generators

test.py

import types


class MyError(Exception): pass


@types.coroutine
def _async_yield(v):
    return (yield v)


async def test():
    try:
        await _async_yield(1)
    except MyError:
        await _async_yield(2)
    return
    yield


def thin_anext(gen):
    return gen.__anext__()


async def thick_anext(gen):
    return await gen.__anext__()


def run(anext):
    print('\n\n+++ run', anext)

    gen = test()

    aw = anext(gen).__await__()
    print('1. send', aw.send(None))
    aw.close()

    aw = anext(gen).__await__()
    try:
        val = aw.throw(MyError, MyError(), None)
        print('2. throw: got value', val)
    except MyError as e:
        print('2. throw: got error', type(e), e)


run(thin_anext)
run(thick_anext)

+++ run <function thin_anext at 0x7fd1cd682840>
1. send 1
2. throw: got value 2


+++ run <function thick_anext at 0x7fd1cd6828e0>
1. send 1
2. throw: got error <class '__main__.MyError'>