example memory channel context usage

withmem.txt

# 1 (ain't working, weird usage anyway)
>>> async def main():
...     incoming = open_memory_channel(15)
...     async with incoming:
...         await incoming[0].send(b'aaaa')
... 
>>> run(main)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/decentral1se/work/datpy/hypercore-protocol/.venv/lib/python3.8/site-packages/trio/_core/_run.py", line 1804, in run
    raise runner.main_task_outcome.error
  File "<stdin>", line 3, in main
AttributeError: __aexit__

# 2 (ain't working, more reasonable)
 >>> async def main():
...     async with open_memory_channel(15) as left, right:
...         await left.send(b'aaa')
... 
>>> run(main)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/decentral1se/work/datpy/hypercore-protocol/.venv/lib/python3.8/site-packages/trio/_core/_run.py", line 1804, in run
    raise runner.main_task_outcome.error
  File "<stdin>", line 2, in main
AttributeError: __aexit__

# 3 (works)
>>> from trio import *
>>> async def main():
...     left, right = open_memory_channel(15)
...     async with left, right:
...         await left.send(b'aaa')
... 
>>> run(main)

Outcome of the working usage is that if I want to use two channels, incoming and outgoing, I need to do:

    in_send, out_recv = open_memory_channel(0)
    out_send, out_recv = open_memory_channel(0)

    async with in_send, out_recv, out_send, out_recv:
        pass  # do stuff with the channels

Right? That feels a bit cumbersome at the moment but can work!

I would like to see that option 2 could work so that I can write objects that have the following interface:

class P:
    incoming: Tuple[MemorySendChannel, MemoryReceiveChannel]
    outgoing: Tuple[MemorySendChannel, MemoryReceiveChannel]

But instead, I need to (following the logic of breaking up the tuple to use in the context manager):

class P:
    in_send: MemorySendChannel
    in_recv: MemoryReceiveChannel

    out_send: MemorySendChannel
    out_recv: MemoryReceiveChannel

Or? This is only for the case where I want to instantiate the channel context outside of the P object. I'm doing this because I also instantiate my stream context externally of the object (so I can do P(stream=stream)) and so want to also follow this logic of composition with the channels.