On 12/07/12 09:15, tolik levchik wrote:
Why min_element give me errors without BOOST_RANGE_ENABLE_CONCEPT_ASSERT defined 0? Is it uses only for makeerror messages more readable? Is it safe to define it to 0?
Firstly, it is definitely safe to consistently define BOOST_RANGE_ENABLE_CONCEPT_ASSERT as 0. This will disable concept checking within Boost.Range. The intent of the concept checking is two-fold. It will detect usage errors at compile-time that in some cases may become run-time errors without the checks. It also provides better error messages close to the location of the error.
#include <vector> //#define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 #include
#include #include #include #include struct foo{ int x; };
int main() { using namespace boost::adaptors; using boost::bind;
std::vector<foo> vec; auto rng = vec | transformed(bind(&foo::x, _1)); boost::accumulate(rng, 0); // ok boost::min_element(rng); // error }
I suspect that the underlying transform_iterator alters the return type of the dereference operator that technically demotes the iterator category. If this is the case then this is a defect in the Boost.Range library that I shall need to address. I should have used the Boost iterator traversal categories. I shall look into this. Thank you for the report. Regards, Neil Groves