具有以Child类型作为参数的方法的继承的类:错误的方法被调用 [英] Inherited class with methods taking Child type as a parameter: wrong method being called

问题描述

我正在制作纸牌游戏，并且有几个脚本可以控制纸牌行为.

I am making a card game, and I have several scripts that control card behavior.

public class BasicCardModel : Draggable {
    public int hitPoints;
    public GameObject cardObject;
    public static string cardName = "Basic Card";

    public CardStatus cardStatus = CardStatus.None;

    public void copyAttributes(BasicCardModel bcm) {
        Debug.Log("Calling basic copy attributes");
        hitPoints = bcm.hitPoints;
    }
    ...
}

我有几张类似于以下内容的专用卡:

I have several specialized cards similar to below:

public class AttackCardModel : BasicCardModel {
    public int attackStrength;
    public AttackType attackType;

    public void copyAttributes(AttackCardModel acm) {
        base.copyAttributes(acm);
        attackType = acm.attackType;
        Debug.Log("Attack strength = " + acm.attackStrength);
        attackStrength = acm.attackStrength;
    }
}

我有一个生成这些卡的控制器对象:

I have a controller object that generates these cards:

public class GameController : MonoBehaviour {
    public GameObject basicCard, attackCard, defenseCard, eventCard, masterCard;
    public GameObject topPlayerDeck, topPlayerHand, topPlayerField;
    public GameObject bottomPlayerDeck, bottomPlayerHand, bottomPlayerField;
    public GameObject eventDeck;
    // Use this for initialization
    void Start () {
        // Link controller to game objects
        topPlayerDeck = GameObject.Find("TopPlayerDeck");
        topPlayerHand = GameObject.Find("TopPlayerHand");
        topPlayerField = GameObject.Find("TopPlayerField");
        bottomPlayerDeck = GameObject.Find("BottomPlayerDeck");
        bottomPlayerHand = GameObject.Find("BottomPlayerHand");
        bottomPlayerField = GameObject.Find("BottomPlayerField");
        eventDeck = GameObject.Find("EventDeck");

        CardCollection cards = generateCards();

        foreach (BasicCardModel card in cards.cards) {
            if(card is AttackCardModel) {
                createCard<AttackCardModel>(topPlayerHand, card as AttackCardModel, Player.Top, CardStatus.Hand);
                createCard<AttackCardModel>(bottomPlayerHand, card as AttackCardModel, Player.Bottom, CardStatus.Hand);
            }
            else if(card is DefenseCardModel) {
                createCard<DefenseCardModel>(topPlayerHand, card as DefenseCardModel, Player.Top, CardStatus.Hand);
                createCard<DefenseCardModel>(bottomPlayerHand, card as DefenseCardModel, Player.Bottom, CardStatus.Hand);
            }
            else {
                createCard<BasicCardModel>(topPlayerHand, card as BasicCardModel, Player.Top, CardStatus.Hand);
                createCard<BasicCardModel>(bottomPlayerHand, card as BasicCardModel, Player.Bottom, CardStatus.Hand);
            }
        }

        /*
        for(int i = 0; i < 2; i++) {
            createCard<AttackCardModel>(topPlayerHand, Player.Top, CardStatus.Hand);
            createCard<AttackCardModel>(bottomPlayerHand, Player.Bottom, CardStatus.Hand);
        }
        for (int i = 0; i < 2; i++) {
            createCard<DefenseCardModel>(topPlayerHand, Player.Top, CardStatus.Hand);
            createCard<DefenseCardModel>(bottomPlayerHand, Player.Bottom, CardStatus.Hand);
        }
        */
    }

    // Update is called once per frame
    void Update () {

    }

    // For testing, have a CardCollection passed in later
    public CardCollection generateCards() {
        CardCollection cards = new CardCollection();
        //AttackCardModel testcard = new AttackCardModel(4, AttackType.SQLInjection, 3);
        cards.cards.Add(new AttackCardModel(4, AttackType.SQLInjection, 3));
        cards.cards.Add(new DefenseCardModel(5, AttackType.SQLInjection, 1));
        //Debug.Log(testcard.attackStrength + "is attack strength");
        return cards;
    }

    public void createCard<T>(GameObject whereToPut, T objectToCopy, Player player, CardStatus cardStatus) where T : BasicCardModel {
        GameObject new_card = Instantiate(basicCard);
        new_card.transform.SetParent(whereToPut.transform, false);
        Destroy(new_card.GetComponent<BasicCardModel>());
        new_card.AddComponent<T>();
        --->new_card.GetComponent<T>().copyAttributes(objectToCopy); <---
        new_card.GetComponent<T>().linkModelToCardObject(new_card);
        new_card.GetComponent<T>().setUpCard<T>(player, cardStatus);
    }
}

我在此行上遇到麻烦(在控制器对象的结尾附近): new_card.GetComponent<T>().copyAttributes(objectToCopy);

I am having trouble with this line (near the end of the controller object): new_card.GetComponent<T>().copyAttributes(objectToCopy);

它不会调用copyAttributes的子方法，而是调用父方法，因此不会复制我想要的属性.

Instead of calling the child method for copyAttributes, it calls the parent method, and thus does not copy the attributes that I want.

在我之前关于此的问题中，一个人建议使用动态类型作为解决方案.但是，即使GetComponent<ParentClass>应该获得子类型，但由于某些原因它也不起作用，因此我需要使用泛型.

In my previous question about this, one person suggested using dynamic typing as a solution. However, even though GetComponent<ParentClass> should get the child types, it doesn't work for some reason, so I need to use generics.

如何强制它调用子方法而不是父方法?

How can I force it to call the child method instead of the parent method?

推荐答案

将您的BasicCardModel的copyAttributes方法设为虚拟.

Make your BasicCardModel's copyAttributes method virtual.

public class BasicCardModel : Draggable {
    // ...    
    public virtual void copyAttributes(BasicCardModel bcm) {
        // ...    
    }
    // ...    
}

然后覆盖它AttackCardModel，并在复制其他属性之前将卡模型转换为派生类型:

Then override it AttackCardModel, and cast the card model to the derived type before copying additional attributes:

public override void copyAttributes(BasicCardModel bcm) {
    base.copyAttributes(acm);
    var acm = bcm as AttackCardModel;
    if (acm != null) {
        attackType = acm.attackType;
        Debug.Log("Attack strength = " + acm.attackStrength);
        attackStrength = acm.attackStrength;
    }
}

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