AnyIO

#Introduction

AnyIO is an asynchronous networking and concurrency library that works on top of either asyncio or Trio. It implements Trio-like structured concurrency (SC) on top of asyncio and works in harmony with the native SC of Trio itself.

uv init anyio-basic
cd anyio-basic
uv add anyio

#Basic Usage

Let’s create a simple example.

Make a file called task.py and add this code:

import anyio

async def do_task():
    print("Start ... ", end="")
    await anyio.sleep(2)
    print("end!")


async def main():
    await do_task()

if __name__ == "__main__":
    anyio.run(main)

When working with async code you normally use async and await keywords.

The main rules are that:

• You can only use await inside async functions.
• To call an async function, you need to use await in front of it.

In this case, we can use await inside of main() because it is an async function.

#Call Async Functions

The function do_task() also needs to be declared with async def for us to be able to await for its result when calling it.

do_task() could be talking to a database, calling an API, or something else that needs to wait for something.

For this example, we simulate that by making do_task() wait there for 2 seconds:

async def do_task():
    print("Start ... ", end="")
    await anyio.sleep(2)
    print("end!")

#Run the main function

As main() is an async function, we can’t call it directly because we can’t await it.

Instead, we call it with anyio.run():

if __name__ == "__main__":
    anyio.run(main)