在python，del或delattr中哪个更好? [英] Which is better in python, del or delattr?

问题描述

这可能很愚蠢，但已经困扰了我一段时间.

This may be silly, but it's been nagging the back of my brain for a while.

Python为我们提供了两种从对象中删除属性的内置方法，即 del 命令字和 delattr 内置函数.我更喜欢 delattr ，因为我认为它更加明确:

Python gives us two built-in ways to delete attributes from objects, the del command word and the delattr built-in function. I prefer delattr because it I think its a bit more explicit:

del foo.bar
delattr(foo, "bar")

但是我想知道它们之间是否存在内在差异.

But I'm wondering if there might be under-the-hood differences between them.

推荐答案

第一个比第二个更有效. del foo.bar编译为两个字节码指令:

The first is more efficient than the second. del foo.bar compiles to two bytecode instructions:

  2           0 LOAD_FAST                0 (foo)
              3 DELETE_ATTR              0 (bar)

delattr(foo, "bar")需要五个:

  2           0 LOAD_GLOBAL              0 (delattr)
              3 LOAD_FAST                0 (foo)
              6 LOAD_CONST               1 ('bar')
              9 CALL_FUNCTION            2
             12 POP_TOP             

这意味着第一次运行稍快更快(但这并不是一个很大的差异–在我的计算机上为.15μs).

This translates into the first running slightly faster (but it's not a huge difference – .15 μs on my machine).

就像其他人所说的那样，您真正应该只在动态确定要删除的属性时才使用第二种形式.

Like the others have said, you should really only use the second form when the attribute that you're deleting is determined dynamically.

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