使用特定的变量值启动派生类 [英] Initiating a derived class with specific variable values

问题描述

对于以下代码段，如何使用变量（例如x，y，type）初始化Enemy类的实例？我让它正常工作，无论插入多少实例，它都会触发实例……我只需要知道用某些变量创建敌人的最佳方法，这些变量会因我的每个实例而有所不同……尤其是在某些情况下这些变量中的一个在基类中，其他则不在。

For the below code snippet, how do I initialize instances of class Enemy with variables (such as x, y, type)? I have it working correctly, it triggers the instances no matter how many of them I insert... I just need to know the best way of creating an enemy with certain variables that will differ for each of my instances... particularly when some of those variables are in the base class and others are not.

class BaseObject
{
public:
    virtual void Render() = 0;
    int x;
    int y;
};

class Enemy : public BaseObject
{
public:

    Enemy() { }
    virtual void Render()
    {
        cout << "Render! Enemy" << endl;
    }

typedef std::set<BaseObject *> GAMEOBJECTS;
GAMEOBJECTS g_gameObjects;

int main()
{
    g_gameObjects.insert(new Enemy());

    g_lootObjects.insert(new Loot());

    for(GAMEOBJECTS::iterator it = g_gameObjects.begin();
    it != g_gameObjects.end();
    it++)
    {
        (*it)->Render();
    }

    for(GAMEOBJECTS::iterator it = g_lootObjects.begin();
        it != g_lootObjects.end();
        it++)
    {
        (*it)->Render();
    }

    return 0;
}

推荐答案

在敌人中加入论点构造函数和Base构造函数。然后，您可以使用它们来初始化成员变量。

Include the arguments in the enemy constructor and Base constructors. You can then use those to initialize the member variables.

class BaseObject
{
public:
    BaseObject(int x, int y) : x(x), y(y){ }
    virtual void Render() = 0;
    int x;
    int y;
};

和

class Enemy : public BaseObject
{
public:

    Enemy(int x, int y, int foo) : BaseObject(x,y), foo(foo) { }

    int foo;
...
};

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