如何知道对象是否在 Python 中被删除 [英] How to know if object gets deleted in Python

问题描述

我在堆中有一个对象和对它的引用.在某些情况下，对象会被删除，但指向其位置的引用并不知道这一点.如何检查堆中是否有真实数据?

I have an object in the heap and a reference to it. There are certain circumstances in which the object gets deleted but the reference that points to its location doesn't know that. How can I check if there is real data in the heap?

例如:

from PySide import *
a = QProgressBar()
b = QProgressBar()
self.setIndexWidget(index,a)
self.setIndexWidget(index,b)

然后 a 对象被删除但 print(a) 返回一个有效地址.但是，如果您尝试 a.value() - 会发生运行时错误(C++ 对象已删除).

Then the a object gets deleted but print(a) returns a valid address. However if you try a.value() - runtime error occurs (C++ object already deleted).

a is None 返回 False.

推荐答案

使用 sip 模块，阅读更多关于 sip 这里

use sip module, read more about sip here

import sip

a = QProgressBar()
sip.isdeleted(a)
False

sip.delete(a)
a
<PyQt4.QtCore.QObject object at 0x017CCA98>

sip.isdeleted(a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: underlying C/C++ object has been deleted

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