On 12-11-2013 16:41, Eric Niebler wrote:
I've now built a filter_range, transform_range, and an istream_range in this vein. Initial results are looking promising, but I haven't benchmarked performance, yet. A commenter on my blog claims to have benchmarked perf of istream_range, with good results, which is encouraging.
If anybody wants to take a peek, you can find the code here:
https://github.com/ericniebler/range-v3
I'm making no effort to maintain source compatibility, going instead with the design that seems right to me for C++11.
Good. I totally agree that r-value refs change things completely. Some small comments (applies for transform_range as well): A. For filter_range, you should inherit from the predicate if possible to enable EBO. I don't know if lambdas complicate this? B. For the constructor filter_range(Rng && rng, Pred pred) then maybe it would be beneficial that empty predicates are constructed via filter_range(Rng && rng) ? I guess it needs benchmarking though, but the compiler will have to elide a series of moves vs. default construct an empty class. C. I can't quite figure out your use of filterer::filterer1. Do you really have to store the predicate here also? -Thorsten