[r] Check that TileDB Core library versions match (#2410)

* [r] Check that library versions match

* Also enable .onAttach()

apis/r/R/Init.R

@@ -0,0 +1,25 @@
+## .onLoad is called whether code from the package is used and the packages is 'loaded'. An
+## example is calling `tiledbsoma::show_package_versions()`. So this is most elementary check,
+## .onAttach is also called when the package is 'attached' via 'library(tiledbsoma)'
+## During package build and byte-code compilation and load check, both are called.
+.onLoad <- function(libname, pkgname) {
+    rpkg_lib_version <- tiledb::tiledb_version(compact=TRUE)
+    soma_lib_version <- libtiledbsoma_version(compact=TRUE)
+    if (rpkg_lib_version != soma_lib_version) {
+        msg <- sprintf("TileDB Core version %s used by TileDB-R package, but TileDB-SOMA uses %s",
+                       sQuote(rpkg_lib_version), sQuote(soma_lib_version))
+        stop(msg, call. = FALSE)
+    }
+}
+
+## An .onAttach() function is not allowed to use cat() etc but _must_ communicate via
+## packageStartupMessage() as this function can be 'muzzled' as desired. See Writing R Extensions.
+.onAttach <- function(libname, pkgname) {
+    if (interactive()) {
+        packageStartupMessage("TileDB-SOMA R package ", packageVersion(pkgname),
+                              " with TileDB Embedded ", format(tiledb::tiledb_version(TRUE)),
+                              " on ", utils::osVersion,
+                              ".\nSee https://github.com/single-cell-data for more information ",
+                              "about the SOMA project.")
+    }
+}