references to labels in #include documents bomb on standalone

[ondohotola]

Description

I am re-doing a largeish handbook from LaTeX/LyX in typst.

In LyX the concept of “child document” allows referencing labels in other (child) documents even when compiling a (child) document standalone (for speed).

When I try to do this in typst it generates errors when the labels are missing (standalone). It works very well when doing the master document (with the required) #includes.

I would not mind a warning on compilation and perhaps an obvious text being inserted, ie bold and uppercase MISSINGLABEL in the PDF, perhaps even in red or something.

Use Case

This would allow to generate #include’d files to be compiled standalone.

[Enivex]

This should be achievable right now by creating a custom ref function that uses https://typst.app/docs/reference/meta/query/ to check for the existence of the label. Though I haven't actually tried.

It wouldn't be a bad idea to have an optional fallback value for #ref so it fails more gracefully.

[ondohotola]

Great,

could you perhaps do that? It’s way beyond my capabilities.

[Enivex]

Proof of concept:

main.typ

#set heading(numbering: "1.")

= First <test>

@test2

#include "child.typ"

child.typ

#set heading(numbering: "1.")

#let myref(label) = locate(loc =>{
    if query(label,loc).len() != 0 {
        ref(label)
    } else {
        text(fill: red)[?]
    }
})

= Second <test2>

#myref(<test>)

Compiled main.typ

Compiled child.typ

[laurmaedje]

Could probably also use a ref show rule instead of a custom ref function.

[Enivex]

Could probably also use a ref show rule instead of a custom ref function.

I considered the possibility, but I didn't know exactly how to make it work.

[ondohotola]

@Enivex posted the solution to the Discord (which I have slightly adapted:

main.typ

#set heading(numbering: "1.")
#show ref: it =>{
  if it.element == none{
    text(fill: red)[(?)]
  } else {
    it
  }
}

= First <test>

@test2

#include "child.typ"

child.typ

#set heading(numbering: "1.")

#show ref: it =>{
  if it.element == none{
    text(fill: red)[(?)]
  } else {
    it
  }
}

= Second <test2>

@test

which does the trick very nicely indeed.

Thank you very much.