fsm

FSM is a simple finite state machine

Usage

class Water
  include FSM
  # The state machine is specified as a block in define_fsm.
  define_fsm do
    # now define all the states
    # you can add :enter / :exit callbacks (callback can be a String, Symbol or Proc)
    # these callbacks are triggered on any transition from/to this state

    state(:gas)
    state(:liquid)
    state(:solid, :enter => :on_enter_solid, :exit => :on_exit_solid)

    # define all valid transitions (arguments are name of transition, from state name, to state name)
    # you can define callbacks which are called only on this transition
    transition(:heat_up, :solid, :liquid, :event => :liquified)
    transition(:heat_up, :liquid, :gas)     # look mam.... two transitions with same name
    transition(:cool_down, :gas, :liquid)
    transition(:cool_down, :liquid, :solid)

    # define the attribute which is used to store the state (defaults to :state)
    state(:state_of_material)

    # define the initial state (defaults to the first state defined - :gas in this sample)
    initial(:liquid)
  end

  private
  # callbacks here...
  def ...
end

# then you can call these methods
w = Water.new
w.heat  # the name of the transition is the name of the method
w.reachable_state_names
w.available_transition_names
w.cool_down # again... it's the name of the transition
w.state_of_material

Graphviz / Dot format

FSM supports the dot format of graphviz (http://www.graphviz.org/). If you have the graphviz tools installed (the dot executable must be on the path) then you can export a graph to png like this # Export to water.png in the current dir Water.dot
# Export in another format. (see graphviz documentation for supported file formats) Water.dot(:format => :foo) # Change the extension (defaults to the format) Water.dot(:format => :jpg, :extension => :jpeg) # Specify a custom file Water.dot(:outfile => '/afile.png')

fsm

Usage

Graphviz / Dot format

Copyright