Using flex-caption from a template yields long captions instead of short

Questions
1

Version/platform info: typst version: 0.14.0 (dd1e6e94) (typst-aarch64-apple-darwin)

Various examples online define a flex-caption function to generate long vs short captions for “List of Figures” outlines. I cannot get it to work properly when doing #import.

I have two files: lib_mwe.typ

#let in-outline = state("in-outline", false)

#show outline: it => {
    in-outline.update(true)
    it
    in-outline.update(false)
}

#let flex-caption(short: none, long: none) = context if state("in-outline", false).get() {
    short
} else { long }

#let custom-outline(..args) = {
    show outline: set heading(outlined: true)
    outline(..args)
}

and main.typ

#import("./lib_mwe.typ"): *

#outline()
#pagebreak()

#custom-outline(title: "List of Figures", target: figure.where(kind: image))
#pagebreak()

#figure(
    image("./image.png", width: 60%),
    caption: flex-caption(
        short: [short caption],
        long: [long caption],
    )
)

Compiling main.typ gives me the “long” caption" in the “List of figures” instead of the “short caption”.
Copy-pasting the contents of lib_mwe.typ into main.typ yields the desired behavior. I suspect state-related issues are at play, but they are beyond me at this point.

2

The reason is actually not about state, but about styles and templates. import just imports the functions and definitions from lib_mwe.typ. The style you applied in the lib file with show has no effect outside its own file.

The full documentation for how to define a style (a template) in one file and use it in another is here: Making a Template – Typst Documentation

You’d need to turn this into a template:

#show outline: it => {
    in-outline.update(true)
    it
    in-outline.update(false)
}

So that you can import a function for that and apply it to your actual document in main.typ.

As an alternative to turning it into a template, the style would need to be applied inside a function like for example the custom-outline function. Then it would have effect there.

1 Like
3

Thanks for the quick feedback. I’ve tried replacing the bare #show outline directive in lib_mwe.typ with

#let template-outline = it => {
    in-outline.update(true)
    it
    in-outline.update(false)
}

and then in main.typ

#import("./lib_mwe.typ"): *
#show: template-outline

and this seems to have worked. Is this what you meant? Is there a way that would not require calling #show within main.typ?

4

That’s not quite equivalent, this is the style you want to apply:

#show outline: it => {
  in-outline.update(true)
  it
  in-outline.update(false)
}

And now we write a function that applies this style to a document:

#let template(doc) = {
  show outline: it => {
    in-outline.update(true)
    it
    in-outline.update(false)
  }
  doc
}

As an alternative to turning it into a template, the style would need to be applied inside a function like for example the custom-outline function. Then it would have effect there.

6

Hey there. Make sure you carefully read How to post in the Questions category before posting questions. The post can be edited.

7

So this did indeed work, thanks. But I’m unclear what it does differently than my template-outline suggestion. When using your template function, I still needed to do #show template in main.typ. Is this expected? If so, why would typst require (seemingly, from my naive perspective) duplicated show calls (within template and in main.typ) ? At the risk of derailing this question, I guess I also don’t understand how to use the doc argument to template.

8

In this code, when you call #show: template-outline then it is the document. But originally, it was just the outline. That’s why the translation was not equivalent. It could have been made equivalent by applying it as #show outline: template-outline but I wanted to show you how to make a proper template instead.

Yes

They shouldn’t really be duplicated. The original one you had moves into a function, where it’s not used, only defined. Then you use show in main.typ to invoke that template. Maybe that makes sense?

9

Interesting, this made me understand a nuance of #show that had so far eluded me.

yes. thanks again.