Every obejct will initialize twice?

[qinwf]

Hi Rich, I just try to put RcppR6 into my own packages. This package is really inseresting!

Reading the code of RcppR6, I just learned how to use XPtr in Rcpp. oops... I missed this feature when I first read Dirk's book.

I found that RcppR6 can really speed up the loading process, and the size of package will be smaller too.

I also found that the time of initializing a new obejct was twice as much as the Modules based package, if it takes more than 1s to create a raw C++ obejct.

After reading the source code, I found that RcppR6 will initialize every obejct twice before the obejct is exported into R. If it will take a great time to initialize a raw C++ obejct, RcppR6 will be slower than Rcpp Modules, and maybe will take more internal storage too.

namespace Rcpp {
template <typename T>
SEXP wrap(const jiebaR6::RcppR6::RcppR6<T>& x) {
  return x.to_R6();
}

template <> inline SEXP wrap(const jiebaR::mixseg& x) {
  return wrap(jiebaR6::RcppR6::RcppR6<jiebaR::mixseg>(x));
}

////  mixseg is the class needed to be exported into R, and will take 2s to create in pure C++ code.

And the classes in C++ which I wanted to be exported into R are inherited from a class which has a private copy constructor. So if I want to use RcppR6, I need to construct a copy constructor for this class, It seems that the class must have a copy constructor if it need to be exported by RcppR6. If I use Rcpp Modules, I do not need to worry about this.

As soon as I learned XPtr, I knew a much easier way to export C++ class even without the help of R6.

Thanks.

[richfitz]

Thanks for finding that out - this is very useful, and clearly a design problem. I'll think about how to fix this.

RcppR6 came from using XPtr (which is lovely) but you can't do much with pointers in R without providing a bunch of boilerplate - RcppR6 aims to do that boilerplate for you.

I plan on doing a lot of work with RcppR6 in the new year and will fix this then.

[richfitz]

OK, this, p7 explains what is going on with the current version. Using an equivalent of make_shared would help, but I don't think that there is an XPtr equivalent, and writing one is probably beyond me at the moment.

I'd wondered about going through shared_ptr, but it looks like that won't work: http://stackoverflow.com/a/26220868