --profile=customprofile --only my_file.pl
--top [ N ]

Directs perlmogrify to report only the top N Transformer transformations in each file, ranked by their severity. If N is not specified, it defaults to 20. If the --severity option (or one of the shortcuts) is not explicitly given, the --top option implies that the minimum severity level is "1" (i.e. "brutal"). Users can redefine the severity for any Transformer in their .perlmogrifyrc file. See "CONFIGURATION" for more information. You can set the default value for this option in your .perlmogrifyrc file. NOTE: Be careful not to put one of the severity shortcut options immediately after the --top flag or perlmogrify will interpret it as the number of transformations to report.

--force

Directs perlmogrify to ignore the magical "## no mogrify" annotations in the source code. See "BENDING THE RULES" for more information. You can set the default value for this option in your .perlmogrifyrc file.

--statistics

Causes several statistics about the code being scanned and the transformations found to be reported after any other output.

--statistics-only

Like the --statistics option, but suppresses normal output and only shows the statistics.

--verbose N | FORMAT

Sets the verbosity level or format for reporting transformations. If given a number (N), perlmogrify reports transformations using one of the predefined formats described below. If given a string (FORMAT), it is interpreted to be an actual format specification. If the --verbose option is not specified, it defaults to either 4 or 5, depending on whether multiple files were given as arguments to perlmogrify. You can set the default value for this option in your .perlmogrifyrc file.

    Verbosity     Format Specification
    -----------   -------------------------------------------------------
     1            "%f:%l:%c:%m\n",
     2            "%f: (%l:%c) %m\n",
     3            "%m at %f line %l\n",
     4            "%m at line %l, column %c.  %e.  (Severity: %s)\n",
     5            "%f: %m at line %l, column %c.  %e.  (Severity: %s)\n",
     6            "%m at line %l, near '%r'.  (Severity: %s)\n",
     7            "%f: %m at line %l near '%r'.  (Severity: %s)\n",
     8            "[%p] %m at line %l, column %c.  (Severity: %s)\n",
     9            "[%p] %m at line %l, near '%r'.  (Severity: %s)\n",
    10            "%m at line %l, column %c.\n  %p (Severity: %s)\n%d\n",
    11            "%m at line %l, near '%r'.\n  %p (Severity: %s)\n%d\n"

Formats are a combination of literal and escape characters similar to the way sprintf works. See String::Format for a full explanation of the formatting capabilities. Valid escape characters are:

    Escape    Meaning
    -------   ------------------------------------------------------------
    %c        Column number where the transformation occurred
    %d        Full diagnostic discussion of the transformation
    %e        Explanation of transformation
    %F        Just the name of the file where the transformation occurred.
    %f        Path to the file where the transformation occurred.
    %l        Line number where the transformation occurred
    %m        Brief description of the transformation
    %P        Full name of the Transformer module that created the transformation
    %p        Name of the Transformer without the Perl::ToPerl6::Transformer:: prefix
    %r        The string of source code that caused the transformation
    %C        The class of the PPI::Element that caused the transformation
    %s        The severity level of the transformation

The purpose of these formats is to provide some compatibility with text editors that have an interface for parsing certain kinds of input. See "EDITOR INTEGRATION" for more information about that.

--list

Displays a condensed listing of all the Perl::ToPerl6::Transformer modules that are found on this machine. This option lists all Transformers, regardless of your .perlmogrifyrc or command line options. For each Transformer, the name, default severity and default themes are shown.

--list-enabled

Displays a condensed listing of all the Perl::ToPerl6::Transformer modules that would be applied, if you were actually going to transform a file with this command. This is useful when you've constructed a complicated command or modified your .perlmogrifyrc file and you want to see exactly which Transformers are going to be enforced (or not enforced, as the case may be). For each Transformer, the name, default severity and default themes are shown.

--list-themes

Displays a list of all the themes of the Perl::ToPerl6::Transformer modules that are found on this machine.

--profile-proto

Displays an expanded listing of all the Perl::ToPerl6::Transformer modules that are found on this machine. For each Transformer, the name, default severity and default themes are shown, as well as the name of any additional parameters that the Transformer supports. The format is suitable as a prototype for your .perlmogrifyrc file.

--only

Directs perlmogrify to apply only Transformers that are explicitly mentioned in your .perlmogrifyrc file. This is useful if you want to use just a small subset of Policies without having to disable all the others. You can set the default value for this option in your .perlmogrifyrc file.

--profile-strictness {warn|fatal|quiet}

Directs perlmogrify how to treat certain recoverable problems found in a .perlmogrifyrc or file specified via the --profile option. Valid values are warn (the default), fatal, and quiet. For example, perlmogrify normally only warns about profiles referring to non-existent Transformers, but this option can make this situation fatal. You can set the default value for this option in your .perlmogrifyrc file.

--count
-C

Display only the number of transformations for each file. Use this feature to get a quick handle on where a large pile of code might need the most attention.

