S4 objects

[moodymudskipper]

Now we assume everything to be S3

con <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
x <- glue::glue_sql("a", .con = con)

constructive::construct(x)
#> "a" |>
#>   structure(
#>     class = "SQL" |>
#>       structure(package = "DBI")
#>   )
#> Error in `constructive::construct()`:
#> ! {constructive} couldn't create code that reproduces perfectly the output
#> `original` is an S4 object of class <SQL>
#> `recreated` is an S3 object of class <SQL>, a character vector
#> `original` is an S4 object of class <character>
#> `recreated` is an S3 object of class <SQL>, a character vector
#> `original` is an S4 object of class <vector>
#> `recreated` is an S3 object of class <SQL>, a character vector
#> `original` is an S4 object of class <data.frameRowLabels>
#> `recreated` is an S3 object of class <SQL>, a character vector
#> `original` is an S4 object of class <SuperClassMethod>
#> `recreated` is an S3 object of class <SQL>, a character vector
#> ℹ use `check = FALSE` to ignore this error

dput(x)
#> new("SQL", .Data = "a")

identical(x, new("SQL", .Data = "a"))
#> [1] TRUE

We cannot just fall back on dput though since it might be brittle/verbose on recursive elements.

Then of course, it would be nice to have constructors for main S4 classes, such as DBI::SQL() (in other issues/PRs)