== has_states

+has_states+ adds support for managing states, events, and transitions within a
model.

== Resources

Announcement

* http://www.pluginaweek.org

Wiki

* http://wiki.pluginaweek.org/Has_states

API

* http://api.pluginaweek.org/has_states

Development

* http://dev.pluginaweek.org/browser/trunk/plugins/active_record/has/has_states

Source

* http://svn.pluginaweek.org/trunk/plugins/active_record/has/has_states

== Description

State machines make it dead-simple to manage the behavior of a model.  Too often,
the status of a record is kept by creating multiple boolean columns in the table
and deciding how to behave based on the values in those columns.  This can become
cumbersome and difficult to maintain when the complexity of your models starts to
increase.

+has_states+ simplifies this design by introducing the various parts of a state
machine, including states, events, and transitions.  However, its api is designed
to be similar to ActiveRecord in terms of validations and callbacks, making it
so simple you don't even need to know what a state machine is :)

== Usage

=== Running migrations

To migrate the tables required for has_states, you can either run the
migration from the command line like so:

  rake db:migrate:plugins PLUGIN=has_states

or (more ideally) generate a migration file that will integrate into your main
application's migration path:

  ruby script/generate plugin_migration has_states

== Testing

Before you can run any tests, the following gems must be installed:
* plugin_test_helper[http://wiki.pluginaweek.org/Plugin_test_helper]
* dry_validity_assertions[http://wiki.pluginaweek.org/Dry_validity_assertions]

== Tools

Jean Bovet - {Visual Automata Simulator}[http://www.cs.usfca.edu/~jbovet/vas.html].
This is a great tool for "simulating, visualizing and transforming finite state
automata and Turing Machines".  This tool can help in the creation of states and
events for your models.  It is cross-platform, written in Java.

== Dependencies

This plugin depends on the presence of the following plugins:
* class_associations[http://wiki.pluginaweek.org/Class_associations]
* custom_callbacks[http://wiki.pluginaweek.org/Custom_callbacks]
* dry_transaction_rollbacks[http://wiki.pluginaweek.org/Dry_transaction_callbacks]
* eval_call[http://wiki.pluginaweek.org/Eval_call]

This plugin is also plugin+.  That means that it contains a slice of an
application, such as models and migrations.  To test or use a plugin+, you
must have the following plugins/gems installed:
* plugin_dependencies[http://wiki.pluginaweek.org/Plugin_dependencies]
* loaded_plugins[http://wiki.pluginaweek.org/Loaded_plugins]
* appable_plugins[http://wiki.pluginaweek.org/Appable_plugins]
* plugin_migrations[http://wiki.pluginaweek.org/Plugin_migrations]

Instead of installing each individual plugin+ feature, you can install them all
at once using the plugins+[http://wiki.pluginaweek.org/Plugins_plus] meta package,
which contains all additional features.

== References

* Scott Barron - acts_as_state_machine[http://elitists.textdriven.com/svn/plugins/acts_as_state_machine]