META-spec - Specification for META.yml documents
--- #YAML:1.0 name: Module-Build abstract: Build and install Perl modules version: 0.20 author: - Ken Williams <kwilliams@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
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.
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:
http://nntp.x.perl.org/group/perl.makemaker/406
Not keen on YAML META Concerns
Some fields require a version specification (ex. requires, recommends, build_requires, etc.). This section details the version specications 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 preceeded 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 overriden by the later.
Examples:
>= 1.2, != 1.5, < 2.0
Any version from version 1.2 onward, except version 1.5, that also preceeds version 2.0.
The first line of a META.yml file should be a valid YAML document
header like "--- #YAML:1.0".
The rest of the META.yml file is one big YAML mapping whose keys are described here.
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.
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 libww-perl distribution (see http://search.cpan.org/author/GAAS/libwww-perl/).
Example:
version: 0.20
(Spec 1.0) [required] {version} The version of the distribution to which the META.yml file refers.
Example:
abstract: Build and install Perl modules.
(Spec 1.1) [required] {string} A short description of the purpose of the distribution.
Example:
author:
- Ken Williams <kwilliams@cpan.org>
(Spec 1.1) [required] {list of strings} A YAML sequence indicating the author(s) of the
distribution. The prefered form is author-name <email-address>.
Example:
license: perl
(Spec 1.0) [required] {string} The license under which this distribution may be used and redistributed. See the Module::Build manpage for the list of valid options.
Example:
distribution_type: module
(Spec 1.0) [optional] {string} What kind of stuff is contained in this
distribution. Most things on CPAN are modules (which can also mean
a collection of modules), but some things are scripts.
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.
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 the Module::Build manpage for the ``requires'' parameter.
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.
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.
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.
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).
(Deprecated) (Spec 1.0) [optional] {map} This field has been renamed to no_index. See below.
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.
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.)
(Spec 1.1) [optional] Exclude any listed file(s).
(Spec 1.1) [optional] Exclude anything below the listed directory(ies).
(Spec 1.1) [optional] Exclude the listed package(s).
(Spec 1.1) [optional] Excludes anything below the listed namespace(s),
but not the listed namespace(s) its self.
Example:
keywords:
- make
- build
- install
(Spec 1.1) [optional] {list} A sequence of keywords/phrases that describe this distribution.
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:
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]
CPAN, http://www.cpan.org/
CPAN.pm, http://search.cpan.org/author/ANDK/CPAN/
CPANPLUS, http://search.cpan.org/author/KANE/CPANPLUS/
Data::Dumper, http://search.cpan.org/author/ILYAM/Data-Dumper/
ExtUtils::MakeMaker, http://search.cpan.org/author/MSCHWERN/ExtUtils-MakeMaker/
Module::Build, http://search.cpan.org/author/KWILLIAMS/Module-Build/
Module::Install, http://search.cpan.org/author/KWILLIAMS/Module-Install/
YAML, http://www.yaml.org/
authored_by to author, since that's always been what
it's actually called in actual META.yml files.
Added the ``=='' operator to the list of supported version-checking
operators.
Noted that the distribution_type field is basically meaningless,
and shouldn't really be used.
Clarified dynamic_config a bit.
CPAN::META::Specification, since that implies a
module that doesn't actually exist.