qasync

import asyncio import sys # Choose your Qt binding: PyQt5, PyQt6, PySide2, PySide6 # For this example, we'll use PyQt5 from PyQt5.QtWidgets import QApplication, QLabel, QVBoxLayout, QWidget, QPushButton from qasync import QEventLoopPolicy, asyncSlot async def long_running_task(duration_seconds: int = 2): """A mock asynchronous task.""" print(f"[Task] Starting long-running task for {duration_seconds} seconds...") await asyncio.sleep(duration_seconds) print("[Task] Long-running task finished!") return "Task Completed!" class MainWindow(QWidget): def __init__(self): super().__init__() self.setWindowTitle("qasync Quickstart Demo") self.setGeometry(100, 100, 400, 200) self.layout = QVBoxLayout() self.label = QLabel("Click the button to start an async task.") self.button = QPushButton("Run Async Task") # Connect a Qt signal to an asynchronous slot using @asyncSlot self.button.clicked.connect(self.run_task) self.layout.addWidget(self.label) self.layout.addWidget(self.button) self.setLayout(self.layout) @asyncSlot() async def run_task(self): """This slot runs an async task without blocking the GUI.""" self.label.setText("Task started, please wait...") self.button.setEnabled(False) # Disable button while task is running result = await long_running_task(3) # Await the async task self.label.setText(f"Result: {result}") self.button.setEnabled(True) # Re-enable button if __name__ == "__main__": # IMPORTANT: Set the asyncio event loop policy *before* creating QApplication asyncio.set_event_loop_policy(QEventLoopPolicy()) app = QApplication(sys.argv) window = MainWindow() window.show() # Run the Qt application sys.exit(app.exec_())