R devel - Nov 2015 - R_MakeExternalPtr 'tag' argument

Most packages that use the R_MakeExternalPtr function use
Rf_install("pkgSpecificString") for its 'tag' argument (if
they don't use
R_NilValue).  A few use Rf_mkChar("pkgSpecificString").

Is there any reason to prefer one over the other?

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Nov 13, 2015, at 3:58 PM, William Dunlap <wdunlap at tibco.com> wrote:
> Most packages that use the R_MakeExternalPtr function use
> Rf_install("pkgSpecificString") for its 'tag' argument
(if they don't use
> R_NilValue).  A few use Rf_mkChar("pkgSpecificString").
> 
> Is there any reason to prefer one over the other?
> 
I think Luke is the definite authority, but IMHO using CHARSXP is illegal since
you can only store CHARSXP in STRSXP. R-exts allows "ordinary R
objects" so presumably mkString() would be legal.

Cheers,
Simon