The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.


MooseX::Getopt - A Moose role for processing command line options


  ## In your class
  package My::App;
  use Moose;

  with 'MooseX::Getopt';

  has 'out' => (is => 'rw', isa => 'Str', required => 1);
  has 'in'  => (is => 'rw', isa => 'Str', required => 1);

  # ... rest of the class here

  ## in your script

  use My::App;

  my $app = My::App->new_with_options();
  # ... rest of the script here

  ## on the command line
  % perl -in file.input -out file.dump


This is a role which provides an alternate constructor for creating objects using parameters passed in from the command line.

This module attempts to DWIM as much as possible with the command line params by introspecting your class's attributes. It will use the name of your attribute as the command line option, and if there is a type constraint defined, it will configure Getopt::Long to handle the option accordingly.

You can use the trait MooseX::Getopt::Meta::Attribute::Trait or the attribute metaclass MooseX::Getopt::Meta::Attribute to get non-default commandline option names and aliases.

You can use the trait MooseX::Getopt::Meta::Attribute::Trait::NoGetopt or the attribute metaclass MooseX::Getopt::Meta::Attribute::NoGetopt to have MooseX::Getopt ignore your attribute in the commandline options.

By default, attributes which start with an underscore are not given commandline argument support, unless the attribute's metaclass is set to MooseX::Getopt::Meta::Attribute. If you don't want you accessors to have the leading underscore in thier name, you can do this:

  # for read/write attributes
  has '_foo' => (accessor => 'foo', ...);

  # or for read-only attributes
  has '_bar' => (reader => 'bar', ...);

This will mean that Getopt will not handle a --foo param, but your code can still call the foo method.

If your class also uses a configfile-loading role based on MooseX::ConfigFromFile, such as MooseX::SimpleConfig, MooseX::Getopt's new_with_options will load the configfile specified by the --configfile option (or the default you've given for the configfile attribute) for you.

Options specified in multiple places follow the following precendence order: commandline overrides configfile, which overrides explicit new_with_options parameters.

Supported Type Constraints


A Bool type constraint is set up as a boolean option with Getopt::Long. So that this attribute description:

  has 'verbose' => (is => 'rw', isa => 'Bool');

would translate into verbose! as a Getopt::Long option descriptor, which would enable the following command line options:

  % --verbose
  % --noverbose
Int, Float, Str

These type constraints are set up as properly typed options with Getopt::Long, using the =i, =f and =s modifiers as appropriate.


An ArrayRef type constraint is set up as a multiple value option in Getopt::Long. So that this attribute description:

  has 'include' => (
      is      => 'rw',
      isa     => 'ArrayRef',
      default => sub { [] }

would translate into includes=s@ as a Getopt::Long option descriptor, which would enable the following command line options:

  % --include /usr/lib --include /usr/local/lib

A HashRef type constraint is set up as a hash value option in Getopt::Long. So that this attribute description:

  has 'define' => (
      is      => 'rw',
      isa     => 'HashRef',
      default => sub { {} }

would translate into define=s% as a Getopt::Long option descriptor, which would enable the following command line options:

  % --define os=linux --define vendor=debian

Custom Type Constraints

It is possible to create custom type constraint to option spec mappings if you need them. The process is fairly simple (but a little verbose maybe). First you create a custom subtype, like so:

  subtype 'ArrayOfInts'
      => as 'ArrayRef'
      => where { scalar (grep { looks_like_number($_) } @$_)  };

Then you register the mapping, like so:

      'ArrayOfInts' => '=i@'

Now any attribute declarations using this type constraint will get the custom option spec. So that, this:

  has 'nums' => (
      is      => 'ro',
      isa     => 'ArrayOfInts',
      default => sub { [0] }

Will translate to the following on the command line:

  % --nums 5 --nums 88 --nums 199

This example is fairly trivial, but more complex validations are easily possible with a little creativity. The trick is balancing the type constraint validations with the Getopt::Long validations.

Better examples are certainly welcome :)

Inferred Type Constraints

If you define a custom subtype which is a subtype of one of the standard "Supported Type Constraints" above, and do not explicitly provide custom support as in "Custom Type Constraints" above, MooseX::Getopt will treat it like the parent type for Getopt purposes.

For example, if you had the same custom ArrayOfInts subtype from the examples above, but did not add a new custom option type for it to the OptionTypeMap, it would be treated just like a normal ArrayRef type for Getopt purposes (that is, =s@).


new_with_options (%params)

This method will take a set of default %params and then collect params from the command line (possibly overriding those in %params) and then return a newly constructed object.

If "GetOptions" in Getopt::Long fails (due to invalid arguments), new_with_options will throw an exception.

If you have Getopt::Long::Descriptive a the usage param is also passed to new.


This accessor contains a reference to a copy of the @ARGV array as it originally existed at the time of new_with_options.


This accessor contains an arrayref of leftover @ARGV elements that Getopt::Long did not parse. Note that the real @ARGV is left un-mangled.


This returns the role meta object.


All complex software has bugs lurking in it, and this module is no exception. If you find a bug please either email me, or add the bug to cpan-RT.


Stevan Little <>

Brandon L. Black, <>

Yuval Kogman, <>


Ryan D Johnson, <>


Copyright 2007-2008 by Infinity Interactive, Inc.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.