garbage-collection - PyQt:RuntimeError:包装的C/C++对象已被删除

Question

如果我运行此代码:

    #!/usr/local/bin/    python3

import sys 
from PyQt4.QtCore import *
from PyQt4.QtGui import *


class Window(QMainWindow):

    def __init__(self):
        super().__init__()
        self.button1 = QPushButton("1")
        self.button2 = QPushButton("2")
        self.setCentralWidget(self.button1)
        self.button1.clicked.connect(lambda: self.setCentralWidget(self.button2))
        self.button2.clicked.connect(lambda: self.setCentralWidget(self.button1))
        self.show()

if __name__ == '__main__':

    import sys 
    app = QApplication(sys.argv)
    window = Window()
    sys.exit(app.exec_())

...我得到以下输出:

Traceback (most recent call last):
  File "test.py", line 16, in <lambda>
    self.button2.clicked.connect(lambda: self.setCentralWidget(self.button1))
RuntimeError: wrapped C/C++ object of type QPushButton has been deleted

我不明白为什么要删除该对象。窗口应保留对此的引用。
我已经彻底调查了这些帖子:
Understanding the “underlying C/C++ object has been deleted” error
Can a PyQt4 QObject be queried to determine if the underlying C++ instance has been destroyed?

为什么删除按钮？

Answer 1

这个问题的答案如下:
Python PySide (Internal c++ Object Already Deleted)

显然，使用setCentralWidget将一个小部件分配给QMainWindow，然后使用setCentralWidget分配另一个小部件将导致基础c++ QWidget被删除，即使我有一个对象保持对其的引用。

Note: QMainWindow takes ownership of the widget pointer and deletes it at the appropriate time.