librinci-perl 1.1.43-1 / usr / share / perl5 / Rinci.pod

package Rinci; # just to make PodWeaver happy

# VERSION

1;
# ABSTRACT: Language-neutral metadata for your code entities

__END__

=pod

=encoding UTF-8

=head1 NAME

Rinci - Language-neutral metadata for your code entities

=head1 VERSION

version 1.1.43

=head1 SPECIFICATION VERSION

 1.1

=head1 ABSTRACT

This document describes B<Rinci>, a set of extensible, language-neutral metadata
specifications for your code (functions/methods, variables, packages, classes,
and so on). Rinci allows various helper tools, from code generator to web
middleware to documentation generator to other protocols, to act on your code,
making your life easier as a programmer. Rinci also allows better
interoperability between programming languages. Rinci is geared towards dynamic
scripting languages like Perl, Python, Ruby, PHP, JavaScript, but is not limited
to those languages.

=head1 STATUS

The 1.1 series does not guarantee full backward compatibility between revisions,
so caveat implementor. However, major incompatibility will bump the version to
1.2 or 2.0.

=head1 TERMINOLOGIES

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in RFC 2119.

B<Rinci> is a set of specifications of metadata for your code entities. Each
different type of code entity, like function/method, variable, namespace, etc,
has its own metadata specification.

B<Metadata> is a defhash (see L<DefHash>). Each specification will specify what
B<properties> should be supported. So the L<Rinci::function> specification will
describe metadata for functions/methods, L<Rinci::package> will describe
metadata for namespace/package, and so on.

Rinci defines properties pertaining to documentation (like C<summary>,
C<description>, C<examples>, C<links>), function argument and return value
validation (C<args> and C<result>), dependencies (C<deps>), standardized feature
description (C<features>), also a few conventions/protocols for doing stuffs
like undo (others like callback/progress report will follow). Basically anything
that can describe the code entity. The specification is extensible: you can
define more properties, or more deps, or more features.

Since defhash can contain keys that are ignored (those that start with
underscore, C<_>), extra information can be put here.

=head1 WHAT ARE THE BENEFITS OF RINCI?

By adding Rinci metadata to your code, you can write/use tools to do various
things to your program. Rinci is designed with code generation and function
wrapping in mind. At the time of this writing, in Perl there exists several
tools (mostly modules under L<Perinci> namespace) to do the following:

=over 4

=item * L<Perinci::Sub::Wrapper>

Wrap functions with a single generated function that can do the following:
validate input (using information from the C<args> property), validate return
value (the C<result> property), add execution time-limiting (C<timeout>), add
automatic retries (C<retry>), interactive confirmation, logging, and more.

=item * L<Perinci::Exporter>

A replacement for L<Exporter> or L<Sub::Exporter> if your functions are equipped
with Rinci metadata. Automatically provide export tags (using information in the
C<tags> property). Can automatically wrap functions using Perinci::Sub::Wrapper
when exporting.

=item * Perinci::To::* modules

Convert metadata to various other documents, for example L<Perinci::To::POD> to
generate documentation.

=item * L<Perinci::CmdLine>

L<Riap> command-line client. Call local/remote functions. Automatically convert
command-line options/arguments to function arguments. Generate help/usage
message (for C<--help>). Check dependencies (e.g. you can specify that in order
to run your functions, you need some executables/other functions to exist, an
environment variable being set, and so on), perform bash shell completion (using
L<Perinci::Sub::Complete>).

=item * L<Perinci::Access::HTTP::Server>

A L<PSGI> application (a set of PSGI middlewares, really) to serve metadata and
function call requests over HTTP, according to the L<Riap::HTTP> protocol.

=item * L<Serabi>

An alternative for L<Perinci::Access::HTTP::Server> for REST-style service.

=item * L<Perinci::Use>

Use remote packages and import their functions/variables transparently like you
would use local Perl modules. The remote server can be any Riap-compliant
service, even when implemented in other languages.

=item * C<Perinci::Sub::Gen::*>

Since Rinci metadata are just normal data structure, they can be easily
generated. The Perinci::Sub::Gen::* Perl modules can generate functions as well
as their metadata, for example to access table data (like from a regular array
or from a SQL database).

