[Rd] logic tweak needed for as.data.frame.<class> deprecation warning

[Mikael Jagan]

Another issue raised in the earlier thread is that as.data.frame.POSIXlt
still calls as.data.frame.POSIXct.  Hence another path to a false positive
deprecation warning would be:

 > Sys.setenv("_R_CHECK_AS_DATA_FRAME_EXPLICIT_METHOD_" = TRUE)
 > as.data.frame(as.POSIXlt(.POSIXct(0, "UTC")))
   as.POSIXlt(.POSIXct(0, "UTC"))
1                     1970-01-01
Warning message:
Direct call of 'as.data.frame.POSIXct()' is deprecated.  Use 
'as.data.frame.vector()' or 'as.data.frame()' instead

as.data.frame.POSIXlt could simply change to using as.data.frame.vector.

I glanced at the other non-deprecated as.data.frame.<class> and did not
see other usage of the deprecated ones ... a more systematic check could
be worth doing.

Mikael

On 2023-07-06 11:32 am, Mikael Jagan wrote:
> Continuing the thread started on R-package-devel, here:
> https://stat.ethz.ch/pipermail/r-package-devel/2023q3/009307.html
> 
> The logic of the now soft-deprecated as.data.frame.<class>,
> 
>   > body(as.data.frame.integer)[[2L]]
> if ((sys.nframe() <= 1L || sys.call(-1L)[[1L]] != quote(as.data.frame)) &&
>       nzchar(Sys.getenv("_R_CHECK_AS_DATA_FRAME_EXPLICIT_METHOD_")))
> .Deprecated(msg = gettextf("Direct call of '%s()' is deprecated.  Use '%s()' or
> '%s()' instead",
>       "as.data.frame.integer", "as.data.frame.vector", "as.data.frame"))
> 
> may need adjustment to avoid false positives such as this one:
> 
>   > Sys.setenv("_R_CHECK_AS_DATA_FRAME_EXPLICIT_METHOD_" = TRUE)
>   > f <- as.data.frame
>   > f(0L)
>     0L
> 1  0
> Warning message:
> Direct call of 'as.data.frame.integer()' is deprecated.  Use
> 'as.data.frame.vector()' or 'as.data.frame()' instead
> 
> i.e., the condition sys.call(-1L)[[1L]] != quote(as.data.frame) is not precise
> enough ... would !identical(sys.function(-1L), as.data.frame) work instead?
> 
> Mikael