de-virtual

devirtual.cpp

#include <stdlib.h>

struct base_t {
  const int type;
  base_t() : type(0) {}
  base_t(int type) : type(type) {}
  virtual int call() { return 1; }
};

struct derived_t : public base_t {
  derived_t() : base_t(1) {}
  virtual int call() { return 2; }
};

base_t *one_or_other() {
  return (rand()&1) ? new base_t: (base_t*)new derived_t;
}

template <typename type_t>
int myloop(base_t *x, int itters) {
  int accum = 0;
  auto func = &type_t::call;
  auto X = static_cast<type_t*>(x);
  for (int i=0; i<itters; ++i)
    accum += (X->*func)();
  return accum;
};

int main(int argc, char**args) {
  base_t *x = one_or_other();
  if (x->type == 0)
    return myloop<base_t>(x, argc);
  else if (x->type == 1)
    return myloop<derived_t>(x, argc);
  return 0;
}