NAME

Data::Schema::Manual::Plugin

VERSION

version 0.136

OVERVIEW

This document is explains how to write plugins for Data::Schema.

NAME

Data::Schema::Manual::Plugin - Writing plugins for Data::Schema

INTRODUCTION

Any object can become a plugin as long as it satisfies these requirements.

1. It has a validator([$validator]) method to retrieve/set the validator property.

2. has handle_*() methods according to which functionalities it wants to supply.

HANDLE_*() METHOD CONVENTION

The convention for handle_*() methods is to return 0 if fail, 1 if succeed, or -1 if decline. If a plugin decline to handle some event, the next plugin in the list will be tried.

AVAILABLE HANDLE_*() METHODS

handle_unknown_type($type)

This is called by DS in the validation process when encountering an unknown type to give a chance for plugins to load new types. Used for example by DSP::LoadSchema::YAMLFile to load schemas from YAML files.

handle_type($data, $attr_hashes)

This is for type handler. Called by DS's validate() to validate a type. See the implementation in, for example, DST::Base.

handle_pre_check_attrs($data)

This is for type handler. Called by DST::Base's handle_type() method to allow subclass type handlers to do some checks before evaluating type attributes.

handle_attr_NAME($data, $arg)

This is for type handler. Called by DST::Base's handle_type() method to allow subclass type handlers to do attribute checking. For example, if attribute min is encountered in the schema, handle_attr_min will be called.

DIFFERENCES FROM TYPE HANDLER

Type handler can be thought of as yet another plugin. The differences are:

1. It is registered via $validator->register_type() instead of $validator->register_plugin().

2. It will only be involved in type checking during validation process. Specifically it will only handle:

 handle_pre_check_attrs()
 handle_type()
 handle_attr_*()

3. You also need to supply cmp().

USING YOUR NEW PLUGIN

To use your new plugin, register it via:

 $validator->register_plugin('Your::Class');

or

 $validator->register_plugin($your_obj);

SEE ALSO

Data::Schema::Type::Base.

AUTHOR

  Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2009 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.