register.md
In cpp4r: Header-Only 'C++' and 'R' Interface

get_call_entries / returns an empty string for packages with .Call entries and NAMESPACE files

Code
  call_entries
Output
  [1] "/* .Call calls */"                             
  [2] "extern SEXP bar(void);"                        
  [3] ""                                              
  [4] "static const R_CallMethodDef CallEntries[] = {"
  [5] "    {\"bar\", (DL_FUNC) &bar, 0},"             
  [6] "    {NULL, NULL, 0}"                           
  [7] "};"

get_call_entries / works with multiple register functions.

Code
  cat(read_file(cpp_bindings))
Output
  // Generated by cpp4r: do not edit by hand
  // clang-format off


  #include "cpp4r/declarations.hpp"
  #include <R_ext/Visibility.h>

  // multiple.cpp
  int foo();
  extern "C" SEXP _testPkg_foo() {
    BEGIN_CPP4R
      return cpp4r::as_sexp(foo());
    END_CPP4R
  }
  // multiple.cpp
  double bar(bool run);
  extern "C" SEXP _testPkg_bar(SEXP run) {
    BEGIN_CPP4R
      return cpp4r::as_sexp(bar(cpp4r::as_cpp<cpp4r::decay_t<bool>>(run)));
    END_CPP4R
  }
  // multiple.cpp
  bool baz(bool run, int value);
  extern "C" SEXP _testPkg_baz(SEXP run, SEXP value) {
    BEGIN_CPP4R
      return cpp4r::as_sexp(baz(cpp4r::as_cpp<cpp4r::decay_t<bool>>(run), cpp4r::as_cpp<cpp4r::decay_t<int>>(value)));
    END_CPP4R
  }

  extern "C" {
  static const R_CallMethodDef CallEntries[] = {
      {"_testPkg_bar", (DL_FUNC) &_testPkg_bar, 1},
      {"_testPkg_baz", (DL_FUNC) &_testPkg_baz, 2},
      {"_testPkg_foo", (DL_FUNC) &_testPkg_foo, 0},
      {NULL, NULL, 0}
  };
  }

  extern "C" attribute_visible void R_init_testPkg(DllInfo* dll){
    R_registerRoutines(dll, NULL, CallEntries, NULL, NULL);
    R_useDynamicSymbols(dll, FALSE);
    R_forceSymbols(dll, TRUE);
  }

register / works with a package that registers a single c++ function

Code
  cat(read_file(r_bindings))
Output
  # Generated by cpp4r: do not edit by hand

  foo <- function() {
    .Call(`_testPkg_foo`)
  }

Code
  cat(read_file(cpp_bindings))
Output
  // Generated by cpp4r: do not edit by hand
  // clang-format off


  #include "cpp4r/declarations.hpp"
  #include <R_ext/Visibility.h>

  // single.cpp
  int foo();
  extern "C" SEXP _testPkg_foo() {
    BEGIN_CPP4R
      return cpp4r::as_sexp(foo());
    END_CPP4R
  }

  extern "C" {
  static const R_CallMethodDef CallEntries[] = {
      {"_testPkg_foo", (DL_FUNC) &_testPkg_foo, 0},
      {NULL, NULL, 0}
  };
  }

  extern "C" attribute_visible void R_init_testPkg(DllInfo* dll){
    R_registerRoutines(dll, NULL, CallEntries, NULL, NULL);
    R_useDynamicSymbols(dll, FALSE);
    R_forceSymbols(dll, TRUE);
  }

register / can be run with messages

Code
  register(p, quiet = FALSE)
Message
  i 1 functions decorated with [[cpp4r::register]]
   Generated file 'cpp4r.R'
   Generated file 'cpp4r.cpp'