[Rd] Depends: R (>= 4.1) for packages that use |> and \(...)

[Kurt Hornik]

>>>>> Kurt Hornik writes:

Thanks again.  All added now with c87633.

Best
-k

>>>>> Ivan Krylov via R-devel writes:
> Thanks.  I am already looking handling the 4.2.0 placeholder syntax, but
> likely will need to refactor the code I added yesterday.

> The "experimental" 4.3.0 extra placeholder feature looks like a lot of
> effort: ideally there would be a simpler way.  I'll ask on R Core.

> My guess would be that the new syntax is particularly prominently used
> in examples: if so, it would be good to also have coverage for this.  

> Best
> -k

>> Many thanks to Henrik for remembering the report in Bugzilla and to
>> Kurt for implementing the change and finding out the true number of
>> affected packages.

>> On Wed, 22 Jan 2025 15:34:41 -0500
>> Ian Farm <ian.farm using maine.edu> wrote:

>>> Would packages using the underscore placeholder with the native pipe
>>> need to also depend on R >= 4.2.0?

>> That's a good find! For the R >= 4.2 syntax, we only need to check for
>> getParseData(...)$token %in% 'PLACEHOLDER'. The R >= 4.3 syntax feature
>> is harder to test for:

>>>> As an experimental feature the placeholder _ can now also be used in
>>>> the rhs of a forward pipe |> expression as the first argument in an
>>>> extraction call, such as _$coef. More generally, it can be used as
>>>> the head of a chain of extractions, such as _$coef[[2]]. 

>> I think it might be possible to parse(text = paste('PLACEHOLDER |>',
>> grandparent_expression)) and then look at the top-level function in the
>> call, but that feels quite fragile:

>> x <- utils::getParseData(parse(f, keep.source = TRUE))
>> i <- x$token %in% "PLACEHOLDER"
>> pi <- x[i, "parent"]
>> ppi <- x[x$id %in% pi, "parent"]
>> placeholder_expressions <- utils::getParseText(x, ppi)
>> extractor_used <- vapply(placeholder_expressions, function(src) {
>> toplevel <- parse(text = paste("PLACEHOLDER |> ", src))[[1]][[1]]
>> identical(toplevel, quote(`$`)) ||
>> identical(toplevel, quote(`[`)) ||
>> identical(toplevel, quote(`[[`))
>> }, FALSE)

>> Alternatively, we may find the first child of the grandparent of the
>> placeholder. If it's the placeholder expression, then the pipe must be
>> of the form ...|> _..., which is the R >= 4.3 syntax:

>> x <- utils::getParseData(parse(f, keep.source = TRUE))
>> i <- x$token %in% "PLACEHOLDER"
>> vapply(which(i), function(i) {
>> pi <- x[i, "parent"]
>> ppi <- x[x$id %in% pi, "parent"]
>> cppi <- x[x$parent %in% ppi, "id"]
>> min(cppi) == pi
>> }, FALSE)

>> -- 
>> Best regards,
>> Ivan

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