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

On Tue, 17 Mar 2026 at 06:38, Julien Blanc via Boost <[email protected]>
wrote:

> I've come to the conclusion that any representation of enum flags with
> C++ enums is a design mistake by itself (a pretty widespread one, but
> still a mistake). Enums are individual values, enum flags are a set of
> values, they are different by nature. In C++, different things deserve
> a different type, call it an enum_bitset, an enum_set or whatever, but
> donc make it a plain enum / enum class.


I totally agree. We’ve had this same discussion in November and I’ve made
the same argument. Conceptually, enum values and sets of enum values should
be different things. C code has always made the distinction between enums
(`enum`) and enum sets (`unsigned int`).

The only hurdles here are practical in nature. C++ technically treats any
bit pattern of an enum type as a valid value, so you could argue there is
no need for a second type. Furthermore, there is no standard “enum set”
type, so you have to invent one yourself, which is kind of a big deal for
something so fundamental, especially in public interfaces.

-Janko

>
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