mikaelho
commented
1 year ago Having asyncio support "natively" would be awesome -- but it does seem like a lot of work. Sprinkling async and await all over the place does make any code look unwieldy, and maintaining the sync alternatives seems like almost doubling the maintenance effort.
Anyone wanting to call into async functions from flet code could take advantage of the minimal unsync package, where a simple usage example would be:
import asyncio
import flet
from flet import ElevatedButton
from flet import Page
from unsync import unsync
def clicked(event):
something_async()
@unsync
async def something_async():
print("Starting an async operation")
await asyncio.sleep(1)
print("Finished")
def main(page: Page):
page.add(ElevatedButton("Click me to do something async", on_click=clicked))
page.update()
flet.app(target=main)unsync maintains a singleton loop for its use, so the overhead is reasonable for most use cases.
TutorExilius
FeodorFitsner
roniemartinez
JartanFTW
The other half of the time it works as expected.
890r121289rh
Discussed in https://github.com/flet-dev/flet/discussions/72
Problem
It is currently impossible to call
asyncmethod from Flet event handlers. They are synchronous functions run in separate threads. This limitation requires to use bulky constructs like:where
get_weather(search_value)is async function.Solution
As in other languages like C# a "proper" async must be implemented from ground up - it's impossible/ineffective to partially support calling
asyncmethods from sync ones. The entire program must be running in an event loop (in Python terms).Flet Python client must be re-implemented to use
asynciolibrary.Sample code
Flet client will be providing both sync and async methods, for example async version of "Hello, world" might look like:
All async methods will have
_asyncsuffix.WebSockets client will be implemented with websockets library based on
asyncio.Resources:
Flet API
Sync is going to be default style of writing Flet apps. Flet API that needs to be available in both sync and async variants:
Connectionclass - have a baseConnectionclass and two implementations:SyncConnectionandAsyncConnection:def connect()async def connect_async()def send_command(self, session_id: str, command: Command)async def send_command_async(self, session_id: str, command: Command)def send_commands(self, session_id: str, commands: List[Command])async def send_commands_async(self, session_id: str, commands: List[Command])def close(self)on_event- could be eitherCallableorCoroutineon_session_created- could be eitherCallableorCoroutineReconnectingWebSocketmust be created insideSyncConnection.send_commandsonly in all cases?Pageclass: