farc

Framework for Asyncio/Actor/AHSM Run-to-completion Concurrency written in Python3. In other words, a cheap knock-off of QP that uses Python3 coroutines. This book describes QP and how to program statecharts(a.k.a. hierarchical state machines).

This framework has fewer than 1000 LOC. It allows the programmer to create highly-concurrent programs by using a message-passing system and run-to-completion message handlers within a state-machine architecture. With these tools, complex, asynchronous operations are decomposed into managable chunks of code.

Known Issue: On windows, Ctrl+C is supressed by asyncio event loop's run_forever() (bug report). The workaround is to inject an event to awake the event loop.

Note: This project used to be called "pq" but that name was taken in PyPI, so I renamed to farc (ugh).

Code Repository

https://github.com/dwhall/farc

Release History

2020/11/07 0.2.0

• BREAKS API: Removed initEvent argument from Ahsm.start()
• BREAKS API: Renamed camel-case procedures with underscores
• BREAKS API: Eliminated @staticmethod and use of "me"
• BREAKS API: Removed VcdSpy (debug helper) class from default namespace
• Serialize Event values using pickle. This might lead to a runtime error for some.
• call Framework.run() as soon as possible when an event is posted to AHSM (Max Peng).
• Reimplement HSM algorithm and include hsm_test (Sze Tan)
• Consolidated all files into __init__.py

2019/05/15 0.1.1

• Removed 'initialState' argument from farc.Hsm() constructor; framework now expects Hsm/Ahsm classes to have 'initial()' method.
• Made state methods private in examples to demonstrate a best-practice.
• Created farc.Framework.run_forever() helper function.
• Misc comment and doctring improvements

2018/10/09 0.1.0 Initial release