Use SGML Processing Instructions to pass arguments to render hooks

[bep]

This is just me thinking out loud during Christmas. I kind of like the simplicity of it. The idea is to use SGML Processing Instructions as a way to pass parameters to the new and shiny render hooks in Hugo (images and links).

• CommonMark has a proposed/experimental syntax for Markdown attributes. Goldmark has implemented it for titles and code blocks, but the Goldmark author have said that it would be "very hard" to implement it as a general thing for all elements.
• The nice thing about using SGML Processing Instructions is that most Markdown renderers (including GitHub) just ignore them (they will not get rendered).

One example would maybe look like this:

<?params width="400" height="500" ?>
![alt text](https://github.com/adam-p/markdown-here/raw/master/src/common/images/icon48.png "Logo Title Text 1")

I suggest that we:

• Agree on 1 instruction name, for now, e.g. params.
• I think it should work if we just create a stack of length 1 and pop any element into the rendering hook.

/cc @regisphilibert

[regisphilibert]

Looks promising in the long term. My feeling though is that Markdown will eventually be just one option among the many #6310 will open to Hugo users. So "roadmap wise" I woudn't put this in front of #6310.

[bep]

The road map is also budget constrained. This issue may be easier to finance (cheaper to implement).

[jmooring]

With https://github.com/gohugoio/hugo/commit/cd0c5d7ef32cbd570af00c50ce760452381df64e you can pass arguments (attributes) to heading render hooks:

# My Heading {data-foo="a" data-bar="b"}

The attributes are accessible within the heading render hook via .Attributes.

{{ range $k, $v := .Attributes }}
  {{ $k }} = {{ $v }}<br>
{{ end }}

However, you cannot do the same with either image render hooks or link render hooks because attribute support is limited to headings and blocks (see https://github.com/gohugoio/hugo/commit/2681633db8d340d2dc59cf801419874d572fc704).

[celestehorgan]

I would looooooove this for formatting table columns and the like 🤩

[bep]

@celestehorgan Hugo do have support for CommonMark attributes now (you need to enable it in config), so you should at least be able to set CSS classes on the table element.

[dfl]

With cd0c5d7 you can pass arguments (attributes) to heading render hooks:

# My Heading {data-foo="a" data-bar="b"}

The attributes are accessible within the heading render hook via .Attributes.

{{ range $k, $v := .Attributes }}
  {{ $k }} = {{ $v }}<br>
{{ end }}

However, you cannot do the same with either image render hooks or link render hooks because attribute support is limited to headings and blocks (see 2681633).

I'm really confused because the configuration markup page for render-hook templates says "Attributes (map) New in v0.82.0." under context for render-link and render-image. It really makes logical sense, can't wait for this feature to just simply work out of the box.

[chalin]

Was this closed because it won't be fixed or because it has been implemented? The text above shows "@bep closed this as completed" but I'm not seeing any linked commit or other information that would give evidence of this feature now being supported. Thanks!

[bep]

Was this closed because it won't be fixed or because it has been implemented?

We now have Markdown attributes that solves this:

https://gohugo.io/getting-started/glossary/#markdown-attribute

And yes, I should have commented on this before closing, I sometimes forget that other people watches these issues.

[github-actions[bot]]

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