Fenced code? about remark-attr

[arobase-che]

Hi \o

I just didn't implement it. It a new syntax and it need a complete parser for fenced code.

However i should be able to implement that syntax :

```html
<p>Hello !</p>
```
{ style="..." }

Which is more consistent with the syntax of the other non-inline (block) elements.

About the first syntax, someone should talk with the creator of remark about that.

[Hypercubed]

Are you saying you think the fenced code syntax should be:

```html
<p>Hello !</p>
```
{ style="..." }

vs:

```html { style="..." }
<p>Hello !</p>
```

Any strong reason for one over the other?

I currently using a custom remark plugin to handle:

```html 'class="..."'
<p>Hello !</p>
```

I'd prefer to use remark-attr.

[arobase-che]

Are you saying you think the fenced code syntax should be:

Yes, you got my point :)

Any strong reason for one over the other?

Strong, maybe not but at least there are reasons.

With markdown, there are 2 types of elements. Block and span. This plugin add a bracket custom markdown attributes syntax which is placed at the end of the original syntax. On the same line for span element and to the next line for block element.

# Here a title
{ type="block" }

*Please, chance it.*{ author="malcolm" type="span" }

Another reason is that i don't know if the syntax :

~~~lang { attr="val" }

Is in use. I know that Pandoc use something similar, but i far as i know it is something like that :

```{ lang="c" attr="val"}

Pandoc is also compatible with :

~~~lang

But can we mix it ? I don't know.

And finally, they is that info string syntax.

~~~lang attr=val attr2=val

info string is used in Github Flavored Markdown and CommonMark so i think it's a common syntax. However, remark doesn't support it at the moment. Maybe i should make a PR about it.

Mixing info string syntax with the Pandoc one will look ugly as :

```lang attr=val attr2='val' { attr='otherVal' attr3=yes }

And I preferred not to.

That's my point. I'm interested in yours. :)

Edit: Bad english 🤦‍♀️

[Hypercubed]

Hmm... a couple of comments:

I would prefer the attrs be after the language only for readability.

~~~lang { attr="val" }

The pandoc syntax is not very useful since it will interfere with syntax editors.

It looks like the info string in GFM is pretty much only used for the language.

[arobase-che]

Hummm ...

Ok. I put it on my todo-list. I don't guaranty anything, but i will try something.

[Hypercubed]

I'm willing and able to contribute... as long as we have a good idea of the syntax.

[arobase-che]

👍

The syntax ?

~~~ lang { attr="val" }

The one you talked about.

Where '{ attr="val" }' is a info string, that's the trick, the parsing of the info string can be made by md-attr-parser. As it's coded, it will handle both 'attr="val"' and '{ attr="val"}', which is pretty cool.
So info string should be support by remark first. I made a issue about that : remarkjs/remark#342, it's easy to implement by it had to be merged first.

So both of the syntax will be supported by the plugin :

~~~haskell { start_line=2 }
f x = 2*x
~~~

and

~~~haskell start_line=2
f x = 2*x
~~~

And a fallback support of the suffixed custom attributes for block. Kind of like kramdown does.
It's a short commit to that plugin.

The hardest thing will be the configuration.

What do you think ?

[Hypercubed]

I'm really not sure what support is needed from remark itself. Currently for fenced code like ~~~haskell { start_line=2 } the intire string after the tripple tick is interpreted as the language (so here node.lang = "haskell { start_line=2 }". I belive we would need nothing more than to extract the attr portion from the language string (aka info string). Am I oversimplifying this? I'm sure you have been working with remark for a lot longer than me.

[arobase-che]

Hahah, that's true. But it look like a bug to me.

In fact, now, fenced code like ~~~haskell { start_line=2 } will break others plugins like remark-highlight.js. So we can't exploit the fact that remark missparse lang. But as we can see, implement a info string support to remark will be easy.

[Hypercubed]

I could be wrong but appears to me that in this example ~~~haskell { start_line=2 } the info string is "haskell { start_line=2 }" and remark is placing the entire info string in lang property (maybe poorly named in that case). So the bug is in remark-highlight.js that doesn't correctly parse the info string.

From the GFM spec:

The first word of the info string is typically used to specify the language of the code sample, and rendered in the class attribute of the code tag.

[arobase-che]

Oh !

You have definitively right ! ... By the end of the WE ... 😉

Thanks :)

[Hypercubed]

Looking at the CommonMark spec and the CommonMark demo also leads me to believe that the entire string is the info string:

https://spec.commonmark.org/dingus/?text=%60%60%60this%20is%20all%20info%20string%0Asdfasdf%0A%60%60%60

Notice that the generated AST is <code_block info="this is all info string">

[arobase-che]

Humm, now they is some new tests about this feature. Also, the upcoming version of remark is already supported. Only the syntax :

~~~lang { attr="val" }

is supported. Not this one :

~~~{ land attr="val" }
~~~

Nore this one :

~~~
~~~
{lang attr="qsdqsd"}
~~~~

The reason to this is to not break compatibility with others markdown engine that only support the `lang` attribute.