为什么 --- (3 个破折号/连字符)在 yaml 文件中? [英] why --- (3 dashes/hyphen) in yaml file?

问题描述

所以我刚开始使用 YAML 文件而不是 application.properties 因为它更具可读性.我在 YAML 文件中看到它们以 --- 开头.我用谷歌搜索并找到了以下解释.

So I just started using YAML file instead of application.properties as it is more readable. I see in YAML files they start with ---. I googled and found the below explanation.

YAML 使用三个破折号(---")将指令与文档分开内容.如果没有，这也用于表示文档的开始存在指令.

YAML uses three dashes ("---") to separate directives from document content. This also serves to signal the start of a document if no directives are present.

此外，我尝试了一个没有 --- 的示例，并了解到拥有它们并不是强制性的.

Also, I tried a sample without --- and understood that it is not mandatory to have them.

我想我对directive 和document 的理解不是很清楚.谁能用一个简单的例子解释一下?

I think I don't have a clear understanding of directive and document. Can anyone please explain with a simple example?

推荐答案

正如您已经发现的，三个破折号 --- 用于表示文档的开始强>，即:

As you already found out, the three dashes --- are used to signal the start of a document, i.e.:

1. 根据当前规范，在指令之后(即%YAML或%TAG行)通知文档开始.例如:

1. To signal the document start after directives, i.e., %YAML or %TAG lines according to the current spec. For example:

%YAML 1.2
%TAG !foo! !foo-types/
---
myKey: myValue

要在同一流中有多个 yaml 文档(例如一个 yaml 文件)时发出文档开始的信号:

To signal the document start when you have multiple yaml documents in the same stream, e.g., a yaml file:

doc 1
---
doc 2

如果 doc 2 有一些前面的指令，那么我们必须使用三个点 ... 来向解析器指示 doc 1 的结束(以及 doc 2 之前的潜在指令的开始).例如:

If doc 2 has some preceding directives, then we have to use three dots ... to indicate the end of doc 1 (and the start of potential directives preceding doc 2) to the parser. For example:

doc 1
...
%TAG !bar! !bar-types/
---
doc 2

该规范适用于 yaml 解析器实现者.但是，我发现这篇文章从用户的角度更易于阅读.

The spec is good for yaml parser implementers. However, I find this article easier to read from a user perspective.

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