I paraphrase Mateusz Pusz from one of his courses: prefer free functions
over member functions.
ADL is a thing in C++ and I see no benefits of this proposal vs to utilize
ADL and just define a free "to_string"-method in the enclosing namespace.
Free functions found with ADL are just as much part of a types API as their
member functions.

// Robin

On Wed, Mar 12, 2025, 06:47 Simon Schröder via Std-Proposals <
std-proposals_at_[hidden]> wrote:

>
>
> > On Mar 12, 2025, at 2:23 AM, Dmitrii Shabalin via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
> >
> > If you have any idea how to have a function inside in the enum, please,
> share your idea with an example.
>
> My first thought was that instead of allowing enums to have member
> functions I would put an enum inside a class:
>
> class Test
> {
> public:
> // not en enum class on purpose!
> enum TestEnum { test_value = 0 };
>
> static string_view to_string(TestEnum);
> }
>
> Declaring a variable is slightly more to type:
> Test::TestEnum e = test_value;
> and you can‘t call it as a member function:
> e.to_string(); // not possible
>
> However, the “member function call” could be solved differently. We could,
> once more, try to allow for member call syntax to also look for “free
> standing” (or otherwise scoped functions) that take the type as the first
> parameter. (With this solution it doesn’t really matter if we put the enum
> inside a namespace or class.)
> --
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>