I agree with your complaints about the article, but the code example you give could be demonstrating programming with abstract data types in C just as well as i

I agree with your complaints about the article, but the code example you give could be demonstrating programming with abstract data types in C just as well as it could be demonstrating programming with objects. In fact, unless frobnicate_foo is just a convenience function to look up a frobnicate function pointer in the foo_t structure and invoke it, I'd have to say that you're clearly demonstrating an ADT here.