asyncframes 1.1.1

Coroutines for everyone

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asyncframes is a coroutine library for Python and a reference implementation for the Frame Hierarchy Programming Model (FHM). The goal of FHM is to help programmers design clean and maintainable source code. See section Frame Hierarchy Programming Model for details.

The main features of asyncframes are:

• Simple syntax (compared with asyncio)

• Hierarchical composition of coroutines

• Creation of coroutine classes (a class whose lifetime is bound to the execution of a coroutine)

Introduction

Frame Hierarchy Programming Model

In the Frame Hierarchy Programming Model (FHM) a program is represented as a dynamic tree of frames. A frame is a suspendable function (a coroutine) with an object oriented context that only exists until the function runs out of scope. Frames can be used to represent both temporal processes (using the coroutine) and physical or conceptual objects (using the object oriented context).

Each FHM program has exactly one root frame. The root frame can recursively spawn child frames. Each child frame runs in parallel (using cooperative multitasking) unless it’s awaiting another frame or an awaitable event.

Frames can be removed in three ways:

1. The frame’s remove() function is called (either by the frame itself or by another frame).

2. The frame’s coroutine finishes (i.e. goes out of scope).

3. A parent frame is removed.

Installation

asyncframes can be installed via pip:

pip install asyncframes

asyncframes requires an event loop to suspend execution without blocking the operating system. The default event loop is asyncframes.asyncio_eventloop.EventLoop. It doesn’t depend on any Python packages besides the builtin asyncio package. Some frameworks, like Qt, use their own event loops. When using such frameworks, the framework’s event loop should be reused for asyncframes by implementing the asyncframes.AbstractEventLoop interface.

Examples

Here is a minimal example of using asyncframes:

from asyncframes import Frame
from asyncframes.asyncio_eventloop import EventLoop

@Frame
async def main_frame():
    print("Hello World!")

loop = EventLoop()
loop.run(main_frame)

Here is an example of suspending a frame:

from asyncframes import Frame, sleep
from asyncframes.asyncio_eventloop import EventLoop

@Frame
async def main_frame():
    for i in range(5):
        await sleep(1)
        print(i + 1)

loop = EventLoop()
loop.run(main_frame)

Here is an example of running two frames in parallel:

from asyncframes import Frame, sleep
from asyncframes.asyncio_eventloop import EventLoop

@Frame
async def counter(c):
    for i in range(5):
        await sleep(1)
        print(c)

@Frame
async def main_frame():
    a = counter('a') # Start counter 'a'
    await sleep(0.5) # Wait 0.5 seconds
    b = counter('b') # Start counter 'b'
    await (a & b) # Wait until both counters finish

loop = EventLoop()
loop.run(main_frame)

Changelog

1.1.0 (2018-09-18)

• Threadsafe events - Wake up event sources across threads using invoke().

• Free event - Frames emit the self.free event just before they are removed.

• Hierarchy changes - any_ and all_ do not take over parenthood of their awaitables.

1.0.0 (2018-09-05)

• Initial release