pysm - Python State Machine

Versatile and flexible Python State Machine library.

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Implement simple and complex state machines

It can do simple things like this:

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Or somewhat more complex like that:

.. image:: https://cloud.githubusercontent.com/assets/3026621/15031148/ad955f06-124e-11e6-865e-c7e3340f14cb.png

Python State Machine

The State Pattern <https://en.wikipedia.org/wiki/State_pattern>_ solves many problems, untangles the code and saves one's sanity. Yet.., it's a bit rigid and doesn't scale. The goal of this library is to give you a close to the State Pattern simplicity with much more flexibility. And, if needed, the full state machine functionality, including FSM <https://en.wikipedia.org/wiki/Finite-state_machine>_, `HSM <https://en.wikipedia.org/wiki/UML_state_machine

Hierarchically_nestedstates>`, `PDA

https://en.wikipedia.org/wiki/Pushdown_automaton`_ and other tasty things.

Goals

Provide a State Pattern-like behavior with more flexibility (see Documentation <http://pysm.readthedocs.io/en/latest/examples.html>_ for examples)
Be explicit and don't add any magic code to objects that use pysm
Handle directly any kind of event or input (not only strings) - parsing strings is cool again!
Keep it simple, even for someone who's not very familiar with the FSM terminology

Features

Finite State Machine (FSM)
Hierarchical State Machine (HSM) with Internal/External/Local transitions
Pushdown Automaton (PDA)
Transition callbacks - action, before, after
State hooks - enter, exit, and other event handlers
Entry and exit actions are associated with states, not transitions
Events may be anything as long as they're hashable
States history and transition to previous states
Conditional transitions (if/elif/else-like logic)
Explicit behaviour (no method or attribute is added to the object containing a state machine)
No need to extend a class with State Machine class (composition over inheritance)
Fast (even with hundreds of transition rules)
Not too many pythonisms, so that it's easily portable to other languages (ie. JavaScript <https://github.com/pgularski/smjs>_).
Micropython support

Installation

Install pysm from PyPI <https://pypi.python.org/pypi/pysm/>_::

pip install pysm

or clone the Github pysm repository <https://github.com/pgularski/pysm/>_::

git clone https://github.com/pgularski/pysm
cd pysm
python setup.py install

Documentation

Read the docs for API documentation and examples - http://pysm.readthedocs.io/

See Unit Tests to see it working and extensively tested.

Micropython support

The library works with pyboards!::

import upip upip.install('upysm')

pgularski / pysm

readme