Feature request: add support for <..>-arguments of environments

[buzden]

For example, to support generation of

\begin{uncoverenv}<3->
...
\end{uncoverenv}

[chdemko]

That's a good idea. Could it be possible to propose a Pull request ?

[buzden]

Yes, it could. The question is in the design. What I came with by experimenting is a bit more general solution (TBH, I impelemented it as a lua-script) and it is the following: we could support all types of the arguments in any order the user wishes, so that, say

``` {.env on=whatever}
...
```

translates to

\begin{env}<whatever>
...
\end{env}

and

``` {.env arg=whatever}
...
```

translates to

\begin{env}{whatever}
...
\end{env}

and

``` {.env opt=whatever}
...
```

translates to

\begin{env}[whatever]
...
\end{env}

But any longer combinations are also possible:

``` {.env arg=w1 arg=w2 on=w3 opt=w4}
...
```

translates to

\begin{env}{w1}{w2}<w3>[w4]
...
\end{env}

and etc.

Are you okay with such design?

[chdemko]

I think I'm globally ok but it lacks some features:

``` {#identifier .env arg=w1 arg=w2 on=w3 opt=w4 convert.arg="*italic*" convert.opt="**bold**"}
...
```

should be translates to

\begin{env}{w1}{w2}{\emph{italic}}<w3>[w4][\textbf{bold}]\label{identifier}
...
\end{env}

This is already the case with the title argument.

[chdemko]

The issue is that I use panflute to parse the data and panflute considers attributes as a python dict (without duplicates). See http://scorreia.com/software/panflute/code.html#panflute.elements.Div.

>>> from panflute import convert_text
>>> convert_text("""
... ::: {.env arg=a arg=b}
... :::
... """
... )
[Div(; classes=['env'], attributes={'arg': 'b'})]
>>> 

This supposes to use another way for parsing the JSON produced by pandoc:

• by parsing the JSON directly (bad idea)
• by adding some specification in the environment definition:

---
pandoc-latex-environment:
  test:
    classes: [class1, class2]
    args:
      - name: title
        convert: true
      - name: subtitle
        optional: true
      - name: other
---

``` {#identifier .class1 .class2 other="**other**" title="**mytitle**" subtitle="*subtitle*" overlay="1-3"}
...
```

should be converted to:

\begin{test}{\textbf{mytitle}}{**other**}<1-3>[*subtitle*]\label{identifier}
...
\end{test}

[chdemko]

When studying https://texdoc.org/serve/xparse/0, it seems that we should have a clear way to use these LaTeX3 new feature