Re: Access to enum definition at run time

Glad to hear !

While C might never have full introspection or reflection as a
"built-in" feature - a lot of benefits can be derived for exposing
light-weight "reflection-like" data to reduce boilerplate code.

Yair

On Thu, Apr 30, 2026 at 8:35 PM Martin Uecker <[email protected]> wrote:
>
> Am Donnerstag, dem 30.04.2026 um 16:14 +0200 schrieb Jakub Jelinek via Gcc:
> > On Thu, Apr 30, 2026 at 04:54:02PM +0300, Yair Lenga wrote:
> > > Thanks for taking the time.
> > > My focus is on the C compiler. Assuming the enum "metadata" is stored
> > > in a structure/variables that are readable by the program - can C
> > > programs access it ? Does it apply to "C" enums, or only to "C++" enum
> > > classes.
> >
> > Any kind of enum.
> > It is roughly
> > #include <meta>
> >
> > template <typename E>
> > constexpr const char *
> > enum_to_string (E v)
> > {
> >   template for (constexpr auto e : std::define_static_array (enumerators_of (^^E)))
> >     if (v == [:e:])
> >       return std::define_static_string (identifier_of (e));
> >   return nullptr;
> > }
> >
> > example of how it can be used:
> > enum E { F, G, H } i;
> >
> > int
> > main ()
> > {
> >   const char *f = enum_to_string (F);
> >   const char *g = enum_to_string (G);
> >   const char *h = enum_to_string (H);
> >   const char *j = enum_to_string (i);
> > }
> > Of course, if compiled with C++26 for use in C, one would need to
> > wrap it in a wrapper, one per enum so that C can use it.
> > Also, note the above function when not evaluated at compile time doesn't
> > have a switch but a series of ifs, but e.g. GCC when optimizing ought to
> > transform that into a switch and later perhaps into an array access or
> > whatever is appropriate based on how dense the enumerals in the enumeration
> > type are, how many etc.
> >
> >       Jakub
>
> BTW: I often felt the need for a type-to-string serialization
> builtin in C. This would be incredible useful for many things.
>
>
> Martin
>
>
>
>