How can I connect several QPushButtons to a single method?-CodePudding

In this application I want to connect each button to one method which simply display the text of the button pressed. Instead of writing three different methods for three different buttons, I thought I can pass the button itself as an argument to the method:

import sys
from PyQt5 import QtWidgets as qtw


class MyWindow(qtw.QWidget):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.initUI()


    def initUI(self):

        grid = qtw.QGridLayout()
        self.setLayout(grid)

        self.btn_1 = qtw.QPushButton('1')
        self.btn_2 = qtw.QPushButton('2')
        self.btn_3 = qtw.QPushButton('3')

        self.btn_1.clicked.connect(self.print_to_console(self.btn_1))
        self.btn_2.clicked.connect(self.print_to_console(self.btn_2))
        self.btn_3.clicked.connect(self.print_to_console(self.btn_3))

        grid.addWidget(self.btn_1)
        grid.addWidget(self.btn_2)
        grid.addWidget(self.btn_3)
    
        self.show()


    def print_to_console(self, obj):

        obj = qtw.QPushButton()

        print(obj.text())


def main():
    app = qtw.QApplication(sys.argv)
    ex = MyWindow()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

But I get here this error messsage:

Traceback (most recent call last):
  File "c:\Users\fibi\Documents\PyQt5\nine buttons\NineButtons - Kopie.py", line 48, in <module> main()
  File "c:\Users\fibi\Documents\PyQt5\nine buttons\NineButtons - Kopie.py", line 43, in main  ex = MyWindow()
  File "c:\Users\fibi\Documents\PyQt5\nine buttons\NineButtons - Kopie.py", line 10, in __init__self.initUI()
  File "c:\Users\fibi\Documents\PyQt5\nine buttons\NineButtons - Kopie.py", line 22, in initUI  
    self.btn_1.clicked.connect(self.print_to_console(self.btn_1))
TypeError: argument 1 has unexpected type 'NoneType'

Does anybody know what I'm doing wrong? Thanks for helping.

CodePudding user response：

All methods by default return None. You need to pass a callable object to the connect, so that the method can be called when the button is pressed.

so make the following changes (remove the () after self.print_to_console):

    self.btn_1.clicked.connect(self.print_to_console)
    self.btn_2.clicked.connect(self.print_to_console)
    self.btn_3.clicked.connect(self.print_to_console)

You can get the widget that sent the signal using QObject.sender(). So your print_to_console could be

 def print_to_console(self):
     obj = self.sender()
     print(obj.text())