[skribanto]

Maybe have your public fields defined as a second struct, and then you can cast the pointer to your struct to the concrete struct that has all the public fields. This has the restriction that all public fields must be at the start, and you must make sure to maintain the same order between the two structs.

At this point though, I think I honestly would prefer setters/getters.

    struct MyClassPublic {
        int x;
        int y;
        ...
    }

    /* using it */
    MyClass *myclass = myclass_create();
    ((MyClassPublic *)myclass)->x = 5;