Yet another way to declare CPAN dependencies
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Module::CPANfile - Parse cpanfile


use Module::CPANfile;

my $file = Module::CPANfile->load("cpanfile");
my $prereqs = $file->prereqs; # CPAN::Meta::Prereqs object

my @features = $file->features; # CPAN::Meta::Feature objects
my $merged_prereqs = $file->prereqs_with(@identifiers); # CPAN::Meta::Prereqs



Module::CPANfile is a tool to handle cpanfile format to load application specific dependencies, not just for CPAN distributions.


  • load

      $file = Module::CPANfile->load;
      $file = Module::CPANfile->load('cpanfile');

    Load and parse a cpanfile. By default it tries to load cpanfile in the current directory, unless you pass the path to its argument.

  • from_prereqs

      $file = Module::CPANfile->from_prereqs({
        runtime => { requires => { DBI => '1.000' } },

    Creates a new Module::CPANfile object from prereqs hash you can get via CPAN::Meta's prereqs, or CPAN::Meta::Prereqs' as_string_hash.

      # read MYMETA, then feed the prereqs to create Module::CPANfile
      my $meta = CPAN::Meta->load_file('MYMETA.json');
      my $file = Module::CPANfile->from_prereqs($meta->prereqs);
      # load cpanfile, then recreate it with round-trip
      my $file = Module::CPANfile->load('cpanfile');
      $file = Module::CPANfile->from_prereqs($file->prereq_specs);
                                        # or $file->prereqs->as_string_hash
  • prereqs

    Returns CPAN::Meta::Prereqs object out of the parsed cpanfile.

  • prereq_specs

    Returns a hash reference that should be passed to CPAN::Meta::Prereqs->new.

  • features

    Returns a list of features available in the cpanfile as CPAN::Meta::Feature.

  • prereqs_with(@identifiers), effective_prereqs(\@identifiers)

    Returns CPAN::Meta::Prereqs object, with merged prereqs for features identified with the @identifiers.

  • to_string($include_empty)


    Returns a canonical string (code) representation for cpanfile. Useful if you want to convert CPAN::Meta::Prereqs to a new cpanfile.

      # read MYMETA's prereqs and print cpanfile representation of it
      my $meta = CPAN::Meta->load_file('MYMETA.json');
      my $file = Module::CPANfile->from_prereqs($meta->prereqs);
      print $file->to_string;

    By default, it omits the phase where there're no modules registered. If you pass the argument of a true value, it will print them as well.

  • save


    Saves the currently loaded prereqs as a new cpanfile by calling to_string. Beware this method will overwrite the existing cpanfile without any warning or backup. Taking a backup or giving warnings to users is a caller's responsibility.

      # Read MYMETA.json and creates a new cpanfile
      my $meta = CPAN::Meta->load_file('MYMETA.json');
      my $file = Module::CPANfile->from_prereqs($meta->prereqs);
  • merge_meta

      $file->merge_meta('MYMETA.json', '2.0');

    Merge the effective prereqs with Meta specification loaded from the given META file, using CPAN::Meta. You can specify the META spec version in the second argument, which defaults to 1.4 in case the given file is YAML, and 2 if it is JSON.


Tatsuhiko Miyagawa


cpanfile, CPAN::Meta, CPAN::Meta::Spec