++ed by:

15 PAUSE users
7 non-PAUSE users.

David Golden
and 1 contributors


CPAN::Meta - the distribution metadata for a CPAN dist


version 2.101610


  my $meta = CPAN::Meta->load_file('META.json');

  printf "testing requirements for %s version %s\n",

  my $prereqs = $meta->requirements_for('configure');

  for my $module ($prereqs->required_modules) {
    my $version = get_local_version($module);

    die "missing required module $module" unless defined $version;
    die "version for $module not in range"
      unless $prereqs->accepts_module($module, $version);


Software distributions released to the CPAN include a META.json or, for older distributions, META.yml, which describes the distribution, its contents, and the requirements for building and installing the distribution. The data structure stored in the META.json file is described in CPAN::Meta::Spec.

CPAN::Meta provides a simple class to represent this distribution metadata (or distmeta), along with some helpful methods for interrogating that data.

The documentation below is only for the methods of the CPAN::Meta object. For information on the meaning of individual fields, consult the spec.



  my $meta = CPAN::Meta->new($distmeta_struct, \%options);

Returns a valid CPAN::Meta object or dies if the supplied metadata hash reference fails to validate. Older-format metadata will be up-converted to version 2 if they validate against the original stated specification.

Valid options include:

  • lazy_validation -- if true, new will attempt to convert the given metadata to version 2 before attempting to validate it. This means than any fixable errors will be handled by CPAN::Meta::Converter before validation. (Note that this might result in invalid optional data being silently dropped.) The default is false.


  my $meta = CPAN::Meta->create($distmeta_struct);

This is same as new(), except that generated_by and meta-spec fields will be generated if not provided. This means the metadata structure is assumed to otherwise follow the latest CPAN::Meta::Spec.


  my $meta = CPAN::Meta->load_file($distmeta_file, \%options);

Given a pathname to a file containing metadata, this deserializes the file according to its file suffix and constructs a new CPAN::Meta object, just like new(). It will die if the deserialized version fails to validate against its stated specification version.

It takes the same options as new() but lazy_validation defaults to true.


  my $meta = CPAN::Meta->load_yaml_string($yaml, \%options);

This method returns a new CPAN::Meta object using the first document in the given YAML string. In other respects it is identical to load_file().


  my $meta = CPAN::Meta->load_json_string($json, \%options);

This method returns a new CPAN::Meta object using the structure represented by the given JSON string. In other respects it is identical to load_file().



Serializes the object as JSON and writes it to the given file. The filename should end in '.json'.


This method returns the version part of the meta_spec entry in the distmeta structure. It is equivalent to:



  my $prereqs = $meta->effective_prereqs;

  my $prereqs = $meta->effective_prereqs( \@feature_identifiers );

This method returns a CPAN::Meta::Prereqs object describing all the prereqs for the distribution. If an arrayref of feature identifiers is given, the prereqs for the identified features are merged together with the distribution's core prereqs before the CPAN::Meta::Prereqs object is returned.


  ... if $meta->should_index_file( $filename );

This method returns true if the given file should be indexed. It decides this by checking the file and directory keys in the no_index property of the distmeta structure.

$filename should be given in unix format.


  ... if $meta->should_index_package( $package );

This method returns true if the given package should be indexed. It decides this by checking the package and namespace keys in the no_index property of the distmeta structure.


  my @feature_objects = $meta->features;

This method returns a list of CPAN::Meta::Feature objects, one for each optional feature described by the distribution's metadata.


  my $feature_object = $meta->feature( $identifier );

This method returns a CPAN::Meta::Feature object for the optional feature with the given identifier. If no feature with that identifier exists, an exception will be raised.


  my $copy = $meta->as_struct;

This method returns a deep copy of the object's metadata as an unblessed has reference. This is useful for raw analysis or for passing to a converter object. For example:

  my $cmc = CPAN::Meta::Converter->new( $meta->as_struct );
  my $meta_1_4 = $cmc->convert( version => "1.4" );


The following methods return a single value, which is the value for the corresponding entry in the distmeta structure. Values should be either undef or strings.

  • abstract

  • description

  • dynamic_config

  • generated_by

  • name

  • release_status

  • version


These methods return lists of string values, which might be represented in the distmeta structure as arrayrefs or scalars:

  • authors

  • keywords

  • licenses

The authors and licenses methods may also be called as author and license, respectively, to match the field name in the distmeta structure.


These readers return hashrefs of arbitrary unblessed data structures, each described more fully in the specification:

  • meta_spec

  • resources

  • provides

  • no_index

  • prereqs

  • optional_features


A list of custom keys are available from the custom_keys method and particular keys may be retrieved with the custom method.

  say $meta->custom($_) for $meta->custom_keys;

If a custom key refers to a data structure, a deep clone is returned.


Please report any bugs or feature using the CPAN Request Tracker. Bugs can be submitted through the web interface at http://rt.cpan.org/Dist/Display.html?Queue=CPAN-Meta

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.



  David Golden <dagolden@cpan.org>
  Ricardo Signes <rjbs@cpan.org>


This software is copyright (c) 2010 by David Golden and Ricardo Signes.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.