Re: [Boost-users] [iterators][range][rangeex] range concatenation

7 Apr 2009

      Neil Groves skrev:
...
On Mon, Apr 6, 2009 at 10:46 PM, Thorsten Ottosen 
mailto:thorsten.ottosen@dezide.com> wrote:
Dmitry Vinogradov skrev:
Calling process_range() twice is not a solution in my case.
        Copying references to a new container is a better way.
Regarding efficiency, can you look thru my rough concat()
        implementation attached to discover any its disadvantages?
It is undeniably more elegant than calling algorithms n times as a 
general solution. It is possible to improve performance by reordering 
some of the boolean expressions and by reducing the use of boost variant.
Right on.
...
If the performance is good,this baby should be included in the range
    library asap.
I would like to implement a new version of this functionality, since I 
have some code I had prototyped previously. I believe that the idea is 
good, but the functionality should efficiently support two random access 
iterators, and that the performance can be improved by reducing the use 
of boost::variant, although I would have to measure the variant approach 
to be certain. I can add this to the list of things to do in response to 
the Boost.RangeEx review.
Great. I'm *sure* that the variant thing adds overhead:

1. when the iterators have different size

2. because we check two times that we have a certain case:

   if( range == 0 )

also implies that we should increment a certain iterator, else another.

I wonder if we could call this beast

    join_view(r1,r2)

or something. Perhaps support for 3 and 4 ranges would be nice.

-Thorsten