Ok I see. But can you have a (anonymous or not) namespace inside of a function?

Having a constant in anonymous namespace also means we’ll allocate it only once. And one of the major disadvantage of having static variable is the thread safety provided by the standard & compiler. So, even though the data is const, compiler generates locks before that for thread safety. Although this happens mostly with the objects which requires dynamic allocation(like std::string). For rest, (like int), compiler optimisations do their job properly.
On that other hand, if its in anonymous namespace, it might be directly substituted by compiler optimisation based on flag as well and no thread locking related code is generated. And also provides us a way to maintain all the const data at the same place making it more maintainable.

Here the meaning of static means to allocate once, and not private to the file like the anonymous namespace. Do you mean that we shouldn’t allocate it once then?

Hello, so the only piece that isn’t shown in detailed implementation in the post is the consecutive adaptor. Here is the one in the range-v3 library, which is called ranges::view::sliding instead of “consecutive”: https://github.com/ericniebler/range-v3/blob/afd3c77dabdf9816ffb7e266a8d9d55b86005834/include/range/v3/view/sliding.hpp.
For the rest, all the code is included in this post unless I’m mistaken.

Thanks for the reply =)
Looking forward to the new article and the next challenge. Great blog! =)

Hi Tina,

I think you’re 100% right in that using a lambda would be more adapted than a functor here. Now this functor here has the slight advantage over a named lambda of completely hiding the implementation code from the `computeNumberOfBreaks` function.

However this can also be achieved with a bit more work on the lambda, although I guess that you got how since you seem already quite familiar with lambdas.

I may be wrong here but I think that dedicating a blog post to this particular technique on lambdas will make posts more modular, as opposed to cramming everything in this single post.

This article on lambdas is coming up on Jan 20, and I’ll be very keen on hearing your thoughts on it when you read it 🙂

And boost can be used on challenges for expressive code.

Thanks for your comment and stay tuned on Fluent C++

const auto FartherThan = (const auto& cities)[&]
{
return cities.first.getGeographicalAttributes().getLocation().distanceTo(
cities.second.getGeographicalAttributes().getLocation()) > MaxDistance;
};

Pass this on to your copy_if like you did with the functor.

And if you use boosts copy_if you won’t have to write your own version. Or is using boost not part of the challenge?

Hey Jerry,

Thanks a lot for proposing your solution to the challenge for the most expressive code.

I personally reviewed your solution. Although there could be one winner only, what I could say for sure is that your code shows that you know your stuff. You proposed a smart solution using various modern technologies, and provided interesting comments alongside. We need more people like you to share their opinions and knowledge on Fluent C++.

Indeed you’ll get more about lambdas on Jan 20th, and much more to come until then (posts are up every Tuesday and Friday) so stay tuned, and hoping to hear more from you in the next posts.

Jonathan