https://github.com/python-trio/async_generator

Making it easy to write async iterators in Python 3.5
https://github.com/python-trio/async_generator

backports generators polyfill python python-3-5

Last synced: 1 day ago
JSON representation

Making it easy to write async iterators in Python 3.5

• Host: GitHub
• URL: https://github.com/python-trio/async_generator
• Owner: python-trio
• License: other
• Created: 2016-05-31T18:14:56.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2020-08-24T19:49:32.000Z (about 4 years ago)
• Last Synced: 2024-04-14T09:04:51.013Z (6 months ago)
• Topics: backports, generators, polyfill, python, python-3-5
• Language: Python
• Homepage:
• Size: 150 KB
• Stars: 94
• Watchers: 11
• Forks: 24
• Open Issues: 9
• Metadata Files:
  • Readme: README.rst
  • Contributing: CONTRIBUTING.md
  • License: LICENSE
  • Code of conduct: CODE_OF_CONDUCT.md

Awesome Lists containing this project

README

        
.. image:: https://img.shields.io/badge/chat-join%20now-blue.svg

   :target: https://gitter.im/python-trio/general

   :alt: Join chatroom

.. image:: https://img.shields.io/badge/docs-read%20now-blue.svg

   :target: https://async-generator.readthedocs.io/en/latest/?badge=latest

   :alt: Documentation Status

.. image:: https://travis-ci.org/python-trio/async_generator.svg?branch=master

   :target: https://travis-ci.org/python-trio/async_generator

   :alt: Automated test status

.. image:: https://ci.appveyor.com/api/projects/status/af4eyed8o8tc3t0r/branch/master?svg=true

   :target: https://ci.appveyor.com/project/python-trio/trio/history

   :alt: Automated test status (Windows)

.. image:: https://codecov.io/gh/python-trio/async_generator/branch/master/graph/badge.svg

   :target: https://codecov.io/gh/python-trio/async_generator

   :alt: Test coverage

The async_generator library

===========================

Python 3.6 added `async generators

`__. (What's an async

generator? `Check out my 5-minute lightning talk demo from PyCon 2016

`__.) Python 3.7 adds some more

tools to make them usable, like ``contextlib.asynccontextmanager``.

This library gives you all that back to Python 3.5.

For example, this code only works in Python 3.6+:

.. code-block:: python3

   async def load_json_lines(stream_reader):

       async for line in stream_reader:

           yield json.loads(line)

But this code does the same thing, and works on Python 3.5+:

.. code-block:: python3

   from async_generator import async_generator, yield_

   @async_generator

   async def load_json_lines(stream_reader):

       async for line in stream_reader:

           await yield_(json.loads(line))

Or in Python 3.7, you can write:

.. code-block:: python3

   from contextlib import asynccontextmanager

   @asynccontextmanager

   async def background_server():

       async with trio.open_nursery() as nursery:

           value = await nursery.start(my_server)

           try:

               yield value

           finally:

               # Kill the server when the scope exits

               nursery.cancel_scope.cancel()

This is the same, but back to 3.5:

.. code-block:: python3

   from async_generator import async_generator, yield_, asynccontextmanager

   @asynccontextmanager

   @async_generator

   async def background_server():

       async with trio.open_nursery() as nursery:

           value = await nursery.start(my_server)

           try:

               await yield_(value)

           finally:

               # Kill the server when the scope exits

               nursery.cancel_scope.cancel()

(And if you're on 3.6, you can use ``@asynccontextmanager`` with

native generators.)

Let's do this

=============

* Install: ``python3 -m pip install -U async_generator`` (or on Windows,

  maybe ``py -3 -m pip install -U async_generator``

* Manual: https://async-generator.readthedocs.io/

* Bug tracker and source code: https://github.com/python-trio/async_generator

* Real-time chat: https://gitter.im/python-trio/general

* License: MIT or Apache 2, 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.

How come some of those links talk about "trio"?

===============================================

`Trio `__ is a new async concurrency

library for Python that's obsessed with usability and correctness – we

want to make it *easy* to get things *right*. The ``async_generator``

library is maintained by the Trio project as part of that mission, and

because Trio uses ``async_generator`` internally.

You can use ``async_generator`` with any async library. It works great

with ``asyncio``, or Twisted, or whatever you like. (But we think Trio

is pretty sweet.)