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
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.
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. See
Module::Build for the list of valid options.
- 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.