Strange formatting of AsIs list columns about pillar

[hadley]

Potentially AsIs could be used with anything, so I think we just need a .AsIs() method somewhere that just calls NextMethod()

[krlmlr]

Tried adding pillar_shaft.AsIs() to no avail -- it's handled by pillar_shaft.default() anyway which calls as.character() on the input:

as.character(I(list(1, 1:2, 1:3)))
#> [1] "1"   "1:2" "1:3"

Code:

pillar/R/shaft.R

Lines 134 to 138 in be24a37

	#' @export
	#' @rdname pillar_shaft
	pillar_shaft.default <- function(x, ...) {
	pillar_shaft(as.character(x), ...)
	}

We'd need to strip the "AsIs" class from the object's classes, but somehow this smells like a bad idea. Please advise.

[hadley]

You're sure this doesn't work?

pillar_shaft.AsIs <- function(x, ...) {
  NextMethod()
}

Oh, because list isn't in the class vector?

[krlmlr]

We could do

#' @export
#' @rdname pillar_shaft
pillar_shaft.AsIs <- function(x, ...) {
  pillar_shaft.list(x, ...)
}

or (more generally)

#' @export
#' @rdname pillar_shaft
pillar_shaft.default <- function(x, ...) {
  if (is.list(x)) pillar_shaft.list(x, ...)
  else pillar_shaft(as.character(x), ...)
}

But then:

pillar::colonnade(list(a = 1:3, b = I(list(1, 1:2, 1:3, c(1:3,3)))))
#>       a b         
#>   <int> <S3: AsIs>
#> 1     1 <S3: AsIs>
#> 2     2 <S3: AsIs>
#> 3     3 <S3: AsIs>

Or we strip the class manually:

#' @export
#' @rdname pillar_shaft
pillar_shaft.AsIs <- function(x, ...) {
  if (all(class(x) == "AsIs")) {
    class(x) <- NULL
  } else {
    class(x) <- setdiff(class(x), "AsIs")
  }
  pillar_shaft(x, ...)
}

That one looks better, but I'm not sure if this is a safe approach:

pillar::colonnade(list(a = 1:3, b = I(list(1, 1:2, 1:3, c(1:3,3)))))
#>       a b         
#>   <int> <S3: AsIs>
#> 1     1 <dbl [1]> 
#> 2     2 <int [2]> 
#> 3     3 <int [3]> 
#> 1     1 <dbl [4]>

The NextMethod() approach doesn't change the output, because the call is forwarded to .default() and not to .list().

[hadley]

An even more general approach would be to do manual switchpatch in the default method:

#' @export
#' @rdname pillar_shaft
pillar_shaft.default <- function(x, ...) {
  switch(typeof(x),
    list = pillar_shaft.list(x, ...),
    numeric = pillar_shaft.numeric(x, ...),
    logical = pillar_shaft.logical(x, ...),
    pillar_shaft.character(x, ...),
  )
}

Then we're basically pretending that the final member of the class is always the typeof().

[krlmlr]

This works if we use switchpatch also in obj_sum.AsIs().

[hadley]

Oh yeah, that's a better idea - we either call NextMethod() or do switchpatch depending on the length of the class.

[krlmlr]

Let's keep switchpatch in mind, I haven't added it yet. Current output:

tibble::as_tibble(data.frame(a = 1:3, b = I(list(1, 1:2, 1:3))))
#> # A tibble: 3 x 2
#>       a b        
#>   <int> <I(list)>
#> 1     1 <dbl [1]>
#> 2     2 <int [2]>
#> 3     3 <int [3]>

[github-actions]

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