pyqt/basic/signals_and_slots_1d.py

import sys

from PyQt5.QtWidgets import QMainWindow, QPushButton, QApplication


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

        self.button_is_checked = False

        self.setWindowTitle("My App")

        self.button = QPushButton("Press Me!")
        self.button.setCheckable(True)
        self.button.clicked.connect(self.the_button_was_released)
        self.button.setChecked(self.button_is_checked)

        # Set the central widget of the window
        self.setCentralWidget(self.button)

    def the_button_was_released(self):
        self.button_is_checked = self.button.isChecked()

        print(self.button_is_checked)


app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec_()