=back

More tools will be written in the future.

=head1 RINCI VS ...

Some features offered by Rinci (or Rinci tools) are undoubtedly already offered
by your language or existing language libraries. For example, for documentation
Perl already has POD and Python has docstrings. There are numerous libraries for
argument validation in every language. Python has decorators that can be used to
implement various features like argument validation and logging. Perl has
subroutine attributes to stick additional metadata to your subroutines and
variables. And so on.

The benefits that Rinci offer include richer metadata, language neutrality,
extensibility, and manipulability.

B<Richer metadata>. Rinci strives to provide enough metadata for tools to do
various useful things. For example, the C<description> and C<summary> properties
support translations. Argument specification is pretty rich, with a quite
powerful and flexible schema language.

B<Language neutrality>. You can share metadata between languages, including
documentation and rules for argument validation. Perl 6 allows very powerful
argument validation, for example, but it is language-specific. With Rinci you
can easily share validation rules and generate validators in Perl and JavaScript
(and other target languages).

B<Manipulability>. Being a normal data structure, your Rinci metadata is easier
to manipulate (clone, merge, modify, export, what have you) as well as access
(from your language and others). Perl's POD documentation is not accessible from
the language (but Perl 6's Pod and Python docstrings are, and there are
certainly tools to parse POD). On the other hand, Python docstrings are attached
in the same file with the function, while with Rinci you can choose to separate
the metadata into another file more easily.

B<Other things to consider>. If you stack multiple decorators in Python, for
example, it usually results in wrapping your Python function multiple times,
which can add overhead. A single wrapper like L<Perinci::Sub::Wrapper>, on the
other hand, uses a single level of wrapping to minimize subroutine call
overhead.

B<Working together>. There is no reason why Rinci metadata has to compete
against existing features from language/libraries. A code generator for Rinci
metadata can generate code that utilize those features. For example, the
C<timeout> property can be implemented in Python using decorator, if you want.
Rinci basically just provides a way for you to express desired
properties/constraints/behaviours, separate from the implementation. A tool is
free to implement those properties using whatever technique is appropriate.

=head1 SPECIFICATION

Note: Examples are usually written in Perl, but this does not mean they only
apply to a particular language.

=head2 Terminologies

B<Code entities>, or just B<entities> for short, are elements in your code that
can be given metadata. Currently supported entities are function/method,
namespace/package, and variable. Other entities planned to be supported: class,
object, library, application.

=head2 Specification common to all metadata

This section describes specification common to all kinds of Rinci metadata.

B<Where to put the metadata>. The specification does not specify where to put
metadata in: it might be put alongside the code, separated in another source
code, encoded in YAML/JSON, put in database, or whatever. It is up to the
tools/implementations to provide the mechanism. If you use L<Perinci> in Perl,
there is a great deal of flexibility, you basically can do all of the above,
even split the metadata in several files. See its documentation for more
details.

B<Common properties>. Below are properties common to all metadata:

=head3 Property: v => FLOAT (required)

From DefHash. Declare specification version. This property is required. It
should have the value of 1.1. If C<v> is not specified, it is assumed to be 1.0
and metadata is assumed to be the old, Sub::Spec 1.0.x metadata.

Example:

 v => 1.1

=head3 Property: entity_v => STR

Specify entity version (like package or function version). This is version as in
software implementation version, not to be confused with C<v> which is the
metadata specification version (1.1).

Example:

 entity_v => 0.24

In Perl, modules usually put version numbers in package variable called
C<$VERSION>. If not set, tools like L<Perinci::Access::Perl> automatically fills
this property from that variable, to relieve authors from manually setting this
property value.

=head3 Property: default_lang => STR

From DefHash. Specify default language used in the text properties like
C<summary> and C<description>. Default is 'en_US'.

To specify translation texts in other languages, you can use
C<PROPERTY.alt.lang.CODE>, e.g.:

 summary => "Perform the foo ritual",
 "summary.alt.lang.id_ID" => "Laksanakan ritual foo",

=head3 Property: name => STR

From DefHash. The name of the entity. Useful when aliasing entity (and reusing
the metadata) and wanting to find out the canonical/original entity.

