Robert Jones wrote:
A recent post in this list started me thinking...
Given this code snippet,
using namespace std;
void f( int, int );
vector<int> v1; vector<int> v2;
// populate...
for ( unsigned i = 0; i <= v1.size( ); ++ i ) { f( v1[ i ], v2[ i ] ); }
How would you write this as a for_each() or in some other Boosty, functional way? (The aspect I'm trying to highlight is that two iterators over different ranges must advance in step)
One could imagine a tuple-based solution, in which one specifies how an operation applied to the tuple distributes to operations applied to each of the tuple's elements.
Does any such thing exist in Boost? Is it ever necessary, or can the functionality be achieved by some C++/STL/Boost idiom that I've not thought of?
If there is no obvious technique, is there any interest in a Boost library which address this in a generic way?
Thanks.
- Rob.
The tuple-based solution seems elegant if you have a varying number of ranges. For your two ranges requirement, a simple custom writing of a for_each would do, like this: template<class ForwardIterator, class ForwardIterator2, Class Op> Op for_each(ForwardIterator first, ForwardIterator last, ForwardIterator2 first2, Op op){ for(;first != last; ++first, ++first2) op(*(first), *(first2)); return (op); } Does this work for you?