[1718627440]

> like instantiation with unimplemented functions

I think this is more of an effect of C distinguishing between allocating memory (aka object creation) and initialization, which other languages disallow for other reasons, not because there are not OOPy enough.

[ryao]

Unlike OOLs, C does not enforce contracts around structures (objects). You are free to do literally anything you want to them.

[pjmlp]

Including implementing Abstract Data Types, thus everything on the structs is only accessible via functions that enforce the contracts.