Examples:

 name => 'foo'
 name => '$var'  # only in languages where variables have prefix

=head3 Property: summary => STR

From DefHash. A one-line summary. It should be plain text without any markup.
Please limit to around 72 characters.

Example:

 # in variable metadata for $Answer
 summary => 'The answer to the question: what is the meaning of life'

 # in function metadata foo
 summary => 'Perform the foo ritual',

For variable metadata, it should describe what the variable contain. You do not
need to say "Contains ..." or "A variable that ..." since that is redundant;
just say directly the content of the variable (noun). You also do not need to
say what kinds of values the variable should contain, like "An integer, answer
to the ..." or "..., should be between 1..100" since that should go to the
C<schema> property.

For function metadata, it should describe what the function does. Suggestion:
use active, bare infinitive verb like in the example (not "Performs ..."). Avoid
preamble like "This function ..." or "Function to ..." since that is redundant.
Also avoid describing the arguments and its values like "..., accepts a single
integer argument" as that should go to the C<args> property.

To specify translations in other language, use the L<summary.alt.lang.CODE>.
Or change the C<default_lang> property. Examples:

 # default language is 'en_US'
 summary => 'Perform the foo ritual',
 "summary.alt.lang.id_ID" => 'Laksanakan ritual foo',

 # change default language to id_ID, so all summaries are in Indonesian, except
 # when explicitly set otherwise
 default_lang => 'id_ID',
 summary => 'Laksanakan ritual foo',
 "summary.alt.lang.en_US" => 'Perform the foo ritual',

=head3 Property: tags => ARRAY OF (STR OR HASH)

From DefHash. A list of tags, useful for categorization. Can also be used by
tools, e.g. L<Perinci::Exporter> in Perl uses the C<tags> property of the
function metadata as export tags.

Tag can be a simple string or a tag metadata hash.

Example:

 # tag a function as beta
 tags => ['beta']

 # the second tag is a detailed metadata
 tags => ['beta',
          {
              name    => 'category:filtering',
              summary => 'Filtering',
              "summary.alt.lang.id_ID" => 'Penyaringan',
          }
         ]

=head3 Property: description => STR

From DefHash. A longer description text. The text should be in marked up in
format specified by C<text_markup> and is suggested to be formatted to 78
columns.

To avoid redundancy, you should mentioning things that are already expressed as
properties, for example: return value of function (specify it in C<result>
property instead), arguments that the function accepts (C<args>), examples
(C<examples>), function's features (C<features>) and dependencies/requirements
(C<deps>).

For function, description should probably contain a more detailed description of
what the function does (steps, algorithm used, effects and other things of
note).

Example:

 {
     name => 'foo',
     summary => 'Perform the foo ritual',
     description => <<EOT,

 Foo ritual can be performed by humans or machines. This program will perform a
 machine-based ritual using [the best available
 algorithm](http://example.org/foo-with-bar-algo.html).

 Note that you still have to perform foo ritual manually from time to time, just
 to be safe.

 EOT
 }

Like in C<summary>, to specify translations in other language, use the
L<description.alt.lang.CODE> property.

=head3 Property: links => ARRAY OF HASHES

List to related entities or resources. Can be used to generate a SEE ALSO and/or
LINKS sections in documentation. Each link is a defhash with the following keys:

=over 4

=item * uri => STR (required)

URI is used as a common syntax to refer to resources. If URI scheme is not
specified, tools can assume that it is a C<riap> URI (see L<Riap>).

=item * title => STR

A short plaintext title for the link.

=item * description => STR

From DefHash. A longer marked up text description for the link. Suggested to be
formatted to 76 columns.

=item * tags => ARRAY OF (STR OR HASH)

From DefHash. Can be used to categorize or select links. For generating SEE ALSO
sections, use the tag 'see'.

