struct class {
    int a;
    int (*method)(struct class* this, int b, int c);
};

int code(struct class* this, int b, int c) {
    return this->a*b+c;
}

struct class constructor(int a) {
    struct class result = {a, code};
    return result;
}

#define call(obj, method, ...) ((obj).method(&(obj), __VA_ARGS__))

#include <stdio.h>
int main() {
    struct class obj = constructor(10);
    int result = call(obj, method, 2, 3);
    printf("%d\n", result);
    return 0;
}