如何以可靠的方式使用__del__? [英] How to use __del__ in a reliable way?

问题描述

我了解到python 可以 保证，只要删除对象，就会调用__del__. 换句话说，del x 不一定必然调用它的析构函数x.__del__().

I have learned that python does not guarantee that __del__ is called whenever an object is deleted. In other words, del x does not necessarily invoke its destructor x.__del__().

如果我想确保正确清理对象，则应使用

If I want to ensure proper object cleanup, I should use a context manager (in a with statement).

我知道它很愚蠢，但是出于两个原因(请不要问为什么)，我被绑定到使用Python 2.4的系统上.因此上下文管理器毫无疑问(它们是在Python 2.5中引入的)

I know it's stupid, but for a couple of reasons (please don't ask why) I am tied to a system with Python 2.4; therefore context managers are out of question (they were introduced in Python 2.5)

因此，我需要一个替代解决方案，因此，我的问题是:是否有最佳实践可以帮助我可靠地使用__del__?我在朝着的方向思考:如果python提供了这样的功能，那么肯定有一种可以有效使用它的方式(我只是很愚蠢地想出方法)" ,,

So I need a an alternative solution, and hence my question: are there best practices that would help me to use __del__ reliably? I am thinking in the direction of "if python provides such functionality, there must be a way it can be efficiently used (I'm just to stupid to figure out how)",,,

或者我只是天真，应该忘掉__del__并转而使用一种完全不同的方法吗?

Or I am just being naive, should forget about __del__ and move on to a completely different approach?

推荐答案

简而言之:不，没有办法确保它被调用.

In short: No, there is no way to ensure it gets called.

答案是自己实施上下文管理器. with语句大致翻译为:

The answer is to implement context managers yourself. A with statement roughly translates to:

x.__enter__()
try:
    ...
finally:
    x.__exit__()

因此，只需手动进行即可.它要复杂得多，所以我建议阅读 PEP 343 来阅读充分了解上下文管理器的工作原理.

So just do it manually. It is a little more complex than that, so I recommend reading PEP 343 to fully understand how context managers work.

一种选择是调用清理函数close()，然后在将来的python版本中，人们可以轻松使用

One option is to call your cleaning up function close(), and then in future versions of python, people can easily use contextlib.closing to turn it into a real context manager.

这篇关于如何以可靠的方式使用__del__?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！