Switcher is lightweight event-driven state machine.
class Package include Switcher::Object def initialize(weight) @sent_weight = weight.to_f @tracking_number = nil end switcher :delivery do state :requested do on :send, switch_to: :sent do |ev, num| @tracking_number = num end end state :sent do before :receive, call: :check_number on :receive do |ev, number, weight| if weight < (@weight - 0.3) ev.switch_to :stolen else ev.switch_to :received end end after :receive do |ev| unpack if delivery_received? end on :miss, switch_to: :missed end state :received state :stolen state :missed end def check_number(ev, number, weight) ev.stop if number.to_s != @tracking_number end def unpack puts "TADA!" end end package = Package.new(4.2) package.delivery # => :requested package.can_send? # => true package.send! "AB123456CD" package.delivery # => :sent package.receive!(3.5, "CD654321AB") package.delivery # => :sent package.receive!(4.1, "AB123456CD") # > TADA! package.delivery # => :received package.delivery_prev # => :sent package.delivery_received? # => true package.can_miss? # => false
Usage with Active Record:
class User < ActiveRecord::Base include Switcher::ActiveRecord switcher :membership do state :guest do on :approve, switch_to: :member end state :member do on :ban, switch_to: :banned do |ev, reason| ev.stop unless reason ban_reason = reason end end state :banned do on :unban, switch_to: :member after :unban do ban_reason = nil end end end end user = User.find(5) user.ban! "Stupid bastard" user.membership # => :banned user.save
- 1.8 compat
- Events without state
- Ability to define validations, associations etc. in state (ability to call static methods from object)
The modified MIT license
Copyright (c) 2012 Andrey Savchenko
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
- The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
- Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.