Custom Numbered Blocks Extension for Quarto

This extension provides user defined custom div classes (environments) that come with numbering, such as theorems, examples, exercises. Numbered blocks can be cross referenced.

• By default, the div's text block is enclosed in a collapsible box, similar to quarto callouts.
• Groups of classes can be defined that share style and numbering.
• Lists-of-classes can be extracted, such as a list of all theorems. It is also possible to generate a list for a group of classes.

The filter supports output formats pdf and html.

Status

Seems that Quarto 1.3 handles pdf books differently from Quarto 1.2. If chapters contain additional level 1 heading, this messes up numbering in Quarto 1.3 pdf books. I will likely fix that soon.

There may come changes to the yaml-UI for lists-of-classes, also soon ;-).

Installing

quarto add ute/custom-numbered-blocks

This will install the extension under the _extensions subdirectory. If you're using version control, you will want to check in this directory.

Using

Usage is illustrated more comprehensively in example.qmd.

Defining and using a user defined class

To specify a new class of numbered div blocks, Example, say, add yaml code:

custom-numbered-blocks:
  classes:
    Example: default

Use the class in a fenced dive. Title can be provided as a header immediately after div.

::: Example
### the best possible example, ever
here is some exemplary text
:::  

Change default options for a class

The default style renders as a collapsible box with title button, similar to quarto callouts. It comes with a small close button bottom right. You can change the following options in yaml or individually in the div specification:

• colors : an array of two hex rgb color codes, for title button color and frame color. colors: [a08080, 500000] would give a pink title button and dark red frame.
• collapse: boolean, default true. Initial state of the collapsible box.
• label: the label to print before the number (string).
• boxstyle: set to foldbox.simple for a boxed environment without close button. There will quite likely come more options in a future version.
• listin: register for a list-of

Groups of classes with joint counter and joint default style

Jointly counted block classes are specified by yaml option groups. These groups can also have a common default style. For each class, option group indicates membership.

Example: we want to jointly count theorems, lemmas and propositions, and render boxes with initially open status, but propositions should be collapsed:

custom-numbered-blocks:
  groups:
    thmlike:
      collapse: false
  classes:
    Theorem:
      group: thmlike
    Proposition:
      group: thmlike
      collapse: true
    Lemma:
      group: thmlike                  

Lists-of ("listin" version)

To generate a list of all divs belonging to a class, Example, say, add key listin to the class and give the name of the list. The same can be done for groups of classes. This will produce a file list-of-name.qmd that contains headers and references to the respective blocks. The following code will generage files list-of-allthingsmath.qmd and list-of-examples.qmd:

custom-numbered-blocks
  groups:
    thmlike:
      collapse: false
      listin: [allthingsmath]
    Example:
      listin: [examples, allthingsmath] 

Example

Here is the source code for a (not so) minimal example: example.qmd. And here's the rendered example.html and example.pdf

Limitations

• References to bibliography in the title are not resolved, see this issue by ntq2022. This is due to the sequence of processing references. Pull requests are welcome - I am not sure if I will have time to dig into this in the nearer future.
• Cross-reference labels that are interpretable for Quarto, such as labels starting with thm- or fig-, cannot be used with this extension, since they will be processed by Quarto. This results in unexpected output, see this issue by gyu-eun-lee.

Workarounds and precautions to avoid clashes with other extensions

• If you use parse-latex, make sure that custom-numbered-blocks comes first in the filter pipeline to process LaTeX references (\ref).
• Further headers within custom numbered blocks will mess up indentation of paragraphs following that block. To avoid that, include headers in a div, for example

  ::: {.myblock}
  ### heading of my custom block
  blabla
  
  ::::{}
  ### new header
  ::::
  other stuff