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CPAN::Meta::History::Meta_1_2(3User Contributed Perl DocumentatCPAN::Meta::History::Meta_1_2(3pm)

NAME
CPAN::Meta::History::Meta_1_2 - Version 1.2 metadata specification for META.yml

PREFACE
This is a historical copy of the version 1.2 specification for META.yml files, copyright
by Ken Williams and licensed under the same terms as Perl itself.

Modifications from the original:

· Various spelling corrections

· Include list of valid licenses from Module::Build 0.2611 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.

SYNOPSIS
--- #YAML:1.0
name: Module-Build
abstract: Build and install Perl modules
version: 0.20
author:
- Ken Williams <kwilliams AT cpan.org>
license: perl
distribution_type: module
requires:
Config: 0
Cwd: 0
Data::Dumper: 0
ExtUtils::Install: 0
File::Basename: 0
File::Compare: 0
File::Copy: 0
File::Find: 0
File::Path: 0
File::Spec: 0
IO::File: 0
perl: 5.005_03
recommends:
Archive::Tar: 1.00
ExtUtils::Install: 0.3
ExtUtils::ParseXS: 2.02
Pod::Text: 0
YAML: 0.35
build_requires:
Test: 0
urls:
license: http://dev.perl.org/licenses/
meta-spec:
version: 1.2
url: http://module-build.sourceforge.net/META-spec-v1.2.html
generated_by: Module::Build version 0.20

DESCRIPTION
This document describes version 1.2 of the META.yml specification.

The META.yml file describes important properties of contributed Perl distributions such as
the ones found on CPAN. It is typically created by tools like Module::Build,
Module::Install, and ExtUtils::MakeMaker.

The fields in the META.yml file are meant to be helpful for people maintaining module
collections (like CPAN), for people writing installation tools (like CPAN.pm or CPANPLUS),
or just for people who want to know some stuff about a distribution before downloading it
and starting to install it.

Note: The latest stable version of this specification can always be found at
<http://module-build.sourceforge.net/META-spec-current.html>, and the latest development
version (which may include things that won't make it into the stable version can always be
found at <http://module-build.sourceforge.net/META-spec-blead.html>.

FORMAT
META.yml files are written in the YAML format (see <http://www.yaml.org/>).

See the following links to learn why we chose YAML instead of, say, XML or Data::Dumper:

· Module::Build design plans
<http://www.nntp.perl.org/group/perl.makemaker/2002/04/msg407.html>

· Not keen on YAML <http://www.nntp.perl.org/group/perl.module-
authors/2003/11/msg1353.html>

· META Concerns <http://www.nntp.perl.org/group/perl.module-
authors/2003/11/msg1385.html>

TERMINOLOGY
distribution
This is the primary object described by the META.yml specification. In the context of
this document it usually refers to a collection of modules, scripts, and/or documents
that are distributed for other developers to use.

module
This refers to a reusable library of code typically contained in a single file.
Currently, we primarily talk of perl modules, but this specification should be open
enough to apply to other languages as well (ex. python, ruby).

VERSION SPECIFICATIONS
Some fields require a version specification (ex. "requires", "recommends",
"build_requires", etc.). This section details the version specifications that are
currently supported.

If a single version is listed, then that version is considered to be the minimum version
supported.

If 0 is given as the version number, then any version is supported.

Additionally, for more complicated requirements, the specification supports a list of
versions, each of which may be optionally preceded by a relational operator.

Supported operators include < (less than), <= (less than or equal), > (greater than), >=
(greater than or equal), == (equal), and != (not equal).

If a list is given then it is evaluated from left to right so that any specifications in
the list that conflict with a previous specification are overridden by the later.

Examples:

>= 1.2, != 1.5, < 2.0

Any version from version 1.2 onward, except version 1.5, that also precedes version 2.0.

HEADER
The first line of a META.yml file should be a valid YAML document header like "---
#YAML:1.0".

FIELDS
The rest of the META.yml file is one big YAML mapping whose keys are described here.

meta-spec
Example:

meta-spec:
version: 1.2
url: http://module-build.sourceforge.net/META-spec-v1.2.html

(Spec 1.1) [required] {URL} This field indicates the location of the version of the
META.yml specification used.

name
Example:

name: Module-Build

(Spec 1.0) [required] {string} The name of the distribution which is 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 distribution (see
<http://search.cpan.org/author/GAAS/libwww-perl/>).

version
Example:

version: 0.20

(Spec 1.0) [required] {version} The version of the distribution to which the META.yml file
refers.

abstract
Example:

abstract: Build and install Perl modules.

(Spec 1.1) [required] {string} A short description of the purpose of the distribution.

author
Example:

author:
- Ken Williams <kwilliams AT cpan.org>

(Spec 1.1) [required] {list of strings} A YAML sequence indicating the author(s) of the
distribution. The preferred form is author-name <email-address>.

license
Example:

license: perl

(Spec 1.0) [required] {string} 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.

distribution_type
Example:

distribution_type: module

(Spec 1.0) [optional] {string} 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.

