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CPAN::Meta::Prereqs - a set of distribution prerequisites by phase and type


version 2.150005


A CPAN::Meta::Prereqs object represents the prerequisites for a CPAN distribution or one of its optional features. Each set of prereqs is organized by phase and type, as described in CPAN::Meta::Prereqs.



my $prereq = CPAN::Meta::Prereqs->new( \%prereq_spec );

This method returns a new set of Prereqs. The input should look like the contents of the prereqs field described in CPAN::Meta::Spec, meaning something more or less like this:

my $prereq = CPAN::Meta::Prereqs->new({
  runtime => {
    requires => {
      'Some::Module' => '1.234',

You can also construct an empty set of prereqs with:

my $prereqs = CPAN::Meta::Prereqs->new;

This empty set of prereqs is useful for accumulating new prereqs before finally dumping the whole set into a structure or string.


my $requirements = $prereqs->requirements_for( $phase, $type );

This method returns a CPAN::Meta::Requirements object for the given phase/type combination. If no prerequisites are registered for that combination, a new CPAN::Meta::Requirements object will be returned, and it may be added to as needed.

If $phase or $type are undefined or otherwise invalid, an exception will be raised.


my $new_prereqs = $prereqs->with_merged_prereqs( $other_prereqs );

my $new_prereqs = $prereqs->with_merged_prereqs( \@other_prereqs );

This method returns a new CPAN::Meta::Prereqs objects in which all the other prerequisites given are merged into the current set. This is primarily provided for combining a distribution's core prereqs with the prereqs of one of its optional features.

The new prereqs object has no ties to the originals, and altering it further will not alter them.


my $new_reqs = $prereqs->merged_requirements( \@phases, \@types );
my $new_reqs = $prereqs->merged_requirements( \@phases );
my $new_reqs = $prereqs->merged_requirements();

This method joins together all requirements across a number of phases and types into a new CPAN::Meta::Requirements object. If arguments are omitted, it defaults to "runtime", "build" and "test" for phases and "requires" and "recommends" for types.


This method returns a hashref containing structures suitable for dumping into a distmeta data structure. It is made up of hashes and strings, only; there will be no Prereqs, CPAN::Meta::Requirements, or version objects inside it.


This method returns true if the set of prereqs has been marked "finalized," and cannot be altered.


Calling finalize on a Prereqs object will close it for further modification. Attempting to make any changes that would actually alter the prereqs will result in an exception being thrown.


my $cloned_prereqs = $prereqs->clone;

This method returns a Prereqs object that is identical to the original object, but can be altered without affecting the original object. Finalization does not survive cloning, meaning that you may clone a finalized set of prereqs and then modify the clone.


Please report any bugs or feature using the CPAN Request Tracker. Bugs can be submitted through the web interface at

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.



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.