state_machine

https://github.com/pluginaweek/state_machine

Ruby

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

StateMachine::StateContext#transition

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

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

  state_machine do
    state :parked do
      transition :to => :idling, :on => [:ignite, :shift_up]                          # Transitions to :idling
      transition :from => [:idling, :parked], :on => :park, :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/state_context.rb

Contribute

# Make a new branch

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

# Commit to git

git add lib/state_machine/state_context.rbgit commit -m "better docs for StateMachine::StateContext#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--StateContext-transition-for-pr

hub pull-request

# Celebrate!