Re: [Interest] Flags: Non-intrusive, type-safe bitwise operators for enums

On Mon, Mar 16, 2026 at 12:00 PM Tobias Loew via Boost
<[email protected]> wrote:
> I would like to gauge interest in a library [...] which provides type-safe,
> non-intrusive bitwise operators for C++ enumerations.
> [...] I am interested in hearing if the community sees a place for this in Boost

FWIW, I rolled-up my own a while back, like many I'm sure,
so there's obviously a need, IMHO. I'd welcome a Boost quality one,
which would be, I'm sure, heads and shoulders better than mine. --DD

// Adapted (and fixed) from
// https://softwareengineering.stackexchange.com/a/338472/189774
template <typename Enum>
class BitFlags {
    static_assert(std::is_enum_v<Enum>);
    using underlying_t = typename std::underlying_type<Enum>::type;
    constexpr const static int number_of_bits =
std::numeric_limits<underlying_t>::digits;

public: ...
private:
    std::bitset<number_of_bits> bits_;
};

template <typename Enum>
constexpr std::enable_if_t<std::is_enum_v<Enum>, BitFlags<Enum>>
operator|(Enum left, Enum right) {
    return BitFlags<Enum>(left) | right;
}
template <typename Enum>
constexpr std::enable_if_t<std::is_enum_v<Enum>, BitFlags<Enum>>
operator&(Enum left, Enum right) {
    return BitFlags<Enum>(left) & right;
}
template <typename Enum>
constexpr std::enable_if_t<std::is_enum_v<Enum>, BitFlags<Enum>>
operator^(Enum left, Enum right) {
    return BitFlags<Enum>(left) ^ right;
}
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