#include <stdio.h>
#include <stdlib.h>

#define new(Obj,...) Obj##_##new((Obj*)malloc(sizeof(Obj)), ##__VA_ARGS__);

// --------- Class A ---------- //
// Definition
typedef struct _A {
   void (*method)();
   int x;
} A;

// Method
void A_method(A* self) {
   printf("Method invoked in A\n");
}

// Constructor
A* A_new(A* self) {
   self->x = 2;
   self->method = A_method;
   return self;
}

// -------- Class B ----------- //
// Definition
typedef struct _B {
   // Inheritance (must be first)
   A super;

   // New fields
   int y;
} B;

// Method
void B_method(B* self) {
   printf("This is method B\n");
}

// Constructor
B* B_new(B* self) {
   // Superclass constructor
   A_new((A*)self);

   // Overrides
   self->super.method = B_method;
   return self;
}

// ---------- Main ----------- //
int main() {
   A* a = (A*)new(B);
   a->method(a);
   return 0;
}