finite 0.1.0

Yet another finite state automaton

Yet another finite state automaton for python.

Introduction

The emphasis is on a simple, readable configuration:

automata1:
  start: Occupied
  states:
    Occupied: {}
    Alarmed: {}
  transitions:
    Occupied->Alarmed:
      when: house.presence.empty
    Occupied->Alarmed:
      when: house.presence.occupied

It’s particularly suited to home automation (my use case).

Example

For an example of using finite for home automation, see: test/test1.dfa.

Configuration

The configuration format is yaml.

Each automata has a start state, a set of states and a set of transitions:

automata1:
    start: Occupied
    states:
        Occupied:
            {}
        Alarmed:
            {}
    transitions:
        Occupied->Alarmed:
            when: house.presence.empty
        Occupied->Alarmed:
            when: house.presence.occupied

Transitions may have actions associated with them:

Occupied->Alarmed:
    when: house.presence.empty
    actions:
    - speak('Alarm activated')

These callbacks are called on the ‘callback’ object passed when make_world.

A yaml file may list multiple automaton:

automata1:
    start: State1
    states: ...
    transitions: ...

automata2:
    start: State2
    states: ...
    transitions: ...

Code

Example:

from finite import dfa

# create a callback
class Callback(object):
    def speak(self, msg):
        # do some speaking
        pass
callback = Callback()

# create automaton
worlds = dfa.Worlds()
automatons = dfa.Loader.load_file('my.dfa')
for aut in automatons:
    world = aut.make_world(callback)
    self.worlds.add(world)

# trigger a state change
ev = dfa.Event('house.presence.empty', True)
worlds.process(ev)

Changelog

0.1.0

• First release