Re: (Boost) Reflecto

Am 06.04.26 um 17:07 schrieb Emil Dotchevski via Boost:
> On Mon, Apr 6, 2026 at 6:42 AM Andrey Semashev via Boost <
> [email protected]> wrote:
>
>> Why are the enum_lookup_range limits necessary? As far as I could tell
>> from my brief glance at the code, you simply cut the enum value names
>> from function signature strings, no actual lookup is involved, so why
>> the limits?
>>
> - enum_value_name() can be invoked with a variable at run-time. This is
> implemented in terms of indexing a constexpr array constructed over the
> lookup range at compile time. If the value is out of the lookup range,
> that's indicated in the state of the returned name object.
>
> - enum_value_names<E> returns a constexpr array of name/value pairs (like
> Describe does for described enums) that includes only the named values;
> there is also named_enum_value_count and min_/max_named_enum_value.
That sounds like a heavy footgun: You can always get the name of an 
enumerator / all enumerators , except when you cannot.
For name<->enumerator conversions you could throw/static_assert to 
detect this case.
For try-to-name like functions you cannot.
And lists of enumerator names will just be incomplete.

This is amplified by this being a define 
(BOOST_REFLECTO_DEFAULT_ENUM_MIN_VALUE):
When someone (e.g. a consumer of your library built on reflecto) has 
already included reflecto and/or defined those then your code will 
suddenly break and/or have UB.

At least you can specialize a trait for "your" enums, but it's in the 
boost::reflecto namespace so requires including that header first which 
is intrusive.
Speaking of it: I'd suggest to allow specifying the first and last 
enumerators there, not (only) integers. Similar 
`static_cast<int>(EnumValue)` could be problematic.

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