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|
module ActiveModel
# ==== Examples
#
# class TrafficLight
# include ActiveModel::StateMachine
#
# state_machine do
# state :red
# state :green
# state :yellow
# state :blink
#
# event :change_color do
# transitions :to => :red, :from => [:yellow],
# :on_transition => :catch_runners
# transitions :to => :green, :from => [:red]
# transitions :to => :yellow, :from => [:green]
# end
#
# event :defect do
# transitions :to => :blink, :from => [:yellow, :red, :green]
# end
#
# event :repair do
# transitions :to => :red, :from => [:blink]
# end
# end
#
# def catch_runners
# puts "That'll be $250."
# end
# end
#
# light = TrafficLight.new
# light.current_state # => :red
# light.change_color # => true
# light.current_state # => :green
# light.green? # => true
# light.change_color! # => true
# light.current_state # => :yellow
# light.red? # => false
# light.change_color # => true
# "That'll be $250."
#
#
# * The initial state for TrafficLight is red which is the first state defined.
#
# # Want to know the initial_state?
# TrafficLight.state_machine.initial_state # => :red
#
# * On a succesful transition to red (from yellow), the local +catch_runners+
# method is executed
#
# * The object acts differently depending on its current state, for instance,
# the change_color! method has a different action depending on the current
# color of the light
#
# * Get the possible events for a state
#
# TrafficLight.state_machine.events_for(:red) # => [:change_color, :defect]
# TrafficLight.state_machine.events_for(:blink) # => [:repair]
#
#
# The StateMachine also supports the following features :
#
# * Success callbacks on event transition
#
# event :sample, :success => :we_win do
# ...
# end
#
# * Enter and exit callbacks par state
#
# state :open, :enter => [:alert_twitter, :send_emails], :exit => :alert_twitter
#
# * Guards on transition
#
# event :close do
# # You may only close the store if the safe is locked!!
# transitions :to => :closed, :from => :open, :guard => :safe_locked?
# end
#
# * Setting the initial state
#
# state_machine :initial => :yellow do
# ...
# end
#
# * Named the state machine, to have more than one
#
# class Stated
# include ActiveModel::StateMachine
#
# strate_machine :name => :ontest do
# end
#
# state_machine do
# end
# end
#
# # Get the state of the <tt>:ontest</tt> state machine
# stat.current_state(:ontest)
# # Get the initial state
# Stated.state_machine(:ontest).initial_state
#
# * Changing the state
#
# stat.current_state(:default, :astate) # => :astate
# # But you must give the name of the state machine, here <tt>:default</tt>
#
module StateMachine
autoload :Event, 'active_model/state_machine/event'
autoload :Machine, 'active_model/state_machine/machine'
autoload :State, 'active_model/state_machine/state'
autoload :StateTransition, 'active_model/state_machine/state_transition'
extend ActiveSupport::Concern
class InvalidTransition < Exception
end
module ClassMethods
def inherited(klass)
super
klass.state_machines = state_machines
end
def state_machines
@state_machines ||= {}
end
def state_machines=(value)
@state_machines = value ? value.dup : nil
end
def state_machine(name = nil, options = {}, &block)
if name.is_a?(Hash)
options = name
name = nil
end
name ||= :default
state_machines[name] ||= Machine.new(self, name)
block ? state_machines[name].update(options, &block) : state_machines[name]
end
def define_state_query_method(state_name)
name = "#{state_name}?"
undef_method(name) if method_defined?(name)
class_eval "def #{name}; current_state.to_s == %(#{state_name}) end"
end
end
def current_state(name = nil, new_state = nil, persist = false)
sm = self.class.state_machine(name)
ivar = sm.current_state_variable
if name && new_state
if persist && respond_to?(:write_state)
write_state(sm, new_state)
end
if respond_to?(:write_state_without_persistence)
write_state_without_persistence(sm, new_state)
end
instance_variable_set(ivar, new_state)
else
instance_variable_set(ivar, nil) unless instance_variable_defined?(ivar)
value = instance_variable_get(ivar)
return value if value
if respond_to?(:read_state)
value = instance_variable_set(ivar, read_state(sm))
end
value || sm.initial_state
end
end
end
end
|
