为什么称为可空? [英] Why is it called nillable?

问题描述

在 XML 模式中，您可以将元素标记为 nillable，这意味着它可以采用显式的 NULL 值.请参阅 nillable 和 minOccurs XSD 元素属性以获得很好的解释.

In an XML schema you can mark an element as nillable meaning it can take an explicit NULL value. See nillable and minOccurs XSD element attributes for a great explanation.

我很好奇的是为什么将它称为nillable?我总是看到 nillable 并认为这是一个错字！

What I'm curious about is why is it called nillable? I always see nillable and think it's a typo!

编辑我很欣赏 nil 是 null 的同义词.我想知道的是为什么选择了 nil，而不是更常见的(在计算机科学中)null.特别是它应该是 nilable(注意单个 L)！

EDIT I appreciate that nil is a synonym for null. What I'm wondering is why nil was chosen, rather than the more common (in computer science) null. Particularly as it should really be nilable (note the single L)!

推荐答案

我想知道的是为什么选择了 nil，而不是更常见的(在计算机科学中)null

What I'm wondering is why nil was chosen, rather than the more common (in computer science) null

这取决于您来自计算机科学的哪个部分！

This depends on which part of computer science you're coming from!

如果您查看用函数式语言编写的程序，您会在任何地方看到 nil，很少看到 null.碰巧的是，XML 及其所有同级语言(例如 XSLT)都与函数式语言密切相关.

If you look at programs written in functional languages, you'll see nil every where, and very seldom null. And as it happens, XML and all it's siblings such as XSLT are closely related to functional languages.

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