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.\" ========================================================================
.\"
.IX Title "CPAN::Meta 3perl"
.TH CPAN::Meta 3perl "2021-09-24" "perl v5.32.1" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
CPAN::Meta \- the distribution metadata for a CPAN dist
.SH "VERSION"
.IX Header "VERSION"
version 2.150010
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 5
\&    use v5.10;
\&    use strict;
\&    use warnings;
\&    use CPAN::Meta;
\&    use Module::Load;
\&
\&    my $meta = CPAN::Meta\->load_file(\*(AqMETA.json\*(Aq);
\&
\&    printf "testing requirements for %s version %s\en",
\&    $meta\->name,
\&    $meta\->version;
\&
\&    my $prereqs = $meta\->effective_prereqs;
\&
\&    for my $phase ( qw/configure runtime build test/ ) {
\&        say "Requirements for $phase:";
\&        my $reqs = $prereqs\->requirements_for($phase, "requires");
\&        for my $module ( sort $reqs\->required_modules ) {
\&            my $status;
\&            if ( eval { load $module unless $module eq \*(Aqperl\*(Aq; 1 } ) {
\&                my $version = $module eq \*(Aqperl\*(Aq ? $] : $module\->VERSION;
\&                $status = $reqs\->accepts_module($module, $version)
\&                        ? "$version ok" : "$version not ok";
\&            } else {
\&                $status = "missing"
\&            };
\&            say "  $module ($status)";
\&        }
\&    }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Software distributions released to the \s-1CPAN\s0 include a \fI\s-1META\s0.json\fR or, for
older distributions, \fI\s-1META\s0.yml\fR, which describes the distribution, its
contents, and the requirements for building and installing the distribution.
The data structure stored in the \fI\s-1META\s0.json\fR file is described in
CPAN::Meta::Spec.
.PP
CPAN::Meta provides a simple class to represent this distribution metadata (or
\&\fIdistmeta\fR), along with some helpful methods for interrogating that data.
.PP
The documentation below is only for the methods of the CPAN::Meta object.  For
information on the meaning of individual fields, consult the spec.
.SH "METHODS"
.IX Header "METHODS"
.SS "new"
.IX Subsection "new"
.Vb 1
\&  my $meta = CPAN::Meta\->new($distmeta_struct, \e%options);
.Ve
.PP
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.
.PP
It takes an optional hashref of options. Valid options include:
.IP "\(bu" 4
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.
.SS "create"
.IX Subsection "create"
.Vb 1
\&  my $meta = CPAN::Meta\->create($distmeta_struct, \e%options);
.Ve
.PP
This is same as \f(CW\*(C`new()\*(C'\fR, except that \f(CW\*(C`generated_by\*(C'\fR and \f(CW\*(C`meta\-spec\*(C'\fR fields
will be generated if not provided.  This means the metadata structure is
assumed to otherwise follow the latest CPAN::Meta::Spec.
.SS "load_file"
.IX Subsection "load_file"
.Vb 1
\&  my $meta = CPAN::Meta\->load_file($distmeta_file, \e%options);
.Ve
.PP
Given a pathname to a file containing metadata, this deserializes the file
according to its file suffix and constructs a new \f(CW\*(C`CPAN::Meta\*(C'\fR object, just
like \f(CW\*(C`new()\*(C'\fR.  It will die if the deserialized version fails to validate
against its stated specification version.
.PP
It takes the same options as \f(CW\*(C`new()\*(C'\fR but \f(CW\*(C`lazy_validation\*(C'\fR defaults to
true.
.SS "load_yaml_string"
.IX Subsection "load_yaml_string"
.Vb 1
\&  my $meta = CPAN::Meta\->load_yaml_string($yaml, \e%options);
.Ve
.PP
This method returns a new CPAN::Meta object using the first document in the
given \s-1YAML\s0 string.  In other respects it is identical to \f(CW\*(C`load_file()\*(C'\fR.
.SS "load_json_string"
.IX Subsection "load_json_string"
.Vb 1
\&  my $meta = CPAN::Meta\->load_json_string($json, \e%options);
.Ve
.PP
This method returns a new CPAN::Meta object using the structure represented by
the given \s-1JSON\s0 string.  In other respects it is identical to \f(CW\*(C`load_file()\*(C'\fR.
.SS "load_string"
.IX Subsection "load_string"
.Vb 1
\&  my $meta = CPAN::Meta\->load_string($string, \e%options);
.Ve
.PP
If you don't know if a string contains \s-1YAML\s0 or \s-1JSON,\s0 this method will use
Parse::CPAN::Meta to guess.  In other respects it is identical to
\&\f(CW\*(C`load_file()\*(C'\fR.
.SS "save"
.IX Subsection "save"
.Vb 1
\&  $meta\->save($distmeta_file, \e%options);
.Ve
.PP
Serializes the object as \s-1JSON\s0 and writes it to the given file.  The only valid
option is \f(CW\*(C`version\*(C'\fR, which defaults to '2'. On Perl 5.8.1 or later, the file
is saved with \s-1UTF\-8\s0 encoding.