--color =item --colour

This option is on when outputting to a tty. When set, Severity 5 and 4 are colored red and yellow, respectively. Colorization only happens if Term::ANSIColor is installed and it only works on non-Windows environments. Negate this switch to disable color. You can set the default value for this option in your .perlmogrifyrc file.

--pager PAGER_COMMAND_STRING

If set, perlmogrify will pipe it's output to the given PAGER_COMMAND_STRING. You can set the default value for this option in your .perlmogrifyrc file.

Setting a pager turns off color by default. You will have to turn color on explicitly. If you want color, you'll probably also want to tell your pager to display raw characters. For less and more, use the -R switch.

--color-severity-highest COLOR_SPECIFICATION

Specifies the color to be used for highest severity transformations, as a Term::ANSIColor color specification. Can also be specified as --colour- severity-highest, --color-severity-5, or --colour-severity-5.

--color-severity-high COLOR_SPECIFICATION

Specifies the color to be used for high severity transformations, as a Term::ANSIColor color specification. Can also be specified as --colour- severity-high, --color-severity-4, or --colour-severity-4.

--color-severity-medium COLOR_SPECIFICATION

Specifies the color to be used for medium severity transformations, as a Term::ANSIColor color specification. Can also be specified as --colour- severity-medium, --color-severity-3, or --colour-severity-3.

--color-severity-low COLOR_SPECIFICATION

Specifies the color to be used for low severity transformations, as a Term::ANSIColor color specification. Can also be specified as --colour- severity-low, --color-severity-2, or --colour-severity-2.

--color-severity-lowest COLOR_SPECIFICATION

Specifies the color to be used for lowest severity transformations, as a Term::ANSIColor color specification. Can also be specified as --colour- severity-lowest, --color-severity-1, or --colour-severity-1.

--files-with-transformations

Display only the names of files with transformations. Use this feature with --single-policy to find files that contain transformations of a given policy. Can also be specified as --l.

--files-without-transformations

Display only the names of files without transformations. Use this feature with --single-policy to find files that do not contain transformations of a given policy. Can also be specified as --L.

--program-extensions file_name_extension

Tell perlmogrify to treat files whose names end in the given file name extension as programs, not as modules. If a leading '.' is desired it must be explicitly specified, e.g.

    --program-extensions .pl

The matching is case-sensitive, and the option may be specified as many times as desired, e.g.

    --program-extensions .pl --program-extensions .cgi

The above can also be done by quoting the file name extensions:

    --program-extensions '.pl .cgi'

Files whose name ends in '.PL' will always be considered programs.

--doc PATTERN

Displays the perldoc for all Perl::ToPerl6::Transformer modules that match m/PATTERN/ixms. Since Transformer modules tend to have rather long names, this just provides a more convenient way to say something like: "perldoc Perl::ToPerl6::Transformer::ValuesAndExpressions::RequireUpperCaseH eredocTerminator" at the command prompt.

--allow-unsafe

This option directs perlmogrify to allow the use of Policies that have been marked as "unsafe". Unsafe Policies may result in risky operations by compiling and executing the code they analyze. All the Policies that ship in the core Perl::ToPerl6 distribution are safe. However, third- party Policies, such as those in the Perl::ToPerl6::Dynamic distribution are not safe. Note that "safety" is honorary -- if a Transformer author marks a Transformer as safe, it is not a guarantee that it won't do nasty things. If you don't trust your Policies and the code you are analyzing, then do not use this switch.

--quiet

Suppress the "source OK" message when no transformations are found.

--help
-?
-H

Displays a brief summary of options and exits.

--options

Displays the descriptions of the options and exits. While this output is long, it it nowhere near the length of the output of --man.

--man

Displays the complete perlmogrify manual and exits.

--version
-V

Displays the version number of perlmogrify and exits.

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. perlmogrify 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 on the command-line, then all Transformers 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 perlmogrify itself can be set before the first named block. For example, putting any or all of these at the top of your .perlmogrifyrc file will set the default value for the corresponding command-line 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

The remainder of the configuration file is a series of blocks like this:

    [Perl::ToPerl6::Transformer::Category::TransformerName]
    severity = 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.

severity is the level of importance you wish to assign to the Transformer. All Transformer 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

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 "TRANSFORMER 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 "TRANSFORMER THEMES" for more information.

The remaining key-value pairs are configuration parameters that will be passed into the constructor of that Transformer. The constructors for most Transformer modules 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 severity 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 --severity given on the command line.

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 transformers a custom theme.  I can activate just
    # these transformers by saying "perlmogrify --theme 'larry || curly'"

    [Modules::RequireFilenameMatchesPackage]
    add_themes = larry

    [TestingAndDebugging::RequireTestLabels]
    add_themes = 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.

