Consider the following class definition:
class Door acts_as_state_machine :initial => :open state :closed state :open event :lock do transitions :from => :open, :to => closed end event :unlock do transitions :from => :closed, :to => open end end
Now, what is wrong with this script?
door = Door.new door.lock! #=> closes the door door.lock! #=> doesn't do anything. door is already closed
The script should produce an error because the _lock_event does not have a valid transition when the door is already in the _closed_state. Instead, the current _acts_as_state_machine_plugin quietly returns _false_if there is no valid transition. That definitely isn’t what I expected and seriously took me several hours to track down this mysterious behavior.
I have published [a fork of the acts_as_state_machine_project](http://github.com/wireframe/acts_as_state_machine/tree/master) which _correctly raises exceptions if there are no valid transitions available. The code change is very minor if you want to apply a patch to your own install.
There’s an entire rant just ripe for the picking, but I’ll save that for another time. For now, I’ve “scratched my own itch” and have made a library work much more intuitively for me. I’m happy… =)