=back

Example:

 # links in the Bar::foo function metadata
 links => [
     {
         url   => "http://example.org/foo-with-bar-algo.html",
         title => "Article describing foo using Bar algorithm",
     },
     {
         url   => "../Bar2/",
         title => "Another implementation of the Bar algorithm",
         tags  => ['see'],
     },
 ],

=head3 Property: x => ANY

From DefHash. This property is used to store extended (application-specific)
attributes, much like the C<X-> prefix in HTTP or email headers. This property
can be used as an alternative to using underscore prefix (e.g. C<_foo>). Some
processing tools strip properties/attributes that begin with underscores, so to
pass extended metadata around, it might be more convenient to use the C<x>
property.

It is recommended that you put an application prefix.

Example:

 "x.myapp.foo" => "some value",

Another example:

 "x.dux.strip_newlines" => 0,

=head2 Entity-specific specifications

Each entity-specific specification is described on a separate subdocument.
Currently these specifications are defined:

=over 4

=item * L<Rinci::function> - Metadata for functions/methods

=item * L<Rinci::package> - Metadata for namespaces/packages

=item * L<Rinci::variable> - Metadata for variables

=item * L<Rinci::result> - Function/method result metadata

=back

These specifications are planned or considered, but not yet defined:

=over 4

=item * L<Rinci::class> - Metadata for classes

=item * L<Rinci::object> - Metadata for objects

=item * L<Rinci::application> - Metadata for applications

=item * L<Rinci::library> - Metadata for libraries

=item * L<Rinci::distribution> - Metadata for software distribution

=item * L<Rinci::language> - Metadata for programming languages

=item * L<Rinci::author> - Metadata for software authors

=item * L<Rinci::project> - Metadata for software projects

=item * L<Rinci::repository> - Metadata for code repository (like git, svn)

=back

=head1 FAQ

=head2 What does Rinci mean?

Rinci is taken from Indonesian word B<perincian> or B<rincian>, meaning:
specification, detail.

=head2 Why use Sah for data schema?

Sah is a flexible and extensible schema language, while still not being
language-specific, making it easy for code generator tools to generate validator
code in various target languages (Perl, Ruby, etc).

=head1 HISTORY

Below is the general history of the project and major changes to the
specifications. For more detailed changes between releases, see the B<Changes>
file in the distribution.

=head1 1.1 (Jan 2012)

To clearly separate specification from implementation, rename specification from
C<Sub::Spec> to C<Rinci> (the namespace C<Perinci> is now used for the Perl
implementation). Support code entities other than functions/methods. Bump
specification version from 1.0 to 1.1 due to several incompatibilities like
changed C<args> and C<result> properties, terminologies, defaults. Versioning
property (C<v>) now required.

=head2 1.0 (Aug 2011)

First release version of Sub::Spec.

=head2 0.x (Feb-Aug 2011)

Series of Sub::Spec drafts.

=head2 Spanel project (2009-2010)

I started using some metadata for API functions, calling them spec and putting
them in %spec instead of in POD, so I can list and grab all the summaries easily
as a single dump for API catalog (instead of having to parse POD from my source
code files). Later on I kept adding more and more stuffs to this, from argument
specification, requirements, and so on.

=head1 SEE ALSO

=head2 Related specifications

L<DefHash>

Sah schema language, L<Sah>

L<Riap>

=head2 Related ideas/concepts

B<.NET attributes>, http://msdn.microsoft.com/en-us/library/z0w1kczw.aspx

B<Python Decorators>, http://www.python.org/dev/peps/pep-0318/ ,
http://wiki.python.org/moin/PythonDecorators

=head2 Other related links

L<Acmeism>, http://www.acmeism.org/

=head1 HOMEPAGE

Please visit the project's homepage at L<https://metacpan.org/release/Rinci>.

=head1 SOURCE

Source repository is at L<https://github.com/sharyanto/perl-Rinci>.

=head1 BUGS

Please report any bugs or feature requests on the bugtracker website L<https://rt.cpan.org/Public/Dist/Display.html?Name=Rinci>

When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.

=head1 AUTHOR

Steven Haryanto <stevenharyanto@gmail.com>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Steven Haryanto.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut