How does Signal and slot works in this code

Anmol

import sys
from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton

class MainWindow(QMainWindow):
  def __init__(self):
    super().__init__()

    self.setWindowTitle("My App")
    button = QPushButton("Press Me!")
    button.setCheckable(True)

    button.clicked.connect(self.the_button_was_toggled)
    
    # Set the central widget of the Window.
    self.setCentralWidget(button)

  def the_button_was_toggled(self, checked): # from where value of variable checked is coming and how?
    print("Checked?", checked)

app = QApplication(sys.argv)
window = MainWindow()
window.show()

app.exec()

How does this code know the state of the button's checked value. From where it is accessing variable buttons and how

jsulm

@Anmol Just look at the signal documentation: https://doc.qt.io/qt-6/qabstractbutton.html#clicked
As you can see the signal has checked parameter which is passed to the slot.

Ronel_qtmaster

@Anmol if checked == true the button is checked, otherwise it is not checked. So depending on the value of checked bool variable you can apply some actions

Anmol

@jsulm ahh.. got it 😄. Thank you