hierarchical-state-machine 1.0.16

This python library provides an easy-to-learn and easy-to-use API for using Hierarchical State Machines in your project. The state machine is defined using a basic JSON string, and includes convenience timers.

Crystal Clear Design's Hierarchical State Machine for Python

hierarchical_state_machine

This python library provides an easy-to-learn and easy-to-use API for using Hierarchical State Machines in your project. The state machine is defined using a basic JSON string, and includes convenience timers.

• Source code: https://github.com/dantebbs/hierarchical_state_machine

Simplest Example

The Blinky Light

Countdown Example

Fireworks

A More Involved Example

A Hierarchical State Machine Implementing a Simple Crosswalk Controller

1. Get the location of the examples: python -m pip show hierarchical_state_machine
2. Go to the example folder: cd <site-packages>/hierarchical_state_machine/example/pedestrian_crosswalk/
3. Look at the state machine diagram: hierarchical_example_pedestrian_crosswalk_signaler.pdf
4. Execute and follow along: python crosswalk_light_simulator.py
5. Press the b button to request a crossing.
6. Press the Esc button to exit the simulation.

A Tutorial

Here are details about creating a hierarchical state machine in python.

Components of a State Machine

--Events - Are user inputs, timeouts, code-generated, or an output of another state machine. --States - A state machine waits in a state until an event or condition causes a transition to another state. --Transitions - Are paths gated by events and/or conditions, to go to another state. --Actions - Are behaviors (i.e. callbacks) evoked as a side-effect of a transition.

Creating a State

Each state contains the following optional elements: entry A list of callback functions that will be invoked each time the state is entered. exit A list of callback functions that will be invoked each time the state is exited. tran A list of transitions which will be followed when conditions are met.