Perl 5 version 32.0 documentation



CPAN::Meta::Merge - Merging CPAN Meta fragments


version 2.150010


  1. my $merger = CPAN::Meta::Merge->new(default_version => "2");
  2. my $meta = $merger->merge($base, @additional);




This creates a CPAN::Meta::Merge object. It takes one mandatory named argument, version , declaring the version of the meta-spec that must be used for the merge. It can optionally take an extra_mappings argument that allows one to add additional merging functions for specific elements.

The extra_mappings arguments takes a hash ref with the same type of structure as described in CPAN::Meta::Spec, except with its values as one of the defined merge strategies or a code ref to a merging function.

  1. my $merger = CPAN::Meta::Merge->new(
  2. default_version => '2',
  3. extra_mappings => {
  4. 'optional_features' => \&custom_merge_function,
  5. 'x_custom' => 'set_addition',
  6. 'x_meta_meta' => {
  7. name => 'identical',
  8. tags => 'set_addition',
  9. }
  10. }
  11. );


Merge all @fragments together. It will accept both CPAN::Meta objects and (possibly incomplete) hashrefs of metadata.


merge uses various strategies to combine different elements of the CPAN::Meta objects. The following strategies can be used with the extra_mappings argument of new :

  • identical

    The elements must be identical

  • set_addition

    The union of two array refs

    1. [ a, b ] U [ a, c] = [ a, b, c ]
  • uniq_map

    Key value pairs from the right hash are merged to the left hash. Key collisions are only allowed if their values are the same. This merge function will recurse into nested hash refs following the same merge rules.

  • improvise

    This merge strategy will try to pick the appropriate predefined strategy based on what element type. Array refs will try to use the set_addition strategy, Hash refs will try to use the uniq_map strategy, and everything else will try the identical strategy.


  • David Golden <>

  • Ricardo Signes <>

  • Adam Kennedy <>


This software is copyright (c) 2010 by David Golden, Ricardo Signes, Adam Kennedy and Contributors.

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