AASM - Ruby state machines

This package contains AASM, a library for adding finite state machines to Ruby classes.

AASM started as the acts_as_state_machine plugin but has evolved into a more generic library that no longer targets only ActiveRecord models.

AASM has the following features:

• States
• Machines
• Events
• Transitions

New Callbacks

The callback chain & order on a successful event looks like:

  oldstate:exit*
  event:before
  __find transition, if possible__
  transition:on_transition*
  oldstate:before_exit
  newstate:before_enter
  newstate:enter*
  __update state__
  event:success*
  oldstate:after_exit
  newstate:after_enter
  event:after
  obj:aasm_event_fired*

  (*) marks old callbacks

Download

The latest AASM can currently be pulled from the git repository on github.

• github.com/rubyist/aasm/tree/master

Installation

From gemcutter

  % sudo gem install gemcutter
  % sudo gem tumble
  % sudo gem install aasm

From GitHub hosted gems (only older releases are available)

  % sudo gem sources -a http://gems.github.com # (you only need to do this once)
  % sudo gem install rubyist-aasm

Building your own gems

  % rake gemspec
  % rake build
  % sudo gem install pkg/aasm-2.1.gem

Simple Example

Here’s a quick example highlighting some of the features.

  class Conversation
    include AASM

    aasm_column :current_state # defaults to aasm_state

    aasm_initial_state :unread

    aasm_state :unread
    aasm_state :read
    aasm_state :closed

    aasm_event :view do
      transitions :to => :read, :from => [:unread]
    end

    aasm_event :close do
      transitions :to => :closed, :from => [:read, :unread]
    end
  end

A Slightly More Complex Example

This example uses a few of the more complex features available.

  class Relationship
    include AASM

    aasm_column :status

    aasm_initial_state Proc.new { |relationship| relationship.strictly_for_fun? ? :intimate : :dating }

    aasm_state :dating,   :enter => :make_happy,        :exit => :make_depressed
    aasm_state :intimate, :enter => :make_very_happy,   :exit => :never_speak_again
    aasm_state :married,  :enter => :give_up_intimacy,  :exit => :buy_exotic_car_and_wear_a_combover

    aasm_event :get_intimate do
      transitions :to => :intimate, :from => [:dating], :guard => :drunk?
    end

    aasm_event :get_married do
      transitions :to => :married, :from => [:dating, :intimate], :guard => :willing_to_give_up_manhood?
    end

    def strictly_for_fun?; end
    def drunk?; end
    def willing_to_give_up_manhood?; end
    def make_happy; end
    def make_depressed; end
    def make_very_happy; end
    def never_speak_again; end
    def give_up_intimacy; end
    def buy_exotic_car_and_wear_a_combover; end
  end

Other Stuff

Warranty

This software is provided “as is” and without any express or implied warranties, including, without limitation, the implied warranties of merchantibility and fitness for a particular purpose.