template <class T> 
class PtrList : 
private std::list<void*>
{
	typedef std::list<void*> base_class;
public:
	inline void push_back (T* x) { base_class::push_back(x); }
	inline void push_front (T* x) { base_class::push_front(x); }

	friend class back_insert_iterator<PtrList>;
	friend class front_insert_iterator<PtrList>;

	class iterator : private base_class::iterator
	{
	public:
		friend class PtrList;
		inline iterator& operator++()
		{ 
			base_class::iterator::operator++(); return *this;
		}
		inline iterator operator++(int x)
		{ 
			return base_class::iterator::operator++(x);
		}
		inline iterator& operator--()
		{ 
			base_class::iterator::operator--(); return *this;
		}
		inline iterator operator--(int x)
		{ 
			return base_class::iterator::operator--(x);
		}

		inline bool operator==(const iterator& right) const
		{
			return base_class::iterator::operator==(right);
		}

		inline T* operator*() { return (T*)base_class::iterator::operator*(); }

	private:
		inline iterator ( const base_class::iterator & x)
			: base_class::iterator(x)
			{}


	};


	iterator begin() { return iterator(base_class::begin()); }
	iterator end() { return iterator(base_class::end()); }

};

template<class T>
class back_insert_iterator<PtrList<T> > : 
private back_insert_iterator<std::list<void*> >
{
	typedef back_insert_iterator<std::list<void*> > back_inserter_base;
public: 
	back_insert_iterator(PtrList<T> & x)
		: back_inserter_base(x) {}
	back_insert_iterator& operator=(T*  x)
	{
		back_inserter_base::operator=(x);
		return *this;
	}
	back_insert_iterator& operator*(){ return *this; }
	back_insert_iterator& operator++(){ return *this; }
	back_insert_iterator operator++(int){ return *this; }
};

template<class T>
class front_insert_iterator<PtrList<T> > : 
private front_insert_iterator<std::list<void*> >
{
	typedef front_insert_iterator<std::list<void*> > front_inserter_base;
public: 
	front_insert_iterator(PtrList<T> & x)
		: front_inserter_base(x) {}
	front_insert_iterator& operator=(T*  x)
	{
		front_inserter_base::operator=(x);
		return *this;
	}
	front_insert_iterator& operator*(){ return *this; }
	front_insert_iterator& operator++(){ return *this; }
	front_insert_iterator operator++(int){ return *this; }
};