Re: [boost] [Better Enums] More complete release - feedback requested

Thanks for the reply :)

On Jun 11, 2015, at 09:46, Thorsten Ottosen wrote:

On 11-06-2015 15:47, Anton Bachin wrote:

...

...

...

[snip]

...

B. make size a constexpr function

+1

I think you should look to the future and give pay-off to people using more modern C++. However you can macro-ize the constexpr keyword so that it is constexpr is supported or nothing if not.

BOOST_NO_CXX11_CONSTEXPR will do the check for you.

I’ve already done this, and I use it throughout enum.h. It’s not a problem to make a size() function constexpr only when supported, I am just not so comfortable throwing away size as an integral constant for non-C++11 users. Perhaps I can make size() a function and provide an alternative constant with an ugly name for those who might need it? Do people still use C++03? And, again, what is the rationale for size being a function?

It's more generic if you want to view the class as a container with size() and begin()/end().

Better Enums is not the container, however. It’s a class that provides access to two containers, currently through _names() and _values(). Those containers do have size() (a function), and begin()/end(): http://aantron.github.io/better-enums/ApiReference.html#Typedef_value_iterab... http://aantron.github.io/better-enums/ApiReference.html#Typedef_name_iterabl... These are containers in the sense you mean, compatible with STL algorithms, for-each loops, etc. I do value having size be a function for uniformity, so that it’s not surprising that it’s a function in the containers, yet a constant in the enum. I’m leaning towards your suggestion, and providing a constant with an alternative name for C++03 metaprogramming.

Yes, people still used C++03, but I'm sure they can live with a non-constexpr size() that is every bit as fast at runtime as a constexpr one.

Well, the issue isn’t runtime performance, it’s that you can’t use the function for some purposes before C++11. For example, only the first one works: const int size = 3; char *descriptions[size]; int size() { return 3; } char *descriptions[size()]; I may be somehow wrong with this usage example. If so, please correct me. Regards, Anton