如何将回调和期货与 asyncio 和 PyQt5 事件循环一起使用？

Question

这是我编写的一个小测试程序，试图了解如何将 PyQt 事件循环与 asyncio:

一起使用

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton
from PyQt5 import QtCore
import qasync
import asyncio

async def main():
    app = QApplication(sys.argv)
    asyncio.set_event_loop(qasync.QEventLoop(app))
    window = QMainWindow()
    window.setGeometry(100, 100, 200, 200)
    button = QPushButton(window)
    button.move(50, 50)
    button.resize(100, 100)
    button.setText('Run')
    future = None
    def run_action():
        future.set_result('run clicked')
    button.clicked.connect(run_action)
    window.setWindowTitle('Testing async event loop')
    window.show()
    await asyncio.sleep(1)
    i = 0
    while True:
        future = asyncio.get_event_loop().create_future()
        result = await future
        i += 1
        if i == 4:
            break
    print("Done")

asyncio.run(main())

这给了我以下错误：

Traceback (most recent call last):
  File "/home/hakon/test/python/async/./t.py", line 36, in <module>
    asyncio.run(main())
  File "/home/hakon/.pyenv/versions/3.9.4/lib/python3.9/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/home/hakon/.pyenv/versions/3.9.4/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
    return future.result()
  File "/home/hakon/test/python/async/./t.py", line 25, in main
    await asyncio.sleep(1)
  File "/home/hakon/.pyenv/versions/3.9.4/lib/python3.9/asyncio/tasks.py", line 654, in sleep
    return await future
RuntimeError: Task <Task pending name='Task-1' coro=<main() running at /home/hakon/test/python/async/./t.py:25> cb=[_run_until_complete_cb() at /home/hakon/.pyenv/versions/3.9.4/lib/python3.9/asyncio/base_events.py:184]> got Future <Future pending> attached to a different loop

知道我在这里遗漏了什么吗？我该如何改进此代码？

Answer 1

问题是您是运行一个事件循环，然后您刚刚创建了 Qt 事件循环。有 2 种可能的解决方案：

在执行协程main之前设置eventloop:

import asyncio
import sys

from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton
import qasync


async def main():
    window = QMainWindow()
    window.setGeometry(100, 100, 200, 200)
    button = QPushButton(window)
    button.move(50, 50)
    button.resize(100, 100)
    button.setText("Run")
    future = None

    def run_action():
        if future is not None:
            future.set_result("run clicked")

    button.clicked.connect(run_action)
    window.setWindowTitle("Testing async event loop")
    window.show()
    await asyncio.sleep(1)
    i = 0
    while True:
        future = asyncio.get_event_loop().create_future()
        result = await future
        i += 1
        if i == 4:
            break
    print("Done")


app = QApplication(sys.argv)
loop = qasync.QEventLoop(app)
asyncio.set_event_loop(loop)
with loop:
    loop.run_until_complete(main())

或使用qasync.run():

import asyncio
import sys

from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton
import qasync


async def main():
    window = QMainWindow()
    window.setGeometry(100, 100, 200, 200)
    button = QPushButton(window)
    button.move(50, 50)
    button.resize(100, 100)
    button.setText("Run")
    future = None

    def run_action():
        if future is not None:
            future.set_result("run clicked")

    button.clicked.connect(run_action)
    window.setWindowTitle("Testing async event loop")
    window.show()
    await asyncio.sleep(1)
    i = 0
    while True:
        future = asyncio.get_event_loop().create_future()
        result = await future
        i += 1
        if i == 4:
            break
    print("Done")


qasync.run(main())

如何将回调和期货与 asyncio 和 PyQt5 事件循环一起使用？

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