什么时候del在python中有用? [英] When is del useful in python?

问题描述

我真的想不出python为什么需要del关键字的任何原因(大多数语言似乎没有类似的关键字).例如，可以删除None而不是删除变量.从字典中删除时，可以添加del方法.

I can't really think of any reason why python needs the del keyword (and most languages seem to not have a similar keyword). For instance, rather than deleting a variable, one could just assign None to it. And when deleting from a dictionary, a del method could be added.

是否有任何理由将del保留在python中，或者这是Python的垃圾收集日的痕迹?

Is there any reason to keep del in python, or is it a vestige of Python's pre-garbage collection days?

推荐答案

首先，您可以删除除局部变量之外的其他内容

Firstly, you can del other things besides local variables

del list_item[4]
del dictionary["alpha"]

这两个都应该明显有用.其次，在局部变量上使用del可使意图更清晰.比较:

Both of which should be clearly useful. Secondly, using del on a local variable makes the intent clearer. Compare:

del foo

到

foo = None

在del foo的情况下，我知道目的是从范围中删除变量.目前尚不清楚foo = None是否正在这样做.如果有人刚刚分配了foo = None，我可能会认为这是无效代码.但是我立即知道为del foo编写代码的人想要做什么.

I know in the case of del foo that the intent is to remove the variable from scope. It's not clear that foo = None is doing that. If somebody just assigned foo = None I might think it was dead code. But I instantly know what somebody who codes del foo was trying to do.

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