Support inherited classes with reflection

[decades42]

First of all, thank you for this awesome library, I've been trying to migrate my old projects with this library and most of them work flawlessly. However the library doesn't support inherited classes with reflection on, although I can disable reflection on them and use macros instead, it would be tedious to type when there are too many fields in the class

[stephenberry]

Right now reflection only works on aggregate initializable structs, which rules out inheritance. This is a limitation you will see for any library currently implementing pure reflection, until we get C++26 reflection. There may be a work around this limitation, but currently I would recommend using macros or glz::meta. Thankfully the glz::meta definitions will now reflect on your member pointer names, so that saves typing.

[schaumb]

Hi @stephenberry !
This isn't true (only at boost pfr, because I didn't have time to make it work with the empty structs with multiple inheritances ).
You can implement it with the same technique that I did here.

[stephenberry]

I understand that you may be able to get names from inherited non-aggregate structs, but can you use this loophole to get pointers?

[schaumb]

Yes of course. The loophole technique is way more powerful than structure binding. Currently, it is only used for aggregate initializable member type-getters (and information leaking hacks like this).
There are unused features like recognize template-constructor or get list of the aggregates base classes
After that, you can select which were the base classes, and you can cast the main object to it.

[scalpel4k]

is this something that could make it back into the open issue list?

[stephenberry]

@scalpel4k, I'm open to pull requests that add inheritance support, but I'm a bit leery of implementing it in C++20. Reflection is coming in C++26 and will make any code written to support this obsolete. There are a lot of higher priorities for the library right now, which include handling streams, networking, modules, and better runtime/compile-time performance.