effective C++ item 35 例程编译不通过！求指教！

源代码如下：

#include <iostream>

#include <iomanip>

//#include <memory>

#include <functional>

class game_character;

int default_health_calc(const game_character& gc);

class game_character{

public:

	typedef std::tr1::function<int(const game_character&)> health_calc_func;

	explicit game_character(health_calc_func hcf = default_health_calc)

		:health_func(hcf)

	{}

	int health_value()const

	{

		return health_func(*this);

	}

private:

	health_calc_func health_func;

};

short calc_health(const game_character&)

{

	std::cout << "short calc_health() " << std::endl;

	return 0;

}

struct health_calculator{

	int operator()(const game_character&)const

	{

		std::cout << "the struct health_calculator int operator()" << std::endl;

		return 0;

	}

};

class game_level{

public:

	float health(const game_character&) const

	{

		std::cout << "the class game_level float health()" << std::endl;

		return 0;

	}

};

class evil_bad_guy :public game_character{

public:

	explicit evil_bad_guy(health_calc_func hcf = default_health_calc)

	:game_character(hcf)

	{}



};

class eye_candy_character :public game_character{

public:

	explicit eye_candy_character(health_calc_func hcf = default_health_calc)

		:game_character(hcf)

	{}

};



int main()

{

	evil_bad_guy ebg1(calc_health);//short calc_health()

	ebg1.health_value();

	eye_candy_character ecc1(health_calculator());

	//ecc1.health_value();//有错误！the struct health_calculator int operator()

	game_level current_level;

	evil_bad_guy ebg2(std::tr1::bind(&game_level::health, current_level, std::tr1::placeholders::_1));

	ebg2.health_value();//the class game_level float health()

}

ecc1.health_value();这一行有错误，请问是调用格式不对吗？
请各位不吝指教，谢谢！