mouseMoveEvent奇怪的崩溃

Question

import  sys
from PyQt5.Qt import *

class Mwindow(QWidget):
    def __init__(self):
        super().__init__()
        self.resize(500,500)
        self.move(250,150)
        self.setup_Ui()

    def setup_Ui(self):
        self.btn = QPushButton(self)
        self.btn.setText("点击我")
        self.btn.move(230,150)

    def mousePressEvent(self, evt) :
        self.mousex = evt.globalX()
        self.mousey = evt.globalY()

        self.btn_x = self.btn.x()
        self.btn_y = self.btn.y()

    def mouseMoveEvent(self, evt2):
        print(self.mousex,self.mousey)


    def mouseReleaseEvent(self, evt3) :
        # print(self.mouse_x,self.mouse_y)
        pass


if __name__ == '__main__':
    app = QApplication(sys.argv)
    win = Mwindow()
    win.setMouseTracking(True)
    win.show()
    sys.exit(app.exec_())

上述代码运行后，进入mouseMoveEvent事件后，窗口崩溃。
debug：''Mwindow' object has no attribute 'mouse_x''
但是在mouseReleaseEvent中self.mouse_x,self.mouse_y就能正常输出
小白求解！

Answer 1

我准备学这个，嘿嘿

Answer 2

找到问题了，mousepressenent里面加个判断，避免moveevent事件触发时，mousex和mousey变量未赋值引起程序崩溃