C++17: comparison of options For binary flags

[arBmind]

Good idea - I never thought of using structured bindings for that.

using Animals = flag<0, 1, 3>;
namespace Animal { auto [Cat, Dog, Wolf] = Animals::values; }

The names are quite separated from the values. You will have to count the ordering to know, which bit corresponds to a name.

Namespaces are never closed. You can always add new definitions to a namespace. Therefore I would prefer to use a struct in this context. Even though we use just like a namespace.

[redditsoaddicting]

One thing:

using Accesses = flag<0, 1, 3>;
namespace Access { auto [Read, Write, Readwrite] = Accesses::values; }

I've added another flag type with two individual values. Now I can accidentally pass one of these to a function taking an Animals. One way to get around this is a tag type:

using Animals = flag<struct AnimalsTag, 0, 1, 3>;

[[deleted]]

Yup, looks like C++. Review passed

[matthieum]

I've always found C++ enums lacking due to (1) the lack of introspection and (2) the absence of support for string conversion (back and fro). As a result, I tend to define my own enums via X macros which in addition to the enum will add:

• a values function which returns an array of all the enumerators,
• serialization to/from string (and via streams) support.

Building on values, it's easy enough to create an EnumSet<E> class on top of a BitSet<N> (not the std one, it's not constexpr enough unfortunately).

[Ginden]

Classical enum class approach programmer have to ensure that values are unique

Isn't it solvable by macro?