You're writing a library. You've decided to be ambitious, and support multiple async I/O packages, like Trio, and asyncio, and ... You've written a bunch of clever code to handle all the differences. But... how do you know which piece of clever code to run?

This is a tiny package whose only purpose is to let you detect which async library your code is running under.

• Documentation: https://sniffio.readthedocs.io
• Bug tracker and source code: https://github.com/python-trio/sniffio
• License: MIT or Apache License 2.0, your choice
• Contributor guide: https://trio.readthedocs.io/en/latest/contributing.html
• Code of conduct: Contributors are requested to follow our code of conduct in all project spaces.

This library is maintained by the Trio project, as a service to the async Python community as a whole.

from sniffio import current_async_library
import trio
import asyncio

async def print_library():
    library = current_async_library()
    print("This is:", library)

# Prints "This is trio"
trio.run(print_library)

# Prints "This is asyncio"
asyncio.run(print_library())

For more details, including how to add support to new async libraries, please peruse our fine manual.