PySide2 Signal with named parameter

问题:

I am trying to replicate below example using PySide2.

https://evileg.com/en/post/242/

But as PySide2 doesn't support emitting a Signal with named parameter to QML, i have no clue about how to do this using PySide2 ?

Here is my code

main.py

from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine
from PySide2.QtCore import QObject, Signal, Slot, Property


class Calculator(QObject):
    def __init__(self):
        QObject.__init__(self)

    sumResult = Signal(int)
    subResult = Signal(int)

    @Slot(int, int)
    def sum(self, arg1, arg2):
        self.sumResult.emit(arg1 + arg2)

    @Slot(int, int)
    def sub(self, arg1, arg2):
        self.subResult.emit(arg1 - arg2)


if __name__ == "__main__":
    import sys

    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    calculator = Calculator()
    engine.rootContext().setContextProperty("calculator", calculator)
    engine.load("/code/QML/calc.qml")

    engine.quit.connect(app.quit)
    sys.exit(app.exec_())

回答1:

You can not replicate it like this, if you want to implement the project you can make the slot return the value:

main.py

from PySide2 import QtCore, QtGui, QtQml


class Calculator(QtCore.QObject):
    # Slot for summing two numbers
    @QtCore.Slot(int, int, result=int)
    def sum(self, arg1, arg2):
        return arg1 + arg2

    # Slot for subtraction of two numbers
    @QtCore.Slot(int, int, result=int)
    def sub(self, arg1, arg2):
        return arg1 - arg2


if __name__ == "__main__":
    import os
    import sys

    # Create an instance of the application
    app = QtGui.QGuiApplication(sys.argv)
    # Create QML engine
    engine = QtQml.QQmlApplicationEngine()
    # Create a calculator object
    calculator = Calculator()
    # And register it in the context of QML
    engine.rootContext().setContextProperty("calculator", calculator)
    # Load the qml file into the engine
    file = os.path.join(os.path.dirname(os.path.realpath(__file__)), "main.qml")
    engine.load(file)

    engine.quit.connect(app.quit)
    sys.exit(app.exec_())

main.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.2

ApplicationWindow {
    visible: true
    width: 640
    height: 240
    title: qsTr("PyQt5 love QML")
    color: "whitesmoke"

    GridLayout {
        anchors.top: parent.top
        anchors.left: parent.left
        anchors.right: parent.right
        anchors.margins: 9

        columns: 4
        rows: 4
        rowSpacing: 10
        columnSpacing: 10

        Text {
            text: qsTr("First number")
        }

        // Input field of the first number
        TextField {
            id: firstNumber
        }

        Text {
            text: qsTr("Second number")
        }

        // Input field of the second number
        TextField {
            id: secondNumber
        }

        Button {
            height: 40
            Layout.fillWidth: true
            text: qsTr("Sum numbers")

            Layout.columnSpan: 2

            onClicked: {
                // Invoke the calculator slot to sum the numbers
                sumResult.text = calculator.sum(firstNumber.text, secondNumber.text)
            }
        }

        Text {
            text: qsTr("Result")
        }

        // Here we see the result of sum
        Text {
            id: sumResult
        }

        Button {
            height: 40
            Layout.fillWidth: true
            text: qsTr("Subtraction numbers")

            Layout.columnSpan: 2

            onClicked: {
                // Invoke the calculator slot to subtract the numbers
                subResult.text = calculator.sub(firstNumber.text, secondNumber.text)
            }
        }

        Text {
            text: qsTr("Result")
        }

        // Here we see the result of subtraction
        Text {
            id: subResult
        }
    }
}