Note that all transformers included with the Perl::ToPerl6 distribution that have integer parameters accept underscores ("_") in their values, as with Perl numeric literals. For example,

    [ValuesAndExpressions::RequireNumberSeparators]
    min_value = 1_000

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 policy that you want, some one may have already written it. See "SEE ALSO" in Perl::ToPerl6 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 Policies. They are intended to provide an alternative mechanism for selecting your preferred set of Policies. For example, you may wish disable a certain set 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::ToPerl6 are have been divided 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               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

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 command-line option, you can create an arbitrarily complex rule that determines which Policies to apply. Precedence is the same as regular Perl code, and you can use parentheses to enforce precedence as well. Supported operators are:

    Operator    Altertative    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

For whatever reason, you may want to mark certain sections of code as "do not transform". You can do that in three basic ways - The '## no mogrify' marker tells the engine to skip transformations on the line it's on.

The '## no mogrify' comment on its own line suppresses transformation until a '## use mogrify' comment on its own line, or the end of the file, whichever comes first.

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

  for my $element (@list) {

      ## no mogrify

      $foo = "";              # Don't transform this
      $barf = bar() if $foo;  # or this
      #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 Policies, add a list of Transformer names as arguments just as you would for the "no strict" or "no warnings" pragma. For example, this would disable the Variables::FormatSigils and Variables::FormatHashKeys transformers until the end of the block or until the next "## use mogrify" annotation (whichever comes first):

    ## no mogrify (Variables::FormatSigils, Variables::FormatHashKeys);

    # Now exempt from the aforementioned transformers:
    $foo[0] = $x{foo-bar};

    $barf = bar() if $foo;

    $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 (Variables)

    # Now exempt from Variables::FormatSigils
    my $camelHumpVar = 'foo';

The argument list must be enclosed in parentheses and must contain one or more comma-separated barewords (i.e. 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 Policies like Subroutines::ProhibitExcessComplexity apply to an entire block of code. In those cases, "## no mogrify" must appear on the line where the transformations is reported. For example:

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

Some Transformers like File::Script apply to the entire document, in which case transformations are reported at line 1. But if the file requires a shebang line, it is impossible to put "## no mogrify" on the first line of the file. This is a known limitation and it will be addressed in a future release. As a workaround, you can disable the affected transformers at the command-line or in your .perlmogrifyrc file. But beware that this will affect the analysis of all files.

Use this feature wisely. "## no mogrify" 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.

EXIT STATUS

If perlmogrify has any errors itself, exits with status == 1. If there are no errors, but perlmogrify finds Transformer transformations in your source code, exits with status == 2. If there were no errors and no transformations were found, exits with status == 0.

THE Perl::ToPerl6 PHILOSOPHY

    Minimal changes for maximum effect. The transformers themselves are designed without assumptions of the order they run in, even though there's a quick-and-dirty run_before(), run_after() feature implemented so that modules can ask to be run before or after a given module or modules.

    Transformers should assume in general that they're running on Perl5 code, although you can try out the 'run_before()' feature if you want to assert that a particular transformer has been run before yours.

    The goal overall is to just help get a Perl codebase to the point where it'll compile under Perl6 with minimal changes. To that end the code is designed to make just the bare minimum of changes, and where possible use Perl5-shaped constructs, such as :P5 modifiers.

EXTENDING THE MOGRIFIER

The simplest way to go about this is find a module in the list that performs a task like what you want, copy that, and start walking its PPI tree. Each module is presumed to act on one node of the tree at a time, in other words $elem will always be a single element of the type you're modifying. This keeps code simple, and lets the main body collect statistics about what it's modifying.

For instance, when running it you'll get an *awful* lot of output about what the modules are doing, complete with line and column numbers of where the modifications are happening. This is more or less so that you can trace back to the point of origin when a module does something you don't expect.

Your module receives the original document in $doc and the element to process in $elem. If you make no modifications to the element, just return. Otherwise, calling transformation() tells the main application that your module has changed source.

Just to keep the source tree clean and reasonably Perlish, I try to create new tokens for whitespace and such where it's practical. Please also note that at some points I'm forced to violate PPI encapsulation, for instance changing brace styles or a heredoc's marker.

Something else to keep in mind as you're creating tests is that the expression you're looking for won't always begin at the start of a PPI::Statement. As a trivial example, $x++ may occur at the end of a long statement, such as 1 if $x++. So, when creating your test suites be sure that at least a few of your test cases don't begin precisely at the statement boundary.

Feel free to send me a pull request on GitHub if you've developed a module and want it integrated.

CONTACTING THE DEVELOPMENT TEAM

Currently the development team is just me, [mailto:drforr@pobox.com] or send me a pull request for the appropriate module on GitHUb. I'll keep an eye out for requests and integrate them as they come in, or within a reasonable time frame.

You can also catch me on IRC at either [irc://irc.perl.org/#perl] or [irc://irc.freenode.net/#perl], and follow me on Twitter at [https://twitter.com/drforr]

BUGS

Feel free to submit bugs via either RT or GitHub. GitHub and personal email gets checked more frequently, or just bounce me a note on IRC if I happen to be active.

CREDITS

Jeffrey Thalhammer - For creating the framework I'm shamelessly ripping off, so I don't have to create an entire plugin architecture.

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

Damian Conway - For writing Perl Best Practices, finally :)

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.

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 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 <drforr@pobox.com>. 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.