Allow extracting title/keywords from another file

[damithc]

Can something like this made to work?

<frontmatter>
title: <include src="text.md#heading" inline />
</frontmatter>

text.md:

<span id="heading">Introduction</span>

[damithc]

@danielbrzn any thoughts?

[damithc]

To give some background: I wanted to put all information related to a topic in one file like the text.md below and then generate different presentations from it e.g., index.md, minimal.md i.e., I'm trying to achieve data-presentation separation and also trying to reduce duplication.

text.md:

<span id="heading">Introduction</span>
<span id="keywords">stub, driver</span>
<span id="path">Testing → Dev Testing → Unit Testing</span>
<span id="body">
Unit testing is ...

</span>

index.md:

<frontmatter>
title: <include src="text.md#path" inline /> - <include src="text.md#heading" inline />
keywords: <include src="text.md#keywords" inline />
</frontmatter>

%%<include src="text.md#path"  inline/>%%

## <include src="text.md#heading"  inline/>

<include src="text.md#body" />

minimal.md:

<frontmatter>
title: <include src="text.md#heading" inline />
</frontmatter>

**<include src="text.md#heading"  inline/>**

<include src="text.md#body" />

[danielbrzn]

I think this should be possible. We are currently able to include front matter from other files. However, some minor code changes are necessary to support the above behaviour.

Although, you could define front matter within text.md and then just include it within the different presentations.

[damithc]

Although, you could define front matter within text.md and then just include it within the different presentations.

That works when the whole frontmatter can be reused as is. In some cases, the different presentations of a topic might need slightly different frontmatter sections.

[damithc]

Related to #751