Re: [boost] Interest in updated, standalone iterator_facade library?

Dear Zach, Dear Zach,

On 11. Aug 2019, at 18:00, Zach Laine via Boost wrote:

On Sun, Aug 11, 2019 at 10:52 AM Peter Dimov via Boost < boost@lists.boost.org> wrote:

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Zach Laine wrote:

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On Sun, Aug 11, 2019 at 5:43 AM Peter Dimov via Boost wrote:

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Zach Laine wrote:

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https://tzlaine.github.io/iterator_facade

`reference` being `char const` in the introductory example doesn't feel correct. `char const` can't be returned from a function (such as `operator*`), top-level qualifiers aren't meaningful for `char`.

It is correct, as of C++20. Proxy iterators are first-class citizens, as of the ranges concepts work. I used that reference type on purpose, and I refer to that later in the docs. Also, this is copy-paste from Boost.Text (proposed), which uses that exact iterator with a "char const" reference type.

Thanks. You should however be aware that both gcc and clang warn on functions returning `const char` with -Wextra. :-)

Huh. Good to know. I guess I should change it to char then.

+1 for the proposal to have a modern iterator_fascade. I use a private implementation of iterator_fascade in Boost.Histogram for a couple of reasons, but mostly because the old boost iterator library pulls in a lot of boost dependencies which I want to avoid. But code duplication is bad, so I am looking forward to switch to your library which only depends on the stdlib. I object to change the name of iterator_fascade. The established convention in Boost is to call a updated library X with the same purpose X2, see variant and variant2, coroutine and coroutine2, signal and signal2, etc. This library should follow this route and be called iterator2. I am by no means an expert of the iterator_fascade, but I spend some time to figure out how the old iterator_fascade works, and it has some subtle solutions to corner case situations. Therefore, I would recommended that you port the iterator test suite to your project (if you haven't done so already). Also, please add a modern iterator_adaptor. iterator_adaptors are awesome, because you need to implemented even less. Best regards, Hans