How to store the value of a counter in a state

Questions
1

Hi,
like mentioned in the title, I want to store the value of a counter in a state. The ultimate goal is to achieve something like the exercism package does (but it does not correspond exactly and I don’t really understand the code).
I want that code

#q("one","a")
#q("two","b")
#q("three","c")
#printstate()

give me the result

1 one
2 two
3 three
1 a
2 b
3 c

I tried to do something like

#let mycounter = counter("mc")
#let mystate = state("state", ())
#let q(a,b) = [
  #mycounter.step()
  #mystate.update(ans=>{ans.push([#context mycounter.display() #b]);ans})
  #context mycounter.display() #a \
]

#let printstate() = context {
  for a in mystate.get() [
    #a \
  ]
}

#q("one","a")
#q("two","b")
#q("three","c")

#printstate()

but, obviously, it’s not working… I get

1 one
2 two
3 three
3 a
3 b
3 c

Any help ?

Remark : I need to store the value of the counter (it can be multilevel, like 1.2.1)

2

Hi!
You need to get the counter value at the specific location, where you update your state.

I solved this by using a label.

I’m not shure if this is the best way, but it’s working.


#let mycounter = counter("mc")
#let mystate = state("state", ())
#let q(a,b) = [
  #mycounter.step()
  #label("pos-"+str(a))
  #mystate.update(ans=>{ans.push((mycounter,a,b));ans})
  #context mycounter.display() #a \
]

#let printstate() = context {
  for a in mystate.get() [
    #context a.at(0).at(label("pos-"+str(a.at(1)))).at(0) #a.at(2)\
  ]
}

#q("one","a")
#q("two","b")
#q("three","c")

#printstate()

This results in the desired output.

image
image673×835 48.6 KB

3

Thank’s @Mathemensch
It works with the example I gave, but in my real code both parameters of #q could be content, not just string. Then it’s not working. My bad.
For example

#q(lorem(120),"a")
#q(lorem(250),"b")
#q([three $1 +2$],"c")

works for line 1 and 2 (I was testing if there was a limit in the definition of labels) but not for line 3

4

I think the issue here is that you store [#context mycounter.display()] in the state, which is then evaluated wherever the state is rendered – any snippet of content with a context inside of it gets that context rendered when it is placed in the final document. The solution here is to store the displayed counter itself:

#let q(a,b) = {
  mycounter.step()
  context {
    let number = mycounter.display() // render with context of q function call
    mystate.update(ans => {
      ans.push([#number #b])         // store rendered number
      ans
    })
    [#number #a \ ]
  }
}

image
image120×205 5.54 KB

I.e. we store [1 a], instead of [#context /*...*/ a].

(See also the examples in Context – Typst Documentation)

3 Likes
5

I think the issue here is that you store [#context mycounter.display()] in the state, which is then evaluated wherever the state is rendered

I did understand the problem was not using the right context.

I will play around with your code tomorrow, but it sure looks like the solution to my problem (in this case I will tag my post as solved).

Thank’s a lot @nleanba

1 Like