[Development] Changed enum property behaviour in Qt v6.8

[Phil Thompson]

Thanks - that was extremely helpful.

On 05/10/2024 01:50, Thiago Macieira wrote:
> On Friday 4 October 2024 07:42:39 GMT-7 Phil Thompson via Development 
> wrote:
>> Understood - but there seems to be no obvious way to dynamically 
>> create
>> and register a valid QMetaType.
> 
> What do you mean by a dynamic meta type? Are you trying to wrap some 
> other
> language? Because if the type exists in C++, it exists as a metatype.
> 
> If you're trying to wrap, then create a QtPrivate::QMetaTypeInterface 
> and fill
> it in appropriately. See https://qt.godbolt.org/z/5EW14qz3Y for an 
> example of
> the metatype for an enum and https://qt.godbolt.org/z/67PPfecdE for a 
> Q_ENUM.
> Most of the fields are self-explanatory, but here's a decode:
> 
> * flags = RelocatableType | IsEnumeration, maybe isUnsignedEnumeration
> * typeId = must be set to zero by you and QMetaType will update with 
> the ID
> * metaObjectFn = you should fill in
> * name = must be present and must be unique
> * default, copy, moveCtr, dtor  = nullptr for trivial types
> * equals, lessThan = optional but probably a good idea for enums
> * debugStream = optional (huh, QMT is failing to extract for enums
> * datastreams = optional but recommended
> * legacyRegisterOp = nullptr for enums is fine
> 
> Each of the callback functions is called with a pointer to the QMTI in
> question so you can return different things where needed (the meta 
> object, in
> particular). One trick is to create your type deriving from 
> QMetaTypeInterface
> and add the information you need in your own members after that; in 
> your
> callbacks, static_cast the pointer that was passed to your type to 
> access the
> extra fields.