CPAN::...eta_1_1(3perl) Perl Programmers Reference GuideCPAN::...eta_1_1(3perl)
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 and licensed under the same terms as
Perl itself.
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, with minor updates to text and links to
reflect versions at the time of publication.
• Fixed some dead links to point to active resources.
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://www.nntp.perl.org/group/perl.makemaker/2002/04/msg406.html> on
the MakeMaker mailing list.
The first line of a META.yml file should be a valid YAML document header
<http://yaml.org/spec/history/2002-10-31.html#syntax-document> like "---
#YAML:1.0"
Fields
The rest of the META.yml file is one big YAML mapping
<http://yaml.org/spec/history/2002-10-31.html#syntax-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 version 1 or the
Artistic version 1 license.
gpl The distribution is distributed under the terms of the GNU
General Public License version 2
(<http://opensource.org/licenses/GPL-2.0>).
lgpl
The distribution is distributed under the terms of the GNU
Lesser General Public License version 2
(<http://opensource.org/licenses/LGPL-2.1>).
artistic
The distribution is licensed under the Artistic License version
1, as specified by the Artistic file in the standard perl
distribution
(<http://opensource.org/licenses/Artistic-Perl-1.0>).
bsd The distribution is licensed under the BSD 3-Clause License
(<http://opensource.org/licenses/BSD-3-Clause>).
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://yaml.org/spec/history/2002-10-31.html#syntax-
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 documentation for
Module::Build's "requires" parameter.
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://yaml.org/spec/history/2002-10-31.html#syntax-
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://yaml.org/spec/history/2002-10-31.html#syntax-
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://yaml.org/spec/history/2002-10-31.html#syntax-
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.pm 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.
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