.PP
For \f(CW\*(C`version\*(C'\fR 2 (or higher), the filename should end in '.json'.  \s-1JSON::PP\s0
is the default \s-1JSON\s0 backend. Using another \s-1JSON\s0 backend requires \s-1JSON\s0 2.5 or
later and you must set the \f(CW$ENV{PERL_JSON_BACKEND}\fR to a supported alternate
backend like \s-1JSON::XS\s0.
.PP
For \f(CW\*(C`version\*(C'\fR less than 2, the filename should end in '.yml'.
CPAN::Meta::Converter is used to generate an older metadata structure, which
is serialized to \s-1YAML.\s0  CPAN::Meta::YAML is the default \s-1YAML\s0 backend.  You may
set the \f(CW$ENV{PERL_YAML_BACKEND}\fR to a supported alternative backend, though
this is not recommended due to subtle incompatibilities between \s-1YAML\s0 parsers on
\&\s-1CPAN.\s0
.SS "meta_spec_version"
.IX Subsection "meta_spec_version"
This method returns the version part of the \f(CW\*(C`meta_spec\*(C'\fR entry in the distmeta
structure.  It is equivalent to:
.PP
.Vb 1
\&  $meta\->meta_spec\->{version};
.Ve
.SS "effective_prereqs"
.IX Subsection "effective_prereqs"
.Vb 1
\&  my $prereqs = $meta\->effective_prereqs;
\&
\&  my $prereqs = $meta\->effective_prereqs( \e@feature_identifiers );
.Ve
.PP
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.
.SS "should_index_file"
.IX Subsection "should_index_file"
.Vb 1
\&  ... if $meta\->should_index_file( $filename );
.Ve
.PP
This method returns true if the given file should be indexed.  It decides this
by checking the \f(CW\*(C`file\*(C'\fR and \f(CW\*(C`directory\*(C'\fR keys in the \f(CW\*(C`no_index\*(C'\fR property of
the distmeta structure. Note that neither the version format nor
\&\f(CW\*(C`release_status\*(C'\fR are considered.
.PP
\&\f(CW$filename\fR should be given in unix format.
.SS "should_index_package"
.IX Subsection "should_index_package"
.Vb 1
\&  ... if $meta\->should_index_package( $package );
.Ve
.PP
This method returns true if the given package should be indexed.  It decides
this by checking the \f(CW\*(C`package\*(C'\fR and \f(CW\*(C`namespace\*(C'\fR keys in the \f(CW\*(C`no_index\*(C'\fR
property of the distmeta structure. Note that neither the version format nor
\&\f(CW\*(C`release_status\*(C'\fR are considered.
.SS "features"
.IX Subsection "features"
.Vb 1
\&  my @feature_objects = $meta\->features;
.Ve
.PP
This method returns a list of CPAN::Meta::Feature objects, one for each
optional feature described by the distribution's metadata.
.SS "feature"
.IX Subsection "feature"
.Vb 1
\&  my $feature_object = $meta\->feature( $identifier );
.Ve
.PP
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.
.SS "as_struct"
.IX Subsection "as_struct"
.Vb 1
\&  my $copy = $meta\->as_struct( \e%options );
.Ve
.PP
This method returns a deep copy of the object's metadata as an unblessed hash
reference.  It takes an optional hashref of options.  If the hashref contains
a \f(CW\*(C`version\*(C'\fR argument, the copied metadata will be converted to the version
of the specification and returned.  For example:
.PP
.Vb 1
\&  my $old_spec = $meta\->as_struct( {version => "1.4"} );
.Ve
.SS "as_string"
.IX Subsection "as_string"
.Vb 1
\&  my $string = $meta\->as_string( \e%options );
.Ve
.PP
This method returns a serialized copy of the object's metadata as a character
string.  (The strings are \fBnot\fR \s-1UTF\-8\s0 encoded.)  It takes an optional hashref
of options.  If the hashref contains a \f(CW\*(C`version\*(C'\fR argument, the copied metadata
will be converted to the version of the specification and returned.  For
example:
.PP
.Vb 1
\&  my $string = $meta\->as_string( {version => "1.4"} );
.Ve
.PP
For \f(CW\*(C`version\*(C'\fR greater than or equal to 2, the string will be serialized as
\&\s-1JSON.\s0  For \f(CW\*(C`version\*(C'\fR less than 2, the string will be serialized as \s-1YAML.\s0  In
both cases, the same rules are followed as in the \f(CW\*(C`save()\*(C'\fR method for choosing
a serialization backend.
.PP
The serialized structure will include a \f(CW\*(C`x_serialization_backend\*(C'\fR entry giving
the package and version used to serialize.  Any existing key in the given
\&\f(CW$meta\fR object will be clobbered.
.SH "STRING DATA"
.IX Header "STRING DATA"
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.
