c# - 泛型不能显式转换类型

Question

作为背景，我主要使用 Java 编程，并尝试在 C# 项目中使用/学习泛型，但遇到了困难。

这是我的问题。从主要方法中你可以看到我正在尝试设置士兵任务，但我收到了错误，

cannot convert from 'TaskHeal' to 'TaskBase<SoldierBase>'

看起来这个转换应该有效，因为 TaskHeal 是 TaskBase 的子项，但事实并非如此。这是我的完整代码:

public class Main {
    static void main(string[] args) {
        SoldierMedic myMedic = new SoldierMedic();
        myMedic.setTask(new TaskHeal(myMedic)); // Problem!
    }
}


public class SoldierBase {

    private TaskBase<SoldierBase> currentTask;
    public int status;

    public void setTask(TaskBase<SoldierBase> newTask) {
        this.currentTask = newTask;
    }
}


public class SoldierMedic : SoldierBase {
    public int healRate = 45;
}


public abstract class TaskBase<T> where T : SoldierBase {

    protected T soldier;

    public TaskBase(T unit) {
        this.soldier = unit;
        this.soldier.status = 1;
    }

    public abstract void preformTask();
}


public class TaskHeal : TaskBase<SoldierMedic> {

    public TaskHeal(SoldierMedic unit) : base(unit) { }

    public override void preformTask() {
        this.soldier.healRate++;
    }
}

Answer 1

如果您不介意为 TaskBase 和 SoldierBase 添加一个额外的非泛型基类，您可以这样做:

class Program
{
    static void Main(string[] args)
    {
        var myMedic = new SoldierMedic();
        myMedic.setTask(new TaskHeal(myMedic)); // Problem!
    }
}

public class SoldierBase
{
    public int status;
}

public class SoldierBase<T> : SoldierBase where T : SoldierBase
{
    private TaskBase currentTask;

    public void setTask(TaskBase newTask)
    {
        this.currentTask = newTask;
    }
}

public class SoldierMedic : SoldierBase<SoldierMedic>
{
    public int healRate = 45;
}

public abstract class TaskBase
{

}

public abstract class TaskBase<T> : TaskBase where T : SoldierBase<T>
{
    protected T soldier;

    public TaskBase(T unit)
    {
        this.soldier = unit;
        this.soldier.status = 1;
    }

    public abstract void preformTask();
}


public class TaskHeal : TaskBase<SoldierMedic>
{

    public TaskHeal(SoldierMedic unit) : base(unit) { }

    public override void preformTask()
    {
        this.soldier.healRate++;
    }
}

---

如果您希望它看起来更像 c#(使用属性、适当的访问修饰符和大小写)，您可以这样做:

class Program
{
    static void Main(string[] args)
    {
        var myMedic = new SoldierMedic();
        myMedic.CurrentTask = new TaskHeal(myMedic); // Problem!
    }
}

public class SoldierBase
{
    public int Status { get; set; }
}

public class SoldierBase<T> : SoldierBase where T : SoldierBase
{
    public TaskBase CurrentTask { get; set; }
}

public class SoldierMedic : SoldierBase<SoldierMedic>
{
    public int HealRate { get; set; } = 45;
}

public abstract class TaskBase
{

}

public abstract class TaskBase<T> : TaskBase where T : SoldierBase<T>
{
    protected T Soldier;

    public TaskBase(T unit)
    {
        Soldier = unit;
        Soldier.Status = 1;
    }

    public abstract void PerformTask();
}


public class TaskHeal : TaskBase<SoldierMedic>
{
    public TaskHeal(SoldierMedic unit) : base(unit) { }

    public override void PerformTask()
    {
        Soldier.HealRate++;
    }
}