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Description:

asyncio utils 0.1.4

Asyncio utilities for python >= 3.6
A small package of utilities that mimics some builtin methods, but in an
asynchronous fashion.

Free software: MIT license

Features

Asyncio utilities

Install
To install:
pip install asyncio-utils

Usage
Almost everything is used with the await keyword before unless marked
otherwise. However most of the method inputs can be awaitable (but not
actually awaited yet) and they will still work, unless marked otherwise.
To run any of the examples:
import asyncio
loop = asyncio.get_event_loop()

aiter
Wraps/ensures an AsyncIterator.
If the input is Awaitable, then we will await the result, and check
if it returns and AsyncIterator.
If the input is an async generator that was not called, then we will
call it and yield it’s values.
Else if the input is an iterator we iterate it and yield the values.
Examples:
>>> async def main():
async for v in aiter2(range(1, 5)): # normal iterator
print(v)

>>> loop.run_until_complete(main())
1
2
3
4

>>> async def main():
async for v in aiter2(arange(1, 5)): # not awaited
print(v)

>>> loop.run_until_complete(main())
1
2
3
4

>>> async def main():
async for v in aiter2(await arange(1, 5)): # awaited works
print(v)

>>> loop.run_until_complete(main())
1
2
3
4

>>> async def agen():
yield 1
yield 2
yield 3
yield 4

>>> async def main():
async for v in aiter2(agen): # oops forgot to call it
print(v)

>>> loop.run_until_complete(main())
1
2
3
4

anext
Mimics the builtin next method. This method will not accept an
awaitable. The input must be an AsyncIterator or you will get a
TypeError.
Example:
>>> async def main():
myrange = await arange(1, 5)
for n in range(1, 5):
print(n, n == await anext(myrange))
try:
n = await anext(myrange)
print("This should not be shown")
except StopAsyncIteration:
print('Sorry no more values!')

>>> loop.run_until_complete(main())
1 True
2 True
3 True
4 True
Sorry no more values!
Example of using a default value if a StopAsyncIteration has occured:
>>> async def main():
myrange = await arange(1)
print(await anext(myrange))
print(await anext(myrange, 'Sorry no more values!'))
# or as kwarg
print(await anext(myrange, default='Still no more values!'))

>>> loop.run_until_complete(main())
1
Sorry no more values!
Still no more values!
Example failure because a non AsyncIterator passed in:
>>> async def main():
val = await anext(arange(1, 5))
print(val) # never get here

>>> loop.run_until_complete(main())
Traceback (most recent call last):
...
TypeError: Not an AsyncIterator: <coroutine object arange at 0x1068170f8>

amap
AsyncGenerator that mimics the builtin map method.

Note
You do not use await on AsyncGenerator’s

Example:
>>> async def main():
async for val in amap('${}'.format, arange(1, 5)):
print(val)

>>> loop.run_until_complete(main())
$1
$2
$3
$4
This also works if the function passed in is a coroutine:
>>> async def formatter(val):
return f'${val}'

>>> async def main():
async for val in amap(formatter, arange(1, 5)):
print(val)

>>> loop.run_until_complete(main())
$1
$2
$3
$4

afilter
An async generator that mimics the builtin filter method.
Example:
>>> async def main():
myfilter = await afilter(lambda x: x == 2, arange(1, 5))
print(await anext(myfilter, 'Oops no more twos'))
print(await anext(myfilter, 'Oops no more twos'))

>>> loop.run_until_complete(main())
2
Oops no more twos

arange
Mimics the builtin range method. Returning an AsyncIterator.
Example:
>>> async def main():
myrange = await arange(1, 5)
async for n in myrange:
print(n)

>>> loop.run_until_complete(main())
1
2
3
4

alist
Transform an AsyncIterator to a list. This would be equivalent to:
[v async for v in async_iterator]
However we ensure that the async_iterator is actually an AsyncIterator.
Example:
>>> async def main():
print(await alist(arange(1, 5)))
# or
print(await alist(await arange(1, 5)))

>>> loop.run_until_complete(main())
[1, 2, 3, 4]
[1, 2, 3, 4]

atuple
Transform an AsyncIterator to a tuple. This would be equivalent to:
tuple([v async for v in async_iterator])
However we ensure that the async_iterator is actually an AsyncIterator.
Example:
>>> async def main():
print(await atuple(arange(1, 5)))
# or
print(await atuple(await arange(1, 5)))

>>> loop.run_until_complete(main())
(1, 2, 3, 4)
(1, 2, 3, 4)

aset
Transform an AsyncIterator to a set. This would be equivalent to:
{v async for v in async_iterator}
However we ensure that the async_iterator is actually an AsyncIterator.
Example:
>>> async def main():
print(await aset(arange(1, 5)))
# or
print(await aset(await arange(1, 5)))

>>> loop.run_until_complete(main())
{1, 2, 3, 4}
{1, 2, 3, 4}

adict
Transform an AsyncIterator to a dict. This would be equivalent to:
{k: v async for (k, v) in async_iterator}
However we ensure that the async_iterator is actually an AsyncIterator.
Example:
>>> async def k_v_gen():
async for n in await arange(1, 5):
yield (n, n * 2)

>>> async def main():
print(await adict(k_v_gen()))

>>> loop.run_until_complete(main())
{1: 2, 2: 4, 3: 6, 4: 8}

transform_factory
This can be used to transform an AsyncIterator into any callable. This is
the base for alist, aset, atuple, and adict. While not tested,
in theory, you should be able to transform it into the output of any
callable that takes a standard iterator.
Example of how the alist method is declared in the code:
>>> import functools
>>> alist = functools.partial(transform_factory, _type=list)
>>> alist.__doc__ = """Async list documentation."""

>>> async def main():
print(await alist(arange(1, 5)))

>>> loop.run_until_complete(main())
[1, 2, 3, 4]

make_async
Make’s any callable awaitable. Can be used as a decorator.
Example:
>>> class AClass(object):

def __init__(self):
self.a = 'a'

>>> async_aclass = make(async_aclass)

# or as a decorator
>>> @make_async
def sync_a():
return 'a'

>>> async def main():
async_a = await async_aclass()
print(async_a.a == 'a')

print(await sync_a())