fix broken annotate! for AnnotatedChar

[matthias314]

The function annotate! has been broken for AnnotatedChar, at least since the inclusion StyledStrings.jl into Julia 1.11:

julia> using StyledStrings; annotate!(AnnotatedChar('x'), :face, :red)
ERROR: FieldError: type NamedTuple has no field `value`, available fields: `label`, `val`
Stacktrace:
 [1] macro expansion
   @ ./namedtuple.jl:129 [inlined]
 [2] @NamedTuple{label::Symbol, value}(nt::@NamedTuple{label::Symbol, val::Symbol})
   @ Base ./namedtuple.jl:124
 [3] annotate!(c::AnnotatedChar{Char}, label::Symbol, val::Any)
   @ Base ./strings/annotated.jl:370
 [4] top-level scope
   @ REPL[1]:1

This PR fixed this:

julia> using StyledStrings; annotate!(AnnotatedChar('x'), :face, :red)
'x': ASCII/Unicode U+0078 (category Ll: Letter, lowercase)

(The red color is shown in the REPL.)

Side remark: Given that no-one can use this function at present, I wonder if one should reconsider the choice of arguments. Even if the annotations do not form a dictionary, I would see some benefit in writing

annotate!(c, label => value)

An extension to more than one annotation

annotate!(c, label1 => value1, label2 => value2)

would then be more natural.

[adienes]

Given that no-one can use this function at present, I wonder if one should reconsider the choice of arguments. Even if the annotations do not form a dictionary, I would see some benefit in writing

this sounds like a fair suggestion, but since annotate! is not public this can be done later without really caring about how breaking it is or not.

[matthias314]

annotate! is not public

Are you sure? It's in the list of public names:

julia> using StyledStrings; names(StyledStrings)
13-element Vector{Symbol}:
 Symbol("@styled_str")
 :AnnotatedChar
 :AnnotatedIOBuffer
 :AnnotatedString
 :Face
 :SimpleColor
 :StyledStrings
 :addface!
 :annotate!
 :annotatedstring
 :annotations
 :styled
 :withfaces

[adienes]

ah, you are right I was looking at Base.ispublic(Base, :annotate!) not Base.ispublic(StyledStrings, :annotate!)

[tecosaur]

The API used to be based on Pairs, but in #55249 it was advocated to switch to a NamedTuple based design (implemented in #55741).

See: https://github.com/JuliaLang/julia/pull/55741/files#diff-2f01122b48405cb66bf6b682b0cb968aa4a6d6cfd0ec6975e2114d04c583dd1cL330-R345

-    annotate!(str::AnnotatedString, [range::UnitRange{Int}], label::Symbol => value)
-    annotate!(str::SubString{AnnotatedString}, [range::UnitRange{Int}], label::Symbol => value)
+    annotate!(str::AnnotatedString, [range::UnitRange{Int}], label::Symbol, value)
+    annotate!(str::SubString{AnnotatedString}, [range::UnitRange{Int}], label::Symbol, value)

This bugfix (thanks!) seems to correct an oversight from #55741.

There is still some scope for adjusting this API, because while it is the intended point for annotations to be changed (hence the public), the AnnotatedString API as a whole has been marked as experimental while use stabilises.

https://docs.julialang.org/en/v1/manual/strings/#man-annotated-strings

The API for AnnotatedStrings is considered experimental and is subject to change between Julia versions.

We should discuss whether any changes are worth it somewhere else though I think, it isn't worth holding up this bugfix PR.