It is lovely that some C level functionality will be exported in the next release!

@DavZim @lsilvest and myself just wrote up a small piece on the Rcpp Gallery on creating a data.table object from C(++).

It would be lovely to also get to do the setalloccol() from that level. I looked into its source, and Calloccolwrapper() to alloccolwrapper() and its neighbouring functions in src/assign.c

Would it be possible to export these? Maybe starting with alloccolwrapper()? I'd be happy to put a tester PR together if there is a consensus view that this may have merit. Now that R_RegisterCCallable() is called it is simple enough to add a second entry.