Algebraic data types for C99. Contribute to Hirrolot/datatype99 development by creating an account on GitHub.

enum vtable_entry
{
   BASE,
   DERIVED
};

typedef struct Base_
{
   int field;
   enum vtable_entry ent;
} Base;

typedef struct Derived_
{
   Base base;
   float field2;
} Derived;

void Base_PrintStuff(Base* obj)
{
   printf("%d ", obj->field);
}

void Derived_PrintStuff(Derived* obj)
{
   Base_PrintStuff(obj);

   printf("%f ", obj->field2);
}

void Base_Init(Base* obj)
{
   obj->ent = BASE;
   obj->field = 9;
}

void Derived_Init(Derived* obj)
{
   Base* obj_ = obj;
   Base_Init(obj_);
   obj_->ent = DERIVED;
   obj->field2 = 10.0f;
}

void Base_Virtual_PrintStuff(Base* obj)
{
   switch(obj->ent) {
       case BASE:
           Base_PrintStuff(obj);
       break;
       case DERIVED:
           Derived_PrintStuff(obj);
       break;
   }
}

int main(void)
{
   Base b;
   Base_Init(&b);

   Derived d;
   Derived_Init(&d);

   Base_Virtual_PrintStuff(&b);
   Base_Virtual_PrintStuff(&d);

   return 0;
}