Probably just my incompetence at the time of writing it.
Would be trivial enough to fix in Rcpp for anyone with the proper skills and
willingness. I only have 1.05 of those 2.
Romain
> Le 31 mars 2015 à 17:39, Kevin Thornton <krtho...@uci.edu> a écrit :
>
> Thanks for the explanation, Romain.
>
> As a follow-up, is there a reason why value_type is defined in terms of a
> reference? In the mean time, I'll use remove_reference.
>
> -Kevin
>
>
>> On Mar 31, 2015, at 1:04 AM, Romain François <rom...@r-enthusiasts.com>
>> wrote:
>>
>> 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
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> 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
>>
>
> ___________________________
> 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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