state_machine

https://github.com/pluginaweek/state_machine

Ruby

Adds support for creating state machines for attributes on any Ruby class

StateMachine::Event#transition

Creates a new transition that determines what to change the current state
to when this event fires.

Since this transition is being defined within an event context, you do
*not* need to specify the <tt>:on</tt> option for the transition.  For
example:

 state_machine do
   event :ignite do
     transition :parked => :idling, :idling => same, :if => :seatbelt_on? # Transitions to :idling if seatbelt is on
     transition all => :parked, :unless => :seatbelt_on?                  # Transitions to :parked if seatbelt is off
   end
 end

See StateMachine::Machine#transition for a description of the possible
configurations for defining transitions.

Source | Google | Stack overflow

Edit

git clone [email protected]:pluginaweek/state_machine.git

cd state_machine

open lib/state_machine/event.rb

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-StateMachine--Event-transition-for-pr

# Commit to git

git add lib/state_machine/event.rbgit commit -m "better docs for StateMachine::Event#transition"

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-StateMachine--Event-transition-for-pr

hub pull-request

# Celebrate!