Turn off 'theorems' Lua filter when exporting to PDF

[knightgu]

I am using Quarto to write homework assignments with the LaTeX exam document class. The exam class has already defined a solution environment which can be used to show or hide the solutions with the class option answers. The problem I am running into is that when I export the document to PDF, Quarto always applies the Lua filter theorems.lua located in src/resources/filters/crossref/theorems.lua which adds a line \newtheorem*{solution}{Solution} to the exported LaTeX document and which causes LaTeX compilation error for duplicated definition. Moreover, in the exported LaTeX document, I see nested solution environments generated from the closure ::: {.solution} ... ::: (possibly due to both theorems and latex-environment filters being applied). I am wondering how I can turn off the theorems filter. Here is a minimal non-working example.

---
title: "Homework One"
format:
  pdf:
    documentclass: exam
    classoption: [12pt]
    pdf-engine: pdflatex
    filters:
      - latex-environment.lua
    environments: [questions, parts, solution]
    commands: [question, part]
  latex:
    documentclass: exam
    classoption: [12pt]
    pdf-engine: pdflatex
    filters:
      - latex-environment.lua
    environments: [questions, parts, solution]
    commands: [question, part]
---

::: {.questions}

[]{.question} Question 1

:::: {.parts}

[]{.part} 2.22 (p. 30)

::::: {.solution}
This is a very tricky problem.
:::::

::::

:::

[cscheid]

We don't generally support arbitrary documentclasses because they're not typically compatible with each other.

Some possible approaches, from most general to least:

• create a custom quarto format based on exam but changing the actual environments being defined in the template
• use a separate Lua filter (since you already have one) to fix the nested div issue. This is likely going to have to be a post filter, so your invocation will be something like:

  •  filters:
       - latex_environment.lua
       - quarto # this is where quarto's theorems processing happens
       - fixup_nested_div.lua

• use pandoc raw blocks to undefine/redefine the latex environment as needed at the beginning of your document.

[knightgu]

Thank you for the suggestions. I totally understand the difficulty to support all the documentclasses in LaTeX. It is also not the main focus of Quarto. My workaround is similar to your first suggested approach. Basically, I renamed the solution environment of the exam class in the preamble which solved the nested div issue. However, the \newtheorem*{solution}{Solution} line is still being added during exporting. My current approach removes this line from the exported LaTeX using sed and then compiles the edited LaTeX to PDF. This works (and could probably also be achieved via an ad-hoc Lua filter as you suggested) but I still feel it better to probably be able to turn off the theorems Lua filter directly in the YAML. This could open up many possibilities.

[cderv]

@cscheid this is something we needed to handle in bookdown for some specific format that defines their own environment. I believe we will need that to support more Journal format that will have this constraint.

What we did in bookdown was having a flag to prevent the insertion of the definition. It was the user responsibility to then define the environment in used if not done already by a documentclass or other tool. I feel we could at least do that.

bookdown has also a detection mechanism by parsing the tex file to detect if a user has already manually define some environment. In that case not inclusion is done. Just another example.

IMO we should consider