colorblind-async

Warning This is only a proof-of-concept.

Usage

1. import ColorblindAsync from colorblind_async
2. init by: ColorblindAsync.init()
3. include files/modules with awaits outside async context
4. run

Example

main.py

from colorblind_async import ColorblindAsync

ColorblindAsync.init()

import file # now when you include other modules, the colorblind_async will do it's job

# await my_coro() # you cannot do that here, colorblind_async binds to import statement and it won't work here

file.py

async def my_coro():
    return "foo"

def my_sync_fn():
    await my_coro() #  call `await` in sync function

await my_coro() # I can even call `await` outside any function

Install

pip3 install colorblind-async

Optional setup

Pass already defined event loop

from colorblind_async import ColorblindAsync

ColorblindAsync.init(loop=my_loop)

Debug

Prints altered code with awaits outside async context replaced with __colorblind_async__(coro) call.

DEBUG_COLORBLIND_ASYNC=True python script.py

Run Tests

make test

How does it work

After you import colorblind_async module, it'll enhance the include function to catch SyntaxError await outside function.... When it catches it, it parse AST of the included file and replace await keyword with call __colorblind_async__(coroutine). __colorblind_async__ is simple wrapper which executes passed coroutine in the (provided) event loop. Because you can call sync functions from async context and then call async context in a nested fashion, library nest-asyncio is used for reentrant async semantics.

Limitations

As per library nest-asyncio: only event loops from asyncio can be patched; Loops from other projects, such as uvloop or quamash, generally can't be patched.

Be aware of unexpected preemptions as they may occur outside of visible async keyword context and you may need to apply additional synchronization.

FAQ

Why?

Python async is more complicated than it needs to be. And I like the idea of Zig's colorblind Async/Await. Obviously there are cases when you do not care about event loop stuff and just what the code running without spending too much time on dealing with sync/async parts calling each other.

Is this dark magic?

Well, um, technically yes. Because it allows you to import syntactically incorrect program, so use it with caution. But don't worry, no kittens were harmed during the experiments.