.IP "\(bu" 4
abstract
.IP "\(bu" 4
description
.IP "\(bu" 4
dynamic_config
.IP "\(bu" 4
generated_by
.IP "\(bu" 4
name
.IP "\(bu" 4
release_status
.IP "\(bu" 4
version
.SH "LIST DATA"
.IX Header "LIST DATA"
These methods return lists of string values, which might be represented in the
distmeta structure as arrayrefs or scalars:
.IP "\(bu" 4
authors
.IP "\(bu" 4
keywords
.IP "\(bu" 4
licenses
.PP
The \f(CW\*(C`authors\*(C'\fR and \f(CW\*(C`licenses\*(C'\fR methods may also be called as \f(CW\*(C`author\*(C'\fR and
\&\f(CW\*(C`license\*(C'\fR, respectively, to match the field name in the distmeta structure.
.SH "MAP DATA"
.IX Header "MAP DATA"
These readers return hashrefs of arbitrary unblessed data structures, each
described more fully in the specification:
.IP "\(bu" 4
meta_spec
.IP "\(bu" 4
resources
.IP "\(bu" 4
provides
.IP "\(bu" 4
no_index
.IP "\(bu" 4
prereqs
.IP "\(bu" 4
optional_features
.SH "CUSTOM DATA"
.IX Header "CUSTOM DATA"
A list of custom keys are available from the \f(CW\*(C`custom_keys\*(C'\fR method and
particular keys may be retrieved with the \f(CW\*(C`custom\*(C'\fR method.
.PP
.Vb 1
\&  say $meta\->custom($_) for $meta\->custom_keys;
.Ve
.PP
If a custom key refers to a data structure, a deep clone is returned.
.SH "BUGS"
.IX Header "BUGS"
Please report any bugs or feature using the \s-1CPAN\s0 Request Tracker.
Bugs can be submitted through the web interface at
<http://rt.cpan.org/Dist/Display.html?Queue=CPAN\-Meta>
.PP
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.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
.IP "\(bu" 4
CPAN::Meta::Converter
.IP "\(bu" 4
CPAN::Meta::Validator
.SH "SUPPORT"
.IX Header "SUPPORT"
.SS "Bugs / Feature Requests"
.IX Subsection "Bugs / Feature Requests"
Please report any bugs or feature requests through the issue tracker
at <https://github.com/Perl\-Toolchain\-Gang/CPAN\-Meta/issues>.
You will be notified automatically of any progress on your issue.
.SS "Source Code"
.IX Subsection "Source Code"
This is open source software.  The code repository is available for
public review and contribution under the terms of the license.
.PP
<https://github.com/Perl\-Toolchain\-Gang/CPAN\-Meta>
.PP
.Vb 1
\&  git clone https://github.com/Perl\-Toolchain\-Gang/CPAN\-Meta.git
.Ve
.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 "CONTRIBUTORS"
.IX Header "CONTRIBUTORS"
.IP "\(bu" 4
Ansgar Burchardt <ansgar@cpan.org>
.IP "\(bu" 4
Avar Arnfjord Bjarmason <avar@cpan.org>
.IP "\(bu" 4
Benjamin Noggle <agwind@users.noreply.github.com>
.IP "\(bu" 4
Christopher J. Madsen <cjm@cpan.org>
.IP "\(bu" 4
Chuck Adams <cja987@gmail.com>
.IP "\(bu" 4
Cory G Watson <gphat@cpan.org>
.IP "\(bu" 4
Damyan Ivanov <dam@cpan.org>
.IP "\(bu" 4
David Golden <xdg@xdg.me>
.IP "\(bu" 4
Eric Wilhelm <ewilhelm@cpan.org>
.IP "\(bu" 4
Graham Knop <haarg@haarg.org>
.IP "\(bu" 4
Gregor Hermann <gregoa@debian.org>
.IP "\(bu" 4
Karen Etheridge <ether@cpan.org>
.IP "\(bu" 4
Kenichi Ishigaki <ishigaki@cpan.org>
.IP "\(bu" 4
Kent Fredric <kentfredric@gmail.com>
.IP "\(bu" 4
Ken Williams <kwilliams@cpan.org>
.IP "\(bu" 4
Lars Dieckow <daxim@cpan.org>
.IP "\(bu" 4
Leon Timmermans <leont@cpan.org>
.IP "\(bu" 4
majensen <maj@fortinbras.us>
.IP "\(bu" 4
Mark Fowler <markf@cpan.org>
.IP "\(bu" 4
Matt S Trout <mst@shadowcat.co.uk>
.IP "\(bu" 4
Michael G. Schwern <mschwern@cpan.org>
.IP "\(bu" 4
Mohammad S Anwar <mohammad.anwar@yahoo.com>
.IP "\(bu" 4
mohawk2 <mohawk2@users.noreply.github.com>
.IP "\(bu" 4
moznion <moznion@gmail.com>
.IP "\(bu" 4
Niko Tyni <ntyni@debian.org>
.IP "\(bu" 4
Olaf Alders <olaf@wundersolutions.com>
.IP "\(bu" 4
Olivier Mengué <dolmen@cpan.org>
.IP "\(bu" 4
Randy Sims <randys@thepierianspring.org>
.IP "\(bu" 4
Tomohiro Hosaka <bokutin@bokut.in>
.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.