当用户点击按钮时，打印点我嘎哈

from PyQt5.Qt import *

class window(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("我的窗口")
        self.resize(500,500)
        self.setup_ui()


    def setup_ui(self):
        l = QLabel(self)
        l.move(400,400)
        l.setText("这是一个标签")

        self.signalPlay()

########################################################################################
    def signalPlay(self):

        btn = QPushButton(self)
        btn.setText("点击我")
        def cao():
            print("点我嘎哈")
        btn.clicked.connect(cao)



if __name__ == '__main__':
    import sys
    App = QApplication(sys.argv)

    win = window()
    win.show()

    sys.exit(App.exec_())

在所有修改的窗口标题前，添加前缀“哈哈”

if __name__ == '__main__':
    import sys
    App = QApplication(sys.argv)

    win = QWidget()

    def cao(title):
        print("窗口标题变化了",title)
        win.windowTitleChanged.disconnect()
        #win.blockSignals(True)#临时中断连接也是可以的
        win.setWindowTitle("haha" + title)
        win.windowTitleChanged.connect(cao)
        #win.blockSignals(False)
    # 连接窗口标题变化信号与槽
    win.windowTitleChanged.connect(cao)
    win.setWindowTitle("hello my life")
    win.setWindowTitle("hello my life1")
    # win.setWindowTitle("hello my life2")
    # win.setWindowTitle("hello my life3")
    win.show()

    sys.exit(App.exec_())