Hi,
That’s because VTYPE::value_type is traits::r_vector_proxy<RTYPE>::type, i.e.
template <int RTYPE>
struct r_vector_proxy{
typedef typename storage_type<RTYPE>::type& type ;
} ;
so VTYPE::value_type is int&
You can either use stored_type, i.e.
std::for_each( v.begin(), v.end(),[]( const VTYPE::stored_type& ) ...
Or do a little dance with the reference qualifier:
std::for_each( v.begin(), v.end(),[]( const
std::remove_reference<VTYPE::value_type&>::type& __n ) ...
Both of which are not very satisfying.
FWIW, in Rcpp11/Rcpp14, VTYPE::value_type is defined like this:
typedef typename traits::storage_type<RTYPE>::type value_type ;
so IntegerVector::value_type is int, and therefore you get what you rightfully
expect.
Romain
> Le 31 mars 2015 à 00:19, Kevin Thornton <krtho...@uci.edu> a écrit :
>
> Hi,
>
> I've come across an issue when compiling some code with Rcpp >= 0.11.4 (using
> R 3.1.3 with either gcc or clang on Linux, or clang on OS X).
>
> The code that reproduces the issue is here:
> https://gist.github.com/molpopgen/b3bda09590172044ff84
>
> Specifically, the last function is where I'm running into trouble. I also
> tried the same ideas using C++98 (function objects instead of lambda
> expressions), and got the same results.
>
> The short version is that Rcpp::IntegerVector::value_type appears to lose
> some info about value_type's const-ness when a const IntegerVector is passed
> to an Rcpp function. I went back an tried older version of Rcpp and verified
> that the code from the above link compiles with version from 0.11.0 through
> 0.11.3. Starting with 0.11.4, the last function in that piece of code will
> no longer compile, and appears to think that a non-const int & is the type
> that it is looking for.
>
> I tried the other STL-like typedefs that one may expect ( reference,
> const_reference ), and they do not exist for Rcpp vector types.
>
> Any thoughts? Is this intended? Should I not write functions taking const
> references to Rcpp types?
>
> Best,
>
> Kevin
>
> ___________________________
> Kevin Thornton
> Associate Professor
> Ecology and Evolutionary Biology
> University of California, Irvine
> http://www.molpopgen.org
> http://github.com/molpopgen
> http://github.com/ThorntonLab
>
>
>
>
>
>
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