Asynchronous context manager
In Python 3.7, you'll be able to write:
from contextlib import asynccontextmanager
@asynccontextmanager
async def smtp_connection():
client = SMTPAsync()
...
try:
await client.connect(smtp_url, smtp_port)
await client.starttls()
await client.login(smtp_username, smtp_password)
yield client
finally:
await client.quit()
Until 3.7 comes out, you can use the async_generator
package for this. On 3.6, you can write:
# This import changed, everything else is the same
from async_generator import asynccontextmanager
@asynccontextmanager
async def smtp_connection():
client = SMTPAsync()
...
try:
await client.connect(smtp_url, smtp_port)
await client.starttls()
await client.login(smtp_username, smtp_password)
yield client
finally:
await client.quit()
And if you want to work all the way back to 3.5, you can write:
# This import changed again:
from async_generator import asynccontextmanager, async_generator, yield_
@asynccontextmanager
@async_generator # <-- added this
async def smtp_connection():
client = SMTPAsync()
...
try:
await client.connect(smtp_url, smtp_port)
await client.starttls()
await client.login(smtp_username, smtp_password)
await yield_(client) # <-- this line changed
finally:
await client.quit()
Thanks to @jonrsharpe was able to make an async context manager.
Here's what mine ended up looking like for anyone who want's some example code:
class SMTPConnection():
def __init__(self, url, port, username, password):
self.client = SMTPAsync()
self.url = url
self.port = port
self.username = username
self.password = password
async def __aenter__(self):
await self.client.connect(self.url, self.port)
await self.client.starttls()
await self.client.login(self.username, self.password)
return self.client
async def __aexit__(self, exc_type, exc, tb):
await self.client.quit()
usage:
async with SMTPConnection(url, port, username, password) as client:
await client.sendmail(...)
Feel free to point out if I've done anything stupid.
The asyncio_extras package has a nice solution for this:
import asyncio_extras
@asyncio_extras.async_contextmanager
async def smtp_connection():
client = SMTPAsync()
...
For Python < 3.6, you'd also need the async_generator package and replace yield client
with await yield_(client)
.