在一行中将锚和别名组合在一起会触发parserError:'Expected< block end&gt ;，但找到了'< alias>'

问题描述

我正在尝试结合使用锚和别名，以便将值重复使用不同名称的多个容器中.

I am trying to combine anchors and aliases in order to reuse values into several containers, under different names.

我尝试了以下代码:

FWL_GV_NANSEN: &fwl_gv_nansen
  dtype: float
  value: 2715.0

FWL_GV_E3_2: &fwl_gv_e32 *fwl_gv_nansen

我们的目标仅仅是让另一个变量FWL_GV_E3_2包含与FWL_GV_NANSEN相同的信息，稍后我将对此进行引用.

the goal is simply to have another variable FWL_GV_E3_2 containing the same information than FWL_GV_NANSEN that I could refer to later on.

与在Python(或其他版本)中定义的相同:

Just the same than defining in Python (or other):

a = 5.0
b = a
c = b

但这会触发以下错误消息:

But this triggers the following error message:

没有办法将别名的内容分配给用于定义新锚点的变量(通过不同的变量传播初始值吗?

Is there no way to assign the content of aliases to variable used to defined a new anchor (propagating the initial values through different variables?

PS:也许YAML并不是最好的语言，因为例如使用python的变量将是微不足道的，但是我必须使用YAML

PS: maybe YAML is not the best language for this since it would be trivial using python's variables for example but I have to use YAML

推荐答案

YAML节点属性(即标记和锚点)只能出现在真实"节点上:集合(块或流)或标量.

The YAML node properties (i.e. tags and anchors) can only occur on "real" nodes: collections (block or flow) or scalars.

从生产规则中可以看到， c-ns-properties 仅可在此处使用，但别名部分也明确声明:

You can see from the production rules that c-ns-properties can be used only there, but section for aliases also states explicitly:

---

如果您的YAML解析器允许您访问原始锚点/别名或某些锚点到节点/对象的映射(例如我的 ruamel.yaml ，>用于往返的Python软件包)是使用带标记的标量:

---

What is possible if your YAML parser gives you access to the original anchor/aliases, or some anchor-to-node/object mapping (such as my ruamel.yaml package for Python when used for round-tripping), is to use a tagged scalar:

FWL_GV_NANSEN: &fwl_gv_nansen
  dtype: float
  value: 2715.0

FWL_GV_E3_2: &fwl_gv_e32 !ref fwl_gv_nansen

使用！ref 对象的构造函数解析标量 fwl_gv_nansen 的标量，并带有一些 application 特定代码.通常，锚和别名事件是在作曲之前由作曲程序加载程序步骤 解决的(如果这样，则不再可用信息).

with the constructor of the !ref object resolving the scalar fwl_gv_nansen, with some application specific code. Normally the anchor and alias events are resolved by the composer loader step before composing (and if so that information is no longer available).

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