Improve examples and README (#102)

temeddix · hosaka · web-flow · commit e65c3421d204 · 2023-11-17T17:31:16.000+09:00
* Update and organize examples

* Remove an unused class variable

* Use Python's type hint

* Make executor example actually work

* Make the linter happy with tests

* Improve code readability

* Fix a wrong comment

* Simplify code

* Simplify code

* Fix variable names

* Fix the warning from session creation

* Simplify code

* Organize code

* Restore some variables for compatibility

* Improve README

* Improve guides

* Fix a title

* Improve details

* Make the basic example copy paste complete, tidy up the intro

* Add an example using QML

* Revert accidentally removed hunk

---------

Co-authored-by: Alex March &lt;alexmarch@fastmail.com&gt;
diff --git a/README.md b/README.md
@@ -9,19 +9,68 @@
 
 ## Introduction
 
-`qasync` allows coroutines to be used in PyQt/PySide applications by providing an implementation of the `PEP 3156` event-loop.
+`qasync` allows coroutines to be used in PyQt/PySide applications by providing an implementation of the `PEP 3156` event loop.
 
-`qasync` is a fork of [asyncqt](https://github.com/gmarull/asyncqt), which is a fork of [quamash](https://github.com/harvimt/quamash). May it live longer than its predecessors.
+With `qasync`, you can use `asyncio` functionalities directly inside Qt app's event loop, in the main thread. Using async functions for Python tasks can be much easier and cleaner than using `threading.Thread` or `QThread`.
 
-#### The future of `qasync`
+If you need some CPU-intensive tasks to be executed in parallel, `qasync` also got that covered, providing `QEventLoop.run_in_executor` which is functionally identical to that of `asyncio`.
 
-`qasync` was created because `asyncqt` and `quamash` are no longer maintained.
+### Basic Example
+
+```python
+import sys
+import asyncio
+
+from qasync import QEventLoop, QApplication
+from PySide6.QtWidgets import QWidget, QVBoxLayout
+
+class MainWindow(QWidget):
+    def __init__(self):
+        super().__init__()
+
+        self.setLayout(QVBoxLayout())
+        self.lbl_status = QLabel("Idle", self)
+        self.layout().addWidget(self.lbl_status)
+
+    @asyncClose
+    async def closeEvent(self, event):
+        pass
+
+    @asyncSlot()
+    async def onMyEvent(self):
+        pass
+
+
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+
+    event_loop = QEventLoop(app)
+    asyncio.set_event_loop(event_loop)
+
+    app_close_event = asyncio.Event()
+    app.aboutToQuit.connect(app_close_event.set)
+
+    main_window = MainWindow()
+    main_window.show()
+
+    with event_loop:
+        event_loop.run_until_complete(app_close_event.wait())
+```
+
+More detailed examples can be found [here](https://github.com/CabbageDevelopment/qasync/tree/master/examples).
+
+### The Future of `qasync`
+
+`qasync` is a fork of [asyncqt](https://github.com/gmarull/asyncqt), which is a fork of [quamash](https://github.com/harvimt/quamash). `qasync` was created because those are no longer maintained. May it live longer than its predecessors.
 
 **`qasync` will continue to be maintained, and will still be accepting pull requests.**
 
 ## Requirements
 
-`qasync` requires Python >= 3.8, and PyQt5/PyQt6 or PySide2/PySide6. The library is tested on Ubuntu, Windows and MacOS.
+- Python >= 3.8
+- PyQt5/PyQt6 or PySide2/PySide6
+
+`qasync` is tested on Ubuntu, Windows and MacOS.
 
 If you need Python 3.6 or 3.7 support, use the [v0.25.0](https://github.com/CabbageDevelopment/qasync/releases/tag/v0.25.0) tag/release.
 
diff --git a/examples/aiohttp_fetch.py b/examples/aiohttp_fetch.py
@@ -1,98 +1,82 @@
 import asyncio
-import functools
 import sys
 
 import aiohttp
 
-# from PyQt5.QtWidgets import (
-from PySide2.QtWidgets import (
-    QWidget,
+# from PyQt6.QtWidgets import (
+from PySide6.QtWidgets import (
+    QApplication,
     QLabel,
     QLineEdit,
-    QTextEdit,
     QPushButton,
+    QTextEdit,
     QVBoxLayout,
+    QWidget,
 )
-
-import qasync
-from qasync import asyncSlot, asyncClose, QApplication
+from qasync import QEventLoop, asyncClose, asyncSlot
 
 
 class MainWindow(QWidget):
     """Main window."""
 
