awaitlet 0.0.0

invoke asyncio awaitables from non-async functions

Call Python asyncio awaitables from functions that are not declared as async.

Synopsis

Consider the following asyncio program that sends and receives messages from an echo server:

import asyncio

async def sendrecv(msg):
    reader, writer = await asyncio.open_connection("tcpbin.com", 4242)
    writer.write(f"message number {msg}\n".encode("ascii"))
    await writer.drain()
    data = (await reader.read(1024)).decode("utf-8")
    return data


async def main():
    messages = await asyncio.gather(
        *[
            sendrecv(msg) for msg in
            ["one", "two", "three", "four", "five"]
        ]
    )
    for msg in messages:
        print(f"Got back echo response: {msg}")

asyncio.run(main())

What if sendrecv above wanted to be a function available in existing code that didn’t use async? With awaitlet we can remove the async keyword and still have a way of invoking async awaitables inside of it:

import asyncio
from awaitlet import async_def
from awaitlet import awaitlet

def sendrecv_implementation(msg):
    reader, writer = awaitlet(asyncio.open_connection("tcpbin.com", 4242))
    writer.write(f"message number {msg}\n".encode("ascii"))
    awaitlet(writer.drain())
    data = (awaitlet(reader.read(1024))).decode("utf-8")
    return data

async def sendrecv(msg):
    return await async_def(sendrecv_implementation, msg)

async def main():
    messages = await asyncio.gather(
        *[
            sendrecv(msg) for msg in
            ["one", "two", "three", "four", "five"]
        ]
    )
    for msg in messages:
        print(f"Got back echo response: {msg}")

asyncio.run(main())