Python 是否对字符串进行逐个引用? [英] Does Python do slice-by-reference on strings?

问题描述

我想知道当我做类似的事情

a = "这可能是一个非常大的字符串..."b = a[:10]

创建一个新字符串或返回一个视图/迭代器

解决方案

Python 做切片-by-copy，意思是每次你切片(除了 非常琐碎的切片，例如 a[:])，它将所有数据复制到一个新的字符串对象中.

根据其中一位开发人员的说法，做出这个选择是因为

<块引用>

[slice-by-reference] 方法更复杂，更难实现并可能导致意外行为.

例如:

<前>a = "一个有 500,000 个字符的长字符串......"b = a[0]德尔阿

使用切片即复制设计，字符串 a 立即被释放.这切片作为参考设计会将 500kB 的字符串保留在内存中，尽管你只对第一个字符感兴趣.

显然，如果您绝对需要一个字符串视图，您可以使用 memoryview 对象.

I want to know if when I do something like

a = "This could be a very large string..."
b = a[:10]

a new string is created or a view/iterator is returned

解决方案

Python does slice-by-copy, meaning every time you slice (except for very trivial slices, such as a[:]), it copies all of the data into a new string object.

According to one of the developers, this choice was made because

The [slice-by-reference] approach is more complicated, harder to implement and may lead to unexpected behavior.

For example:

a = "a long string with 500,000 chars ..."
b = a[0]
del a

With the slice-as-copy design the string a is immediately freed. The slice-as-reference design would keep the 500kB string in memory although you are only interested in the first character.

Apparently, if you absolutely need a view into a string, you can use a memoryview object.

这篇关于Python 是否对字符串进行逐个引用?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！