How to pass arguments to callback functions in PyQt

Question

I have around 10 QAction (this number will vary in runtime) in a toolbar, which all will do same thing, but using different parameters. I am thinking to add parameter as an

Answer 1

The best way to pass the arguments is to not pass them at all. You can use the dynamic nature of python, and set whatever data you need as your own properties on the widgets themselves, get the target widget in the handler using self.sender(), and then get whatever properties you need directly from the widget.

In this example five buttons are created and the required state is set on the button widget as my_own_data property:

import sys
from PyQt4 import QtGui, QtCore

class Main(QtGui.QMainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.centralwidget = QtGui.QWidget()
        self.vboxlayout = QtGui.QVBoxLayout()

        for idx in range(5):
            button = QtGui.QPushButton('button ' + str(idx), None)
            button.my_own_data = str(idx)  # <<< set your own property
            button.clicked.connect(self.click_handler)  # <<< no args needed
            self.vboxlayout.addWidget(button)

        self.centralwidget.setLayout(self.vboxlayout)
        self.setCentralWidget(self.centralwidget)
        self.show()

    def click_handler(self, data=None):
        if not data:
            target = self.sender()  # <<< get the event target, i.e. the button widget
            data = target.my_own_data  # <<< get your own property
        QtGui.QMessageBox.information(self, 
                                      "you clicked me!", 
                                      "my index is {0}".format(data))

app = QtGui.QApplication(sys.argv)
main = Main()
main.show()

sys.exit(app.exec_())