#include<stdio.h>

typedef struct {
    int (*data)[3];
    int (*method[5])();
} obj;

int sum (obj *this) {
    return (*this->data)[0];
}


int main() {
 obj *o;
 (*o->data)[0] = 10;
 (*o->method)[3] = sum;

 (*(o->method)[3])(o);
}