C ++确定类是否可以使用对象-文本RPG游戏 [英] C++ Determine if class can use an object - text RPG game
问题描述
我面临以下设计问题:
TL; TD需要确定在有许多英雄实现的情况下Hero(class)是否可以使用特定对象
我有3个Hero类的子类，每个子类都可以使用特定的项.
对于Weapons.hpp，我有Sword，Hammer，CrossBow，Bow，Wand，Staff.
战士可以使用剑或锤子 弓箭手可以使用CrossBow或弓箭 向导可以使用法杖或魔杖
有英雄基类:
class Hero: public Entity{
public:
Hero(std::string name, Gender gender, double damage, Point2d* location);
~Hero();
virtual void move(int x, int y);
virtual void damage(Entity* other); // Override
virtual bool use(Potion* _potion);
virtual bool use(Weapon* _weapon) = 0;
virtual bool use(ShieldArmor* _shieldArmor) = 0;
virtual bool use(BodyArmor* _bodyArmor) = 0;
private:
std::string name;
Gender gender;
Weapon* weapon;
ShieldArmor* shield_armor;
BodyArmor* body_armor;
};
这是武器:
class Weapon: public Item{
public:
Weapon(double damage, Point2d* location);
virtual ~Weapon();
virtual double getDamage() const;
virtual const Point2d* getLocation() const;
virtual const std::string toString() const;
private:
Point2d* location;
double damage;
};
在游戏的主界面中，我需要确定Hero * h是否可以使用特定项目而不会降低投放范围.
所以我可以像这样使用它:
Hero *h;
Weapon * i;
// do something assign values
h->use(i);
我通过删除不必要的所有内容并将其通用化为Item的概念，简化了示例.武器是Item的子类，药水，魔杖，助焊剂电容器也是如此. use方法执行Item对target所做的任何事情.武器将尝试击中并破坏target.治愈药水会治愈target.磁通电容器会及时将target发送回去，或者以1.21吉瓦的电量迅速删除掉其中的删除内容.
但是，所有事物都可以通过Item的镜头看到.调用类不知道项目对target的作用，作用或作用. target甚至不知道在上面使用了什么，他们只是感觉到了效果.没有人知道一个简单的通用接口之外的其他对象.
class Item
{
public:
enum types
{
whole lot of types go here.
They are fairly broad categories, like knife, sword, two handed sword,
healing potion, wand, etc.
};
types getType()
{
return type;
}
virtual bool use(Entity * target) = 0;
private:
types type;
};
class Hero: public Entity{
public:
Hero(std::set<Item::type> & usable): usableItems(usable)
~Hero();
bool use(Item* item,
Entity * target)
{
// this is the magic. If the item's type is in the list of usable items,
// the item is used on the target. They exact type of item or target
// is not known. Polymorphism will take care of everything from here
if (usableItems.find(item->getType()) != usableItems.end())
{
return item->use(target);
}
return false;
}
private:
std::set<Item::type> & usableItems;
};
重点是主要班级都非常愚蠢.它们只是为更详细的对象提供一个框架来完成详细的工作. VorpalSword使用从Weapon和Item继承的通用方法来查看它是否击中了target，不知道target实际上是HugeRedDragon实例，如果击中了则会分配损害，然后进行特定的处理. VorpalSword确实喜欢检查是否有四肢脱落的情况.
所有Hero看到的都是item->use(target).
I'm facing with the following design problem:
TL;TD need to determine if Hero(class) can use specific object while there's many heroes implementations
I have 3 subclasses of the class Hero, each one of them can use specific items.
For Weapons.hpp i have Sword,Hammer,CrossBow, Bow ,Wand , Staff.
Warrior can use Sword or hammer Archer can use CrossBow or bow Wizard can use staff or wand
There's Hero base class:
class Hero: public Entity{
public:
Hero(std::string name, Gender gender, double damage, Point2d* location);
~Hero();
virtual void move(int x, int y);
virtual void damage(Entity* other); // Override
virtual bool use(Potion* _potion);
virtual bool use(Weapon* _weapon) = 0;
virtual bool use(ShieldArmor* _shieldArmor) = 0;
virtual bool use(BodyArmor* _bodyArmor) = 0;
private:
std::string name;
Gender gender;
Weapon* weapon;
ShieldArmor* shield_armor;
BodyArmor* body_armor;
};
And this is Weapon:
class Weapon: public Item{
public:
Weapon(double damage, Point2d* location);
virtual ~Weapon();
virtual double getDamage() const;
virtual const Point2d* getLocation() const;
virtual const std::string toString() const;
private:
Point2d* location;
double damage;
};
In the Game's main i need to determine if Hero *h can use specific item without down casting if possible.
so i could use it like:
Hero *h;
Weapon * i;
// do something assign values
h->use(i);
I have simplified the example by removing everything that isn't necessary and generalized to the concept of Item. A weapon is a subclass of Item, as is a potion, a wand, a flux capacitor, whatever. The use method does whatever the Item does to target. A weapon will attempt to hit and damage target. A healing potion will heal target. A flux capacitor will either send target back in time or zap the expletive deleted out of them with 1.21 gigawatts.
But everything is seen through the lens of Item. The invoking classes doesn't know what the item is, does, or what it did to target. target doesn't even know what was used on it, they just feel the effects. Nobody knows nothin' about the other objects outside of a simple, generic interface.
class Item
{
public:
enum types
{
whole lot of types go here.
They are fairly broad categories, like knife, sword, two handed sword,
healing potion, wand, etc.
};
types getType()
{
return type;
}
virtual bool use(Entity * target) = 0;
private:
types type;
};
class Hero: public Entity{
public:
Hero(std::set<Item::type> & usable): usableItems(usable)
~Hero();
bool use(Item* item,
Entity * target)
{
// this is the magic. If the item's type is in the list of usable items,
// the item is used on the target. They exact type of item or target
// is not known. Polymorphism will take care of everything from here
if (usableItems.find(item->getType()) != usableItems.end())
{
return item->use(target);
}
return false;
}
private:
std::set<Item::type> & usableItems;
};
The point is the main classes are incredibly stupid. They simply provide a framework for much more detailed objects to do the detailed work. VorpalSword uses generic methods inherited from Weapon and Item to see if it hit target, not knowing that target is in fact a HugeRedDragon instance, and if it hit assigns damage and then does the specific things a VorpalSword does like checking for lopped off limbs.
And all Hero saw was item->use(target).
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