on Wed Oct 05 2011, Marshall Clow <mclow.lists-AT-gmail.com> wrote:
So, what do people prefer (and why?):
template<typename InputIterator, typename V> bool none_of_equal ( InputIterator first, InputIterator last, V const &val ) { for ( ; first != last; ++first ) if ( val == *first ) return false; return true; }
or
template<typename InputIterator, > bool none_of_equal ( InputIterator first, InputIterator last, iterator_traits<InputIterator>::value_type const &val ) { for ( ; first != last; ++first ) if ( val == *first ) return false; return true; }
In the first case, I think there's (possible) conversion from V to iterator_traits<InputIterator>::value_type each time through the loop. In the second case, there is not.
I prefer the second one. - It's the one that matches the mental model: I don't know what the first algorithm /means/. - An exact specification for the first one is more complicated - It's more efficient in the usual case when a conversion would be needed
Of course, the (mythical?) smart compiler would do the conversion once and save the result for reuse.
I think you know the compiler would have to be able to verify that the conversion had no side-effects; not something we're likely to see for some time. -- Dave Abrahams BoostPro Computing http://www.boostpro.com