fsmpy 1.0.1

Minimal state machine

Minimal state machine

• Free software: BSD license

Usage

import fsm

class MyModel(fsm.FiniteStateMachineMixin):
    """An example to test the state machine.

    Contains transitions to everywhere, nowhere and specific states.
    """

    state_machine = {
        'created': '__all__',
        'pending': ('running',),
        'running': ('success', 'failed'),
        'success': None,
        'failed': ('retry',),
        'retry': ('pending', 'retry'),
    }

    def __init__(self, state):
        """Initialize setting a state."""
        self.state = state

    def current_state(self):
        """Overriden."""
        return self.state

    def on_before_pending(self):
        print("I'm going to a pending state")

In [4]: m = MyModel(state='created')

In [5]: m.change_state('pending')
I'm going to a pending state
Out[5]: 'pending'

In [6]: m.change_state('failed')
---------------------------------------------------------------------------
InvalidTransition                         Traceback (most recent call last)
<ipython-input-6-71d2461eee74> in <module>()
----> 1 m.change_state('failed')

~/pyfsm/src/fsm/fsm.py in change_state(self, next_state, **kwargs)
    90             msg = "The transition from {0} to {1} is not valid".format(previous_state,
    91                                                                        next_state)
---> 92             raise InvalidTransition(msg)
    93
    94         name = 'pre_{0}'.format(next_state)

InvalidTransition: The transition from pending to failed is not valid

There are hooks that can be included before a state transition happens and after.

fsm will look for these functions

pre_<state_name>
post_<state_name>

And will give them any extra argument given to change_state

E.g:

Running m.change_state('pending', name='john') will trigger pre_pending(name='john')

Installation

pip install fsmpy

Documentation

https://pyfsm.readthedocs.org/

Development

To run the all tests run:

tox

Note, to combine the coverage data from all the tox environments run:

Windows	set PYTEST_ADDOPTS=--cov-append tox
Other	PYTEST_ADDOPTS=--cov-append tox

Changelog

1.0.0 (2018-07-03)

• Renamed hooks to pre_<state_name> and post_<state_name>

0.1.3 (2017-15-09)

• Updated docs

• Corrections to code

• ci updated

0.1.0 (2016-04-18)

• First release on PyPI.