In eddelbuettel/rcppclassic: Deprecated 'classic' 'Rcpp' 'API'

\noindent This document presents the \pkg{RcppClassic} package. This package has been factored out of \pkg{Rcpp} \citep{CRAN:Rcpp,Eddelbuettel:2013:Rcpp, CRAN:Rcpp,PeerJ:Rcpp,TAS:Rcpp} and only contains code that is considered deprecated.

This package is released for the sole purpose of allowing package authors that are still using the classic \pkg{Rcpp} API to keep their package buildable. This document explains the changes needed in a package to use both the current and classic \pkg{Rcpp} APIs.

If you must use RcppClassic {.unnumbered}

A few changes are needed in packages that want to use the classic \pkg{Rcpp} API that is contained in \pkg{RcppClassic}. A sample package called \pkg{RcppClassicExample} is on CRAN and can be used as a template.

The DESCRIPTION file

The client package must declare that it depends on both \pkg{Rcpp} and \pkg{RcppClassic} in the Imports field and the LinkingTo field, so it must contain this:

Imports: RcppClassic, Rcpp
LinkingTo: RcppClassic, Rcpp

The NAMESPACE file

The client package should import both \pkg{Rcpp} and \pkg{RcppClassic}:

importFrom(Rcpp, evalCpp)
import(RcppClassic)

The Makevars file

The Makevars file must be updated so that user libraries for both \pkg{Rcpp} and \pkg{RcppClassic} are used. For \pkg{Rcpp} 0.11.0 we used

## This can be placed on one or two lines too
PKG_LIBS = \
  `$(R_HOME)/bin/Rscript -e \
     "Rcpp:::LdFlags()"` \
  `$(R_HOME)/bin/Rscript -e \
     "RcppClassic:::LdFlags()"`

but starting with \pkg{Rcpp} version 0.11.0, the result of \verb|Rcpp:::LdFlags()| is an empty string as Rcpp no longer provides a user-library. The above then reduces to

## This can be placed on one lines
PKG_LIBS = `$(R_HOME)/bin/Rscript -e \
   "RcppClassic:::LdFlags()"`

which finds the required RcppClassic library.

The Makevars.win files

The Makevars.win must also be updated for the same reason, and in similar way. Use ${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe instead of $(R_HOME)/bin/Rscript to reflect both the bi-architecture nature of Windows builds and the differently names Rscript executable.

Include RcppClassic.h instead of Rcpp.h

Finally, all instances of this line :

#include <Rcpp.h>

need to be replaced by:

#include <RcppClassic.h>

You should not use RcppClassic {.unnumbered}

The previous section discusses the set of changes required to update a package so that it uses the classic API from \pkg{RcppClassic} since it has been removed from \pkg{Rcpp}.

We do, however, recommend that package authors stop using the classic API. Iy has been more than superseded by the current \pkg{Rcpp} API in terms of performance, design, maintainance, and ease of use.

eddelbuettel/rcppclassic documentation built on March 3, 2024, 10:18 a.m.