-    _DEF_URL = "https://jsonplaceholder.typicode.com/todos/1"
-    """str: Default URL."""
-
-    _SESSION_TIMEOUT = 1.0
-    """float: Session timeout."""
+    _DEF_URL: str = "https://jsonplaceholder.typicode.com/todos/1"
+    """Default URL."""
 
     def __init__(self):
         super().__init__()
 
         self.setLayout(QVBoxLayout())
 
-        self.lblStatus = QLabel("Idle", self)
-        self.layout().addWidget(self.lblStatus)
+        self.lbl_status = QLabel("Idle", self)
+        self.layout().addWidget(self.lbl_status)
 
-        self.editUrl = QLineEdit(self._DEF_URL, self)
-        self.layout().addWidget(self.editUrl)
+        self.edit_url = QLineEdit(self._DEF_URL, self)
+        self.layout().addWidget(self.edit_url)
 
-        self.editResponse = QTextEdit("", self)
-        self.layout().addWidget(self.editResponse)
+        self.edit_response = QTextEdit("", self)
+        self.layout().addWidget(self.edit_response)
 
-        self.btnFetch = QPushButton("Fetch", self)
-        self.btnFetch.clicked.connect(self.on_btnFetch_clicked)
-        self.layout().addWidget(self.btnFetch)
+        self.btn_fetch = QPushButton("Fetch", self)
+        self.btn_fetch.clicked.connect(self.on_btn_fetch_clicked)
+        self.layout().addWidget(self.btn_fetch)
 
-        self.session = aiohttp.ClientSession(
-            loop=asyncio.get_event_loop(),
-            timeout=aiohttp.ClientTimeout(total=self._SESSION_TIMEOUT),
-        )
+        self.session: aiohttp.ClientSession
 
     @asyncClose
-    async def closeEvent(self, event):
+    async def closeEvent(self, event):  # noqa:N802
         await self.session.close()
 
+    async def boot(self):
+        self.session = aiohttp.ClientSession()
+
     @asyncSlot()
-    async def on_btnFetch_clicked(self):
-        self.btnFetch.setEnabled(False)
-        self.lblStatus.setText("Fetching...")
+    async def on_btn_fetch_clicked(self):
+        self.btn_fetch.setEnabled(False)
+        self.lbl_status.setText("Fetching...")
 
         try:
-            async with self.session.get(self.editUrl.text()) as r:
-                self.editResponse.setText(await r.text())
+            async with self.session.get(self.edit_url.text()) as r:
+                self.edit_response.setText(await r.text())
         except Exception as exc:
-            self.lblStatus.setText("Error: {}".format(exc))
+            self.lbl_status.setText("Error: {}".format(exc))
         else:
-            self.lblStatus.setText("Finished!")
+            self.lbl_status.setText("Finished!")
         finally:
-            self.btnFetch.setEnabled(True)
-
-
-async def main():
-    def close_future(future, loop):
-        loop.call_later(10, future.cancel)
-        future.cancel()
+            self.btn_fetch.setEnabled(True)
 
-    loop = asyncio.get_event_loop()
-    future = asyncio.Future()
 
-    app = QApplication.instance()
-    if hasattr(app, "aboutToQuit"):
-        getattr(app, "aboutToQuit").connect(
-            functools.partial(close_future, future, loop)
-        )
-
-    mainWindow = MainWindow()
-    mainWindow.show()
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
 
-    await future
-    return True
+    event_loop = QEventLoop(app)
+    asyncio.set_event_loop(event_loop)
 
+    app_close_event = asyncio.Event()
+    app.aboutToQuit.connect(app_close_event.set)
+    
+    main_window = MainWindow()
+    main_window.show()
 
-if __name__ == "__main__":
-    try:
-        qasync.run(main())
-    except asyncio.exceptions.CancelledError:
-        sys.exit(0)
+    event_loop.create_task(main_window.boot())
+    event_loop.run_until_complete(app_close_event.wait())
+    event_loop.close()
diff --git a/examples/executor_example.py b/examples/executor_example.py
@@ -1,11 +1,10 @@
 import functools
-import sys
 import asyncio
 import time
-import qasync
+import sys
 
