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.\" ========================================================================
.\"
.IX Title "CPAN::Meta::Merge 3"
.TH CPAN::Meta::Merge 3 "2016-08-18" "perl v5.16.3" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
CPAN::Meta::Merge \- Merging CPAN Meta fragments
.SH "VERSION"
.IX Header "VERSION"
version 2.150010
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& my $merger = CPAN::Meta::Merge\->new(default_version => "2");
\& my $meta = $merger\->merge($base, @additional);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
.SH "METHODS"
.IX Header "METHODS"
.SS "new"
.IX Subsection "new"
This creates a CPAN::Meta::Merge object. It takes one mandatory named
argument, \f(CW\*(C`version\*(C'\fR, declaring the version of the meta-spec that must be
used for the merge. It can optionally take an \f(CW\*(C`extra_mappings\*(C'\fR argument
that allows one to add additional merging functions for specific elements.
.PP
The \f(CW\*(C`extra_mappings\*(C'\fR 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.
.PP
.Vb 11
\&  my $merger = CPAN::Meta::Merge\->new(
\&      default_version => \*(Aq2\*(Aq,
\&      extra_mappings => {
\&          \*(Aqoptional_features\*(Aq => \e&custom_merge_function,
\&          \*(Aqx_custom\*(Aq => \*(Aqset_addition\*(Aq,
\&          \*(Aqx_meta_meta\*(Aq => {
\&              name => \*(Aqidentical\*(Aq,
\&              tags => \*(Aqset_addition\*(Aq,
\&          }
\&      }
\&  );
.Ve
.SS "merge(@fragments)"
.IX Subsection "merge(@fragments)"
Merge all \f(CW@fragments\fR together. It will accept both CPAN::Meta objects and
(possibly incomplete) hashrefs of metadata.
.SH "MERGE STRATEGIES"
.IX Header "MERGE STRATEGIES"
\&\f(CW\*(C`merge\*(C'\fR uses various strategies to combine different elements of the CPAN::Meta objects.  The following strategies can be used with the extra_mappings argument of \f(CW\*(C`new\*(C'\fR:
.IP "identical" 4
.IX Item "identical"
The elements must be identical
.IP "set_addition" 4
.IX Item "set_addition"
The union of two array refs
.Sp
.Vb 1
\&  [ a, b ] U [ a, c]  = [ a, b, c ]
.Ve
.IP "uniq_map" 4
.IX Item "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.
.IP "improvise" 4
.IX Item "improvise"
This merge strategy will try to pick the appropriate predefined strategy
based on what element type.  Array refs will try to use the
\&\f(CW\*(C`set_addition\*(C'\fR strategy,  Hash refs will try to use the \f(CW\*(C`uniq_map\*(C'\fR
strategy, and everything else will try the \f(CW\*(C`identical\*(C'\fR strategy.
.SH "AUTHORS"
.IX Header "AUTHORS"
.IP "\(bu" 4
David Golden <dagolden@cpan.org>
.IP "\(bu" 4
Ricardo Signes <rjbs@cpan.org>
.IP "\(bu" 4
Adam Kennedy <adamk@cpan.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2010 by David Golden, Ricardo Signes, Adam Kennedy and Contributors.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.