pytomaton 1.0

A more convenient and succinct way of expressing state machines in Python

pytomaton: State Machines in Python
=========

Brief
-----
Often, a state machine is a convenient way to implement a stateful protocol, but
they often involve a lot of messy boilerplate for managing how you transition
from one state to the next, or what exactly happens when you enter a state.
`pytomaton` was created to reduce this boilerplate code.

Just as in a theoretical automaton, a `pytomaton.statemachine` has a list of
states, a start state. At any given time, a state machine is in one single
state. The programmer can invoke `statemachine.transition(new_state_name)` to
transition to a new state; when this happens, the state machine checks to see if
there are any actions which are triggered by this transition. Currently, actions
can be triggered by entering a specific state (`on_enter`), or by transitioning
from one specific state to another (`on_transition`). Methods are decorated as
being triggered by transitions, as shown in the example below.

Example
-------

from pytomaton import statemachine, on_transition, on_enter

class ConnectionMachine(statemachine):
states = ['waiting_for_connection', 'waiting_for_ready', 'all_ready']
start_state = 'waiting_for_connection'

def on_connect(self):
self.transition('waiting_for_ready')

@on_transition('waiting_for_connection', 'waiting_for_ready')
def send_ready_prompt(self):
self.broadcast('are you ready?')

def receive_ready_confirm(self):
if self.all_ready():
self.transition('all_ready')

@on_enter('all_ready')
def send_all_ready(self):
self.broadcast('everyone is ready!')

In this example, we define a `ConnectionMachine` that has three states. It
starts in the `waiting_for_connection` state. When a user connects, in
transitions to the `waiting_for_ready` state, which triggers a call to
`send_ready_prompt`. When a user confirms that they're ready, we transition to
the `on_ready` state, which triggers a call to `send_all_ready`.