Provide compat for isTRUE()

[krlmlr]

TIL that !isTRUE(structure(TRUE, bla = "blub")) on older versions of R: ropensci/tic#183 . Do we overwrite isTRUE() in this case?

isTRUE(structure(TRUE, bla = "blub"))
#> [1] FALSE

^{Created on 2019-10-01 by the reprex package (v0.3.0)}

Session info

sessionInfo()
#> R version 3.3.3 (2017-03-06)
#> Platform: x86_64-pc-linux-gnu (64-bit)
#> Running under: Ubuntu 16.04.6 LTS
#> 
#> locale:
#>  [1] LC_CTYPE=C.UTF-8       LC_NUMERIC=C           LC_TIME=C.UTF-8       
#>  [4] LC_COLLATE=C.UTF-8     LC_MONETARY=C.UTF-8    LC_MESSAGES=C.UTF-8   
#>  [7] LC_PAPER=C.UTF-8       LC_NAME=C              LC_ADDRESS=C          
#> [10] LC_TELEPHONE=C         LC_MEASUREMENT=C.UTF-8 LC_IDENTIFICATION=C   
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> loaded via a namespace (and not attached):
#>  [1] magrittr_1.5    tools_3.3.3     htmltools_0.3.6 yaml_2.2.0     
#>  [5] Rcpp_1.0.2      stringi_1.4.3   rmarkdown_1.15  highr_0.8      
#>  [9] knitr_1.25      stringr_1.4.0   xfun_0.9        digest_0.6.21  
#> [13] evaluate_0.14

[mllg]

It's not perfectly clear to me what to do here as R core has not added a function or argument, but just replaced a function with a different one.

Before: identical(x, TRUE)
Now: is.logical(x) && length(x) == 1L && !is.na(x) && x

I assume it is safe here to replace the older implementation with the newer one (at least for packages which are tested to run with recent R versions).

[krlmlr]

It feels that backporting the behavior is the right thing to do. Can we avoid warnings in R CMD check or when loading the library?

[mllg]

There should be no warning in R CMD check. What do you mean?

And there should only be a warning when attaching the package for R versions prior to R-3.5.0. I think these are fine because (a) most people do not attach backports, or they know what they are doing, and (b) these warnings are there for a reason.

[mllg]

I've pushed to master and I'm running a revdep check now.

[mllg]

Uploaded to CRAN.