尽管类/运行时匹配，但分配失败

Question

EF继承自E
SF继承自S
S具有类型E的属性subE
EF类型的运行时obj从其祖先类（E）调用AddS（S arg）-传递类型（SF）的运行时obj
分配尝试在AddS中：arg.subE = this
从所附图像中可以看到运行时类型匹配，但是分配失败。

图片密钥：E-事件； EF-EventFrameChange; S-订阅者； SF-SubscriberFrameChange; AddS（）-AddSubscriber; subE-subscriptionedEvent

最小，完整和可验证的示例

此代码在Unity中有效。在场景中创建一个空的GameObject并添加一个SpriteAnimatorScript作为组件。

using UnityEngine;

public abstract class Event : ScriptableObject
{
    public Subscriber[] subscribers;

    public void AddSubscriber(Subscriber aSub)
    //
    {
        aSub.subscribedEvent = this;
    }
}

using UnityEngine;

public class EventFrameChange : Event
{
    private SpriteAnimatorScript animatorScript;

    public void Initialize()
    // ^ 
    {
        subscribers = new Subscriber[0];
    }

}

using UnityEngine;

public abstract class Subscriber : ScriptableObject
{
    public Event subscribedEvent;
    // ^ Event this is a subscription to.

    public virtual void SetEvent(Event aEvent)
    {
        subscribedEvent = aEvent;
    }

}

using UnityEngine;

public class SubscriberFrameChange : Subscriber
{
    public new EventFrameChange subscribedEvent;
}

using UnityEngine;

public class SpriteAnimatorScript : MonoBehaviour 
{
    public EventFrameChange eventFrameChange;

    public SubscriberFrameChange subscriberFrameChange;

    void Start () 
    {
        SetupEvents();
    }

    private void SetupEvents()
    {
        eventFrameChange = ScriptableObject.CreateInstance<EventFrameChange>();
        subscriberFrameChange = ScriptableObject.CreateInstance<SubscriberFrameChange>();
        eventFrameChange.AddSubscriber(subscriberFrameChange);
    }

}

Answer 1

如果将代码仅放入普通的C＃控制台应用程序（由于缺乏Unity），我会发现aSub有两个名为subscribedEvent的属性，因为您的new字段只是阴影旧的。因此，从基类方法中进行的分配就是分配给该字段的基类副本。