I'd had a blast of Res0gun and DRIVECLUB earlier but TV was dull so I started poking around some trivial C struct-based object system but then realised how much i'd forgotten since GObject and CamelObject. And then realised all the boilerplate that would be needed to even use such a one, so I went back to my RKRM: Libraries and looked into cloning BOOPSI instead. The only boilerplate that needs is setting a dispatch method, although the dispatch method itself ends up being fat as it fulfills the role a vtable would.
BOOPSI (basic object oriented programming system for intuition) was the AmigaOS 2 solution to general 'objects in C' which was apparently based on SmallTalk (Amiga libraries and devices are also object oriented but are not as general). Everything is implemented using a programmed dispatch call stack rather than vtables. It's not particularly fast but it is very small and flexible and it does have one rather interesting benefit not found in C or C++ - the ability to change any object in the hierarchy without a full recompile whilst still retaining single-instance memory blocks.
The short story: I got a couple of hundred lines into the code which is enough to instantiate objects and define classes together with some core support utilities.
Will I keep poking? I'm slightly curious perhaps but not quite curious enough for that as it gets involved very quickly. Maybe if I use GLX instead of the raw X I was thinking of (BOOPSOGL?). OpenVG? Text rendering is the biggest hassle either way. And layouts, although i've looked at that before.
I guess at least one observation is that back then this stuff looked so fat and cumbersome (albeit a large improvement over base intuition or gadtools), but then yeah, i've seen what else has come since and it really really wasn't.