Unfortunately this field is basically meaningless, since many distributions are hybrids of
several kinds of things, or some new thing, or subjectively different in focus depending
on who's using them. Tools like Module::Build and MakeMaker will likely stop generating
this field.

requires
Example:

requires:
Data::Dumper: 0
File::Find: 1.03

(Spec 1.0) [optional] {map} A YAML 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 Module::Build for the "requires" parameter.

recommends
Example:

recommends:
Data::Dumper: 0
File::Find: 1.03

(Spec 1.0) [optional] {map} A YAML mapping indicating the Perl modules this distribution
recommends for enhanced operation.

ALTERNATIVE: It may be desirable to present to the user which features depend on which
modules so they can make an informed decision about which recommended modules to install.

Example:

optional_features:
- foo:
description: Provides the ability to blah.
requires:
Data::Dumper: 0
File::Find: 1.03
- bar:
description: This feature is not available on this platform.
excludes_os: MSWin32

(Spec 1.1) [optional] {map} A YAML sequence of names for optional features which are made
available when its requirements are met. For each feature a description is provided along
with any of "requires", "build_requires", "conflicts", "requires_packages", "requires_os",
and "excludes_os" which have the same meaning in this subcontext as described elsewhere in
this document.

build_requires
Example:

build_requires:
Data::Dumper: 0
File::Find: 1.03

(Spec 1.0) [optional] {map} A YAML 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:

conflicts:
Data::Dumper: 0
File::Find: 1.03

(Spec 1.0) [optional] {map} A YAML mapping indicating the Perl modules that cannot be
installed while this distribution is installed. This is a pretty uncommon situation.

dynamic_config
Example:

dynamic_config: 0

(Spec 1.0) [optional] {boolean} A boolean flag indicating whether a Build.PL or
Makefile.PL (or similar) must be executed when building this distribution, or whether it
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.

If this field is omitted, it defaults to 1 (true).

private
(Deprecated) (Spec 1.0) [optional] {map} This field has been renamed to "no_index". See
below.

provides
Example:

provides:
Foo::Bar:
file: lib/Foo/Bar.pm
version: 0.27_02
Foo::Bar::Blah:
file: lib/Foo/Bar/Blah.pm
Foo::Bar::Baz:
file: lib/Foo/Bar/Baz.pm
version: 0.3

(Spec 1.1) [optional] {map} A YAML mapping that describes all packages provided by this
distribution. This information can be (and, in some cases, is) used by distribution and
automation mechanisms like PAUSE, CPAN, and search.cpan.org to build indexes saying in
which distribution various packages can be found.

When using tools like Module::Build that can generate the "provides" mapping for your
distribution automatically, make sure you examine what it generates to make sure it makes
sense - indexers will usually trust the "provides" field if it's present, rather than
scanning through the distribution files themselves to figure out packages and versions.
This is a good thing, because it means you can use the "provides" field to tell the
indexers precisely what you want indexed about your distribution, rather than relying on
them to essentially guess what you want indexed.

no_index
Example:

no_index:
file:
- My/Module.pm
dir:
- My/Private
package:
- My::Module::Stuff
namespace:
- My::Module::Stuff

(Spec 1.1) [optional] {map} A YAML mapping that describes any files, directories,
packages, and namespaces that are private (i.e. implementation artifacts) that are not of
interest to searching and indexing tools. This is useful when no "provides" field is
present.

(Note: I'm not actually sure who looks at this field, or exactly what they do with it.
This spec could be off in some way from actual usage.)

file

(Spec 1.1) [optional] Exclude any listed file(s).

dir

(Spec 1.1) [optional] Exclude anything below the listed directory(ies).

package

(Spec 1.1) [optional] Exclude the listed package(s).

namespace

(Spec 1.1) [optional] Excludes anything below the listed namespace(s), but not the listed
namespace(s) its self.

keywords
Example:

keywords:
- make
- build
- install

(Spec 1.1) [optional] {list} A sequence of keywords/phrases that describe this
distribution.

resources
Example:

resources:
license: http://dev.perl.org/licenses/
homepage: http://sourceforge.net/projects/module-build
bugtracker: http://rt.cpan.org/NoAuth/Bugs.html?Dist=Module-Build
MailingList: http://lists.sourceforge.net/lists/listinfo/module-build-general

(Spec 1.1) [optional] {map} A mapping of any URL resources related to this distribution.
All-lower-case keys, such as "homepage", "license", and "bugtracker", are reserved by this
specification, as they have "official" meanings defined here in this specification. If
you'd like to add your own "special" entries (like the "MailingList" entry above), use at
least one upper-case letter.

The current set of official keys is:

homepage
The official home of this project on the web.

license
An URL for an official statement of this distribution's license.

bugtracker
An URL for a bug tracker (e.g. Bugzilla or RT queue) for this project.

generated_by
Example:

generated_by: Module::Build version 0.20

(Spec 1.0) [required] {string} 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. If META.yml was generated by hand, it is
suggested that the author be specified here.

[Note: My meta_stats.pl script which I use to gather statistics regarding META.yml usage
prefers the form listed above, i.e. it splits on /\s+version\s+/ taking the first field as
the name of the tool that generated the file and the second field as version of that tool.
RWS]