R Under development (unstable) (2025-10-08 r88906 ucrt) -- "Unsuffered Consequences"
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> if (!requireNamespace("data.table", quietly = TRUE)) {
+   message("SKIP: data.table not available; skipping test-locked-bindings.R")
+   quit(save = "no", status = 0, runLast = FALSE)
+ }
> 
> library(data.table)
> 
> # it is possible for a end user to modify the internal objects, this is a R
> # problem. For example, if you use data.table::setDT on datasets::mtcars you can
> # modify the object. The following example worked as of 29 Aug 2025 in R 4.5.1
> # and datasets_4.5.1.
> #
> #> setDT(datasets::mtcars)
> #> set(datasets::mtcars, j = "cyl", value = 1L)
> #> stopifnot(all(mtcars[["cyl"]] == 1L))
> #> stopifnot(all(datasets::mtcars[["cyl"]] == 1L))
> 
> # medicalcoder tries to prevent this for its lookup tables.  Importally, :w
> #
> # several user friendly data sets in .onLoad.  If a end user tries to
> # modify the non-exported internal objects, only accessable via ::: then the
> # namespace is loaded _before_ anything else can be done and the data sets used
> # within the package should be preserved.
> setDT(medicalcoder:::..mdcr_internal_icd_codes..)
> x <- medicalcoder:::..mdcr_internal_icd_codes..
> 
> # bad user, don't modify things, even if you can!
> x[, icdv := 8L]
> stopifnot(medicalcoder:::..mdcr_internal_icd_codes..[, all(icdv == 8L)])
> 
> # but the good news is that when the namespace was loaded the data set that
> # needed to be provided to the user and is called within the package via
> # get_icd_codes is not modified!
> x <- medicalcoder::get_icd_codes()
> stopifnot(x[["icdv"]] %in% c(9L, 10L))
> 
> # now, what about getting at the built objects?
> # first, the ..mdcr_data_env.. is not accessable other than by :::
> library(medicalcoder)
> stopifnot(medicalcoder:::..mdcr_internal_icd_codes..[, all(icdv == 8L)])  # still bad, but...
> 
> # the environment is hard to get to
> x <- tryCatch(..mdcr_data_env.., error = function(e) e)
> stopifnot(inherits(x, "error"))
> x <- tryCatch(medicalcoder::..mdcr_data_env.., error = function(e) e)
> stopifnot(inherits(x, "error"))
> 
> x <- medicalcoder:::..mdcr_data_env..
> stopifnot(is.environment(x))
> # and modifing the data will error
> t <- tryCatch(x$icd_codes[["icdv"]] <- 11L, error = function(e) e)
> stopifnot(inherits(t, "error"))
> 
> # data.table will also fail, at first.  Note that accessing the icd_codes right
> # now it is just a data.frame
> stopifnot(
+    is.data.frame(medicalcoder:::..mdcr_data_env..$icd_codes),
+   !is.data.table(medicalcoder:::..mdcr_data_env..$icd_codes)
+ )
> 
> # an error is thrown, but the class has been modified and it is now a data.table
> t <- tryCatch(setDT(x$icd_codes), error = function(e) e)
> stopifnot(inherits(t, "error"))
> stopifnot(
+    is.data.frame(medicalcoder:::..mdcr_data_env..$icd_codes),
+    is.data.table(medicalcoder:::..mdcr_data_env..$icd_codes)
+ )
> 
> # so now, end user could modify the object and the return from get_icd_codes()
> # will reflect this change
> stopifnot(all(get_icd_codes()[["icdv"]] %in% c(9L, 10L)))
> medicalcoder:::..mdcr_data_env..$icd_codes[, icdv := 98L]
> stopifnot(all(get_icd_codes()[["icdv"]] == 98L))
> 
> # so, yeah, end users could mess things up but if someone does this that is on
> # them.  Importantly, the get_x functions use
> #
> # unserialize(serialize(x, connection = NULL))
> #
> # to ensure end users only get deep copies of the chached data sets.  One quick
> # check.
> detach("package:medicalcoder", unload = TRUE)
> library(medicalcoder)
> x <- get_icd_codes()
> setDT(x)
> y <- data.table::copy(x)
> x[, icdv := 42L]
> z <- get_icd_codes()
> 
> stopifnot(
+   all(y[["icdv"]] %in% c(9L, 10L)),
+   all(z[["icdv"]] %in% c(9L, 10L)),
+   all(x[["icdv"]] == 42L)
+ )
> 
> ################################################################################
> #                                 End of File                                  #
> ################################################################################
> 
> proc.time()
   user  system elapsed 
   6.04    0.53    6.56