> A long long time ago, SOM, IBM’s answer to Microsoft’s COM, did this in C with alloca instead of VLAs, but that’s the same thing.

Was kind of the other way around, given the whole OS/2 versus Windows history, and that COM started as the evolution of OLE and VBX technologies, Windows 9X and Windows NT weren't as COM heavy as OS/2 was with SOM.

There was no COM to worry about on Windows 3.x back in 1991.

https://www.edm2.com/index.php/SOM_%26_DSOM_-_An_Introductio...

Also SOM was so much better, bettwen C++, Smalltalk and C, with support for meta-classes and proper inheritance implementation across such disparate languages.