C++ reference counter base, with hook

countable.hh

// All rights reserved,
// Derrick Pallas
// License: zlib

#ifndef COUNTABLE_H
#define COUNTABLE_H

#include <cassert>

template <class T>
class countable {
public:
  countable() : r(0) { }
  ~countable() { assert(!r); }

  unsigned refs() { return r; }
  bool collect() { return true; }

  static T* get(T * t) {
    ++t->r;
    return t;
  }

  static bool put(T * t) {
    assert(t->refs());
    if (--t->r)
      return false;
    if (t->collect())
      delete t;
    return true;
  }

private:
  countable(const countable &);
  countable & operator=(const countable &);

  unsigned r;
};

namespace ref {
  template <class T> T* get(T * t) { return countable<T>::get(t); }
  template <class T> bool put(T * t) { return countable<T>::put(t); }
}

#endif//COUNTABLE_H