[Async-sig] new library: sniffio – Sniff out which async library your code is running under

[Nathaniel Smith]

Hi all,

A number of people are working on packages that support multiple async
backends (e.g., asyncio + trio, or trio + curio, or trio + twisted,
...). So then the question arises... how can I figure out which async
library my user is actually using?

Answer: install sniffio, and then call
sniffio.current_async_library(), and it tells you.

Well, right now it only works for trio and asyncio, but if you
maintain an async library and you want to make it easier for packages
to detect you, then it's easy to add support – see the manual. We
considered various clever things, but ultimately decided that the best
approach was to use a ContextVar and make it the coroutine runner's
responsibility to advertise which async flavor it uses. In particular,
this approach works even for hybrid programs that are using multiple
coroutine runners in the same loop, like a Twisted program with
asyncio-flavored and twisted-flavored coroutines in the same thread,
or a Trio program using trio-asyncio to run both asyncio-flavored and
trio-flavored coroutines in the same thread.

Github: https://github.com/python-trio/sniffio
Manual: https://sniffio.readthedocs.io/
PyPI: https://pypi.org/p/sniffio

-n

-- 
Nathaniel J. Smith -- https://vorpus.org