Hi, Thanks, Inaki, Dirk, and Matthew for the replies to my query. Thank you Matthew for your code samples, they were very helpful in finding my way through the problem.
I am trying to wrap some code from a library, though the code base is rather large so I didn't want to paste that into the rcpp-devel mailing list. I have uploaded a sample code to Git Hub. You can see it here ( https://github.com/nikhil003/testSingleton). It is pretty much what Matthew had written down with slight modifications to reflect my particular case. Hope this gives some idea of how I imagine it should work. I am very new to Rcpp but I will be spending some time learning it so that I can have a working knowledge of it. Any suggestions or guidance is highly appreciated. Regards, Nikhil On Thu, 22 Feb 2024 at 06:18, Matthew Supernaw - NOAA Federal < matthew.super...@noaa.gov> wrote: > Hi Nikhil, > > Here's an updated version that exposes a FooWrapper class in the module to > the previous posted code. Hopefully this helps! > > class FooWrapper{ > public: > Foo* foo_m; > FooWrapper(){} > > > FooWrapper(const FooWrapper& other):foo_m(other.foo_m){ > > } > > FooWrapper(Foo* foo):foo_m(foo){ > > } > > void SayHello(){ > Rcpp::Rcout << "From \"void SayHello()\" -> "<<(this->foo_m)<<" -> "; > Rcpp::Rcout << "hello from Foo.\n"; > } > > }; > > > > RCPP_EXPOSED_CLASS(FooWrapper) > > FooWrapper GetSingleton(){ > FooWrapper ret(Foo::GetSingleton()); > Rcpp::Rcout<<"From \"Foo& GetSingleton()\" -> memory address for > singleton is " <<ret.foo_m<<"\n"; > return ret; > } > > > > > > RCPP_MODULE(foo) { > Rcpp::class_<FooWrapper>("Foo") > .constructor() > .method("SayHello", &FooWrapper::SayHello); > Rcpp::function("GetSingleton", &GetSingleton); > > } > > On Wed, Feb 21, 2024 at 10:51 AM Matthew Supernaw - NOAA Federal < > matthew.super...@noaa.gov> wrote: > >> Looks like I posted too soon. I just noticed the memory address from the >> "SayHello" function doesn't match. >> >> On Wed, Feb 21, 2024 at 10:47 AM Matthew Supernaw - NOAA Federal < >> matthew.super...@noaa.gov> wrote: >> >>> Hi Nikhil, >>> I'm not exactly sure what you are trying to do, but I hope this simple >>> example is helpful. >>> Thanks. >>> Matthew >>> >>> >>> #include <Rcpp.h> >>> using namespace Rcpp; >>> >>> >>> class Foo{ >>> public: >>> static Foo* singleton; >>> >>> Foo(){ >>> } >>> >>> void SayHello(){ >>> Rcpp::Rcout << "From \"void SayHello()\" -> "<<this<<" -> "; >>> Rcpp::Rcout << "hello from Foo.\n"; >>> } >>> >>> static Foo* GetSingleton(){ >>> >>> if(singleton == NULL){ >>> Foo::singleton = new Foo(); >>> } >>> Rcpp::Rcout<<"From \"static Foo* GetSingleton()\" -> memory address >>> for singleton is " <<Foo::singleton<<"\n"; >>> return Foo::singleton; >>> } >>> }; >>> >>> Foo* Foo::singleton = NULL; >>> >>> RCPP_EXPOSED_CLASS(Foo) >>> >>> Foo& GetSingleton(){ >>> Foo* foo_singleton = Foo::GetSingleton(); >>> Rcpp::Rcout<<"From \"Foo& GetSingleton()\" -> memory address for >>> singleton is " <<foo_singleton<<"\n"; >>> return *foo_singleton; >>> } >>> >>> RCPP_MODULE(foo) { >>> Rcpp::class_<Foo>("Foo") >>> .constructor() >>> .method("SayHello", &Foo::SayHello); >>> Rcpp::function("GetSingleton", &GetSingleton); >>> >>> } >>> //From R >>> // library(singleton) >>> // library(Rcpp) >>> // >>> // foo <- Rcpp::Module("foo", PACKAGE = "singleton") >>> // >>> // foo_singleton<-foo$GetSingleton() >>> // foo_singleton$SayHello() >>> >>> // Output: >>> // From "static Foo* GetSingleton()" -> memory address for singleton is >>> 0x7fcdf9387590 >>> // From "Foo& GetSingleton()" -> memory address for singleton is >>> 0x7fcdf9387590 >>> // From "void SayHello()" -> 0x7fcdf9392b60 -> hello from Foo. >>> >>> On Wed, Feb 21, 2024 at 1:34 AM Nikhil Garg <nikhilgarg....@gmail.com> >>> wrote: >>> >>>> Hi, >>>> >>>> I am looking for some advice or hoping someone can point me in the >>>> right direction for wrapping a C++ class with singleton using Rcpp. I have >>>> been using RCPP modules for some of this work but got stuck with a C++ >>>> object which returns a singleton. >>>> >>>> Here is the general structure of the object >>>> >>>> class Foo { >>>> public: >>>> Foo(); >>>> ~Foo(); >>>> >>>> static Foo &getFoo(); >>>> Foo(Foo const&) = delete; >>>> void operator=(Foo const&) = delete; >>>> } >>>> >>>> Regards, >>>> Nikhil >>>> _______________________________________________ >>>> Rcpp-devel mailing list >>>> Rcpp-devel@lists.r-forge.r-project.org >>>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel >>>> >>> >>> >>> -- >>> Matthew Supernaw >>> *Scientific Software Developer* >>> *National Oceanic and Atmospheric Administration* >>> *Office Of Science and Technology* >>> *NOAA Fisheries | *U.S. Department of Commerce >>> Phone 248 - 396 - 7797 >>> >>> >>> >> >> -- >> Matthew Supernaw >> *Scientific Software Developer* >> *National Oceanic and Atmospheric Administration* >> *Office Of Science and Technology* >> *NOAA Fisheries | *U.S. Department of Commerce >> Phone 248 - 396 - 7797 >> >> >> > > -- > Matthew Supernaw > *Scientific Software Developer* > *National Oceanic and Atmospheric Administration* > *Office Of Science and Technology* > *NOAA Fisheries | *U.S. Department of Commerce > Phone 248 - 396 - 7797 > >
_______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