-# from PyQt5.QtWidgets import (
-from PySide2.QtWidgets import QApplication, QProgressBar
+# from PyQt6.QtWidgets import
+from PySide6.QtWidgets import QApplication, QProgressBar
 from qasync import QEventLoop, QThreadExecutor
 
 
@@ -32,4 +31,11 @@ def last_50(progress, loop):
         time.sleep(0.1)
 
 
-qasync.run(master())
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+
+    event_loop = QEventLoop(app)
+    asyncio.set_event_loop(event_loop)
+
+    event_loop.run_until_complete(master())
+    event_loop.close()
diff --git a/examples/qml_httpx/app.py b/examples/qml_httpx/app.py
@@ -0,0 +1,41 @@
+import sys
+import asyncio
+from pathlib import Path
+
+from qasync import QEventLoop, QApplication
+from PySide6.QtCore import QUrl
+from PySide6.QtQml import QQmlApplicationEngine, qmlRegisterType
+
+from service import ExampleService
+
+QML_PATH = Path(__file__).parent.absolute().joinpath("qml")
+
+
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+
+    engine = QQmlApplicationEngine()
+    engine.addImportPath(QML_PATH)
+
+    app.aboutToQuit.connect(engine.deleteLater)
+    engine.quit.connect(app.quit)
+
+    # register our service, making it usable directly in QML
+    qmlRegisterType(ExampleService, "qasync", 1, 0, ExampleService.__name__)
+
+    # alternatively, instantiate the service and inject it into the QML engine
+    # service = ExampleService()
+    # engine.rootContext().setContextProperty("service", service)
+
+    event_loop = QEventLoop(app)
+    asyncio.set_event_loop(event_loop)
+
+    app_close_event = asyncio.Event()
+    app.aboutToQuit.connect(app_close_event.set)
+    engine.quit.connect(app_close_event.set)
+
+    qml_entry = QUrl.fromLocalFile(str(QML_PATH.joinpath("Main.qml")))
+    engine.load(qml_entry)
+
+    with event_loop:
+        event_loop.run_until_complete(app_close_event.wait())
diff --git a/examples/qml_httpx/qml/Main.qml b/examples/qml_httpx/qml/Main.qml
@@ -0,0 +1,18 @@
+import QtQuick 2.15
+import QtQuick.Controls 2.15
+import QtQuick.Layouts 1.15
+import QtQuick.Window 2.15
+
+ApplicationWindow {
+    id: root
+    title: "qasync"
+    visible: true
+    width: 420
+    height: 240
+
+    Loader {
+        id: mainLoader
+        anchors.fill: parent
+        source: "Page.qml"
+    }
+}
diff --git a/examples/qml_httpx/qml/Page.qml b/examples/qml_httpx/qml/Page.qml
@@ -0,0 +1,65 @@
+import QtQuick 2.15
+import QtQuick.Controls 2.15
+import QtQuick.Controls.Material 2.15
+import QtQuick.Layouts 1.15
+
+Item {
+    ExampleService {
+        id: service
+
+        // handle value changes inside the service object
+        onValueChanged: {
+            // use value
+        }
+    }
+
+    Connections {
+        target: service
+
+        // handle value changes with an external Connection
+        function onValueChanged(value) {
+            // use value
+        }
+    }
+
+    ColumnLayout {
+        anchors {
+            fill: parent
+            margins: 10
+        }
+
+        RowLayout {
+            Layout.fillWidth: true
+
+            Button {
+                id: button
+                Layout.preferredWidth: 100
+                enabled: !service.isLoading
+
+                text: {
+                    return service.isLoading ? qsTr("Loading...") : qsTr("Fetch")
+                }
+                onClicked: function() {
+                    service.fetch(url.text)
+                }
+            }
+
+            TextField {
+                id: url
+                Layout.fillWidth: true
+                enabled: !service.isLoading
+                text: qsTr("https://jsonplaceholder.typicode.com/todos/1")
+            }
+        }
+
+        TextEdit {
+            id: text
+            Layout.fillHeight: true
+            Layout.fillWidth: true
+
+            // react to value changes from other widgets
+            text: service.value
+        }
+    }
+
+}
diff --git a/examples/qml_httpx/service.py b/examples/qml_httpx/service.py
diff --git a/tests/test_qeventloop.py b/tests/test_qeventloop.py
