python3-with-stmt

参考https://docs.python.org/3/reference/compound_stmts.html#async-with

改造了一个异步上下文管理器

python -version : 3.6.6

import asyncio
import aiomysql
import sys


async def test_example(loop):
    pool = await aiomysql.create_pool(host='127.0.0.1', port=3308,
                                      user='finger', password='fypingfyping',
                                      db='userlogin_test', loop=loop)
    mgr =  await pool.acquire()
    aexit = aiomysql.connection.Connection.__aexit__
    aenter = await aiomysql.connection.Connection.__aenter__(mgr)
    conn =  aenter
    try:
        mg = await conn.cursor()
        aexit_ = aiomysql.cursors.Cursor.__aexit__
        aenter_ = await aiomysql.cursors.Cursor.__aenter__(mg)
        cur =  aenter_
        try:
            await cur.execute("select 48")
            print(cur.description)
            (r,) = await cur.fetchone()
            assert  r==48
        except:
            if not await aexit_(mg,*sys.exc_info()):
                raise
        else:
            await aexit_(mg,None,None,None)
    except :
        if not await aexit(mgr,*sys.exc_info()):
            raise 
    else:
        await aexit(mgr,None,None,None)
    pool.close()
    await pool.wait_closed()


async def test_example_0(loop):
    pool = await aiomysql.create_pool(host='127.0.0.1', port=3306,
                                      user='root', password='',
                                      db='mysql', loop=loop)
    async with pool.acquire() as conn:
        async with conn.cursor() as cur:
            await cur.execute("SELECT 42;")
            print(cur.description)
            (r,) = await cur.fetchone()
            assert r == 42
    pool.close()
    await pool.wait_closed()


loop = asyncio.get_event_loop()
loop.run_until_complete(test_example(loop))

源代码是 aiomysql的demos，这里的test_example_0