Heading counter is always zero until numbering is set

[mathrick]

Description

Repro:

#let hnumber = context [#counter(heading).display("1. ")]
#show heading: (it) => [#context counter(heading).display("1. ") #it.body]

= First heading

#hnumber

== First subheading (but typst thinks it's #hnumber)

= Second heading

#set heading(numbering: "1. ")

= Third heading (but typst thinks it's #hnumber)

== another subheading

This renders as:

Tested on the web app (as of 2024-05-02), and locally on 0.11.0 (2bf9f95d)

Reproduction URL

No response

Operating system

Web app

Typst version

• I am using the latest version of Typst

[Enivex]

This is intentional

[mathrick]

Ok, in this case, this should be clearly documented and explained, because it's extremely confusing to stumble upon. Also, what is the reason for this behaviour?

[Enivex]

Ok, in this case, this should be clearly documented and explained, because it's extremely confusing to stumble upon. Also, what is the reason for this behaviour?

Let me ask the opposite question: Why would the counter step if numbering is not set? If it did, then I couldn't create unnumbered sections without manually decrementing the counter at the same time.

[Enivex]

I've reopened the issue, as I couldn't find this covered by the documentation. (Though I may have overlooked something)

[mathrick]

Because the counter is defined to be counting things as they occur, not "counting things, but only if you also ask for the number afterwards":

Counts through pages, elements, and more.

With the counter function, you can access and modify counters for pages, headings, figures, and more. Moreover, you can define custom counters for other things you want to count.

Since counters change throughout the course of the document, their current value is contextual. It is recommended to read the chapter on context before continuing here.

No part of the docs mention the caveat, despite explaining when exactly the heading counter is stepped, and how to reset it. It's not at all clear to me that "I want to keep my unnumbered sections actually devoid of a number, not just not displaying the number" is the correct default, especially when resetting it explicitly covered and possible without any undue work.

[Enivex]

In what situation would you want the counter to keep going, but just not display it?

[mathrick]

@Enivex: when the numbers are shown only for some of the counted items, or not a strict prefix of the heading content. That's how I originally stumbled upon it, I was writing a show rule for headings with the numbers conditionally embedded in the content being output, so it made no obvious sense to also enable numbering when it would just be redundant with what the show rule was generating.

[PgBiel]

You should step the counter before displaying it. You can check if it.numbering != none to avoid stepping twice.

[mathrick]

@PgBiel: I don't really understand what you mean by that. If the numbering is none, then that will simply result in a counter that at best counts the times it's been displayed, which is not equivalent to having a counter that actually, y'know, counts the things it's supposed to count :). numbering: (..nums) => none is a much simpler workaround, but either way it's definitely a documentation bug at the very least.