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NAME
CPAN::Meta::History::Meta_1_1 - Version 1.1 metadata specification for META.yml
PREFACE
This is a historical copy of the version 1.1 specification for META.yml files, copyright by Ken Williams.
Modifications from the original:
• Conversion from the original HTML to POD format
• Include list of valid licenses from Module::Build 0.18 rather than linking to the module.
DESCRIPTION
This document describes version 1.1 of the META.yml specification.
The META.yml file describes important properties of contributed Perl distributions such as the ones found
on CPAN <http://www.cpan.org>. It is typically created by tools like Module::Build and
ExtUtils::MakeMaker.
The fields in the META.yml file are meant to be helpful to people maintaining module collections (like
CPAN), for people writing installation tools (like CPAN or CPANPLUS), or just people who want to know
some stuff about a distribution before downloading it and starting to install it.
Format
META.yml files are written in the YAML <http://www.yaml.org/> format. The reasons we chose YAML instead
of, say, XML or Data::Dumper are discussed in this thread
<http://archive.develooper.com/makemaker@perl.org/msg00405.html> on the MakeMaker mailing list.
The first line of a META.yml file should be a valid YAML document header
<http://www.yaml.org/spec/#.Document> like "--- #YAML:1.0"
Fields
The rest of the META.yml file is one big YAML mapping <http://www.yaml.org/spec/#.-syntax-mapping-
Mapping->, whose keys are described here.
name
Example: "Module-Build"
The name of the distribution. Often created by taking the "main module" in the distribution and
changing "::" to "-". Sometimes it's completely different, however, as in the case of the libwww-
perl <http://search.cpan.org/author/GAAS/libwww-perl/> distribution.
version
Example: 0.16
The version of the distribution to which the META.yml file refers. This is a mandatory field.
The version is essentially an arbitrary string, but must be only ASCII characters, and strongly
should be of the format integer-dot-digit-digit, i.e. 25.57, optionally followed by underscore-digit-
digit, i.e. "25.57_04".
The standard tools that deal with module distribution (PAUSE, CPAN, etc.) form an identifier for each
distribution by joining the 'name' and 'version' attributes with a dash ("-") character. Tools who
are prepared to deal with distributions that have no version numbers generally omit the dash as well.
license
Example: "perl"
a descriptive term for the licenses ... not authoritative, but must be consistent with licensure
statements in the READMEs, documentation, etc.
The license under which this distribution may be used and redistributed.
Must be one of the following licenses:
perl
The distribution may be copied and redistributed under the same terms as perl itself (this is by
far the most common licensing option for modules on CPAN). This is a dual license, in which the
user may choose between either the GPL or the Artistic license.
gpl The distribution is distributed under the terms of the Gnu General Public License
(<http://www.opensource.org/licenses/gpl-license.php>).
lgpl
The distribution is distributed under the terms of the Gnu Lesser General Public License
(<http://www.opensource.org/licenses/lgpl-license.php>).
artistic
The distribution is licensed under the Artistic License, as specified by the Artistic file in the
standard perl distribution.
bsd The distribution is licensed under the BSD License
(<http://www.opensource.org/licenses/bsd-license.php>).
open_source
The distribution is licensed under some other Open Source Initiative-approved license listed at
<http://www.opensource.org/licenses/>.
unrestricted
The distribution is licensed under a license that is not approved by www.opensource.org
<http://www.opensource.org> but that allows distribution without restrictions.
restrictive
The distribution may not be redistributed without special permission from the author and/or
copyright holder.
license_uri
This should contain a URI where the exact terms of the license may be found.
(change "unrestricted" to "redistributable"?)
distribution_type
Example: "module"
What kind of stuff is contained in this distribution. Most things on CPAN are "module"s (which can
also mean a collection of modules), but some things are "script"s.
This field is basically meaningless, and tools (like Module::Build or MakeMaker) will likely stop
generating it in the future.
private
WTF is going on here?
index_ignore: any application that indexes the contents of distributions (PAUSE, search.cpan.org)
ought to ignore the items (packages, files, directories, namespace hierarchies).
requires
Example:
Data::Dumper: 0
File::Find: 1.03
A YAML mapping <http://www.yaml.org/spec/#.-syntax-mapping-Mapping-> indicating the Perl modules this
distribution requires for proper operation. The keys are the module names, and the values are
version specifications as described in the Module::Build.
Note: the exact nature of the fancy specifications like ">= 1.2, != 1.5, < 2.0" is subject to change.
Advance notice will be given here. The simple specifications like "1.2" will not change in format.
recommends
Example:
Data::Dumper: 0
File::Find: 1.03
A YAML mapping <http://www.yaml.org/spec/#.-syntax-mapping-Mapping-> indicating the Perl modules this
distribution recommends for enhanced operation.
build_requires
Example:
Data::Dumper: 0
File::Find: 1.03
A YAML mapping <http://www.yaml.org/spec/#.-syntax-mapping-Mapping-> indicating the Perl modules
required for building and/or testing of this distribution. These dependencies are not required after
the module is installed.
conflicts
Example:
Data::Dumper: 0
File::Find: 1.03
A YAML mapping <http://www.yaml.org/spec/#.-syntax-mapping-Mapping-> indicating the Perl modules that
cannot be installed while this distribution is installed. This is a pretty uncommon situation.
- possibly separate out test-time prereqs, complications include: can tests be meaningfully preserved
for later running? are test-time prereqs in addition to build-time, or exclusive?
- make official location for installed *distributions*, which can contain tests, etc.
dynamic_config
Example: 0
A boolean flag indicating whether a Build.PL or Makefile.PL (or similar) must be executed, or whether
this module can be built, tested and installed solely from consulting its metadata file. The main
reason to set this to a true value if that your module performs some dynamic configuration (asking
questions, sensing the environment, etc.) as part of its build/install process.
Currently Module::Build doesn't actually do anything with this flag - it's probably going to be up to
higher-level tools like CPAN to do something useful with it. It can potentially bring lots of
security, packaging, and convenience improvements.
generated_by
Example: "Module::Build version 0.16"
Indicates the tool that was used to create this META.yml file. It's good form to include both the
name of the tool and its version, but this field is essentially opaque, at least for the moment.
Ingy's suggestions
short_description
add as field, containing abstract, maximum 80 characters, suggested minimum 40 characters
description
long version of abstract, should add?
maturity
alpha, beta, gamma, mature, stable
author_id, owner_id
categorization, keyword, chapter_id
URL for further information
could default to search.cpan.org on PAUSE
namespaces
can be specified for single elements by prepending dotted-form, i.e.
"com.example.my_application.my_property". Default namespace for META.yml is probably
"org.cpan.meta_author" or something. Precedent for this is Apple's Carbon namespaces, I think.
History
• March 14, 2003 (Pi day) - created version 1.0 of this document.
• May 8, 2003 - added the "dynamic_config" field, which was missing from the initial version.
perl v5.22.1 2020-10-19 CPAN::Meta::History::Meta_1_1(3perl)