C#为类的属性定义（多个）可能的类型

Question

我认为我在这里遇到了基本的 OOP 误解：

（顺便说一句，这些是 Entity Framework 6 类，以防您对“虚拟”感到惊讶）

public class WeaponUsed : HistoryEvent
{
    public virtual Player Target { get; set; }
    public virtual GameCountry Country { get; set; }
    //Victims: Troops or Pops
    public ICollection<Victim> Victims { get; set; }
    public bool HasMoreWeaponsLeft { get; set; }
}

受害者可以是“部队”对象或“人口”对象。受害者类别必须是什么样子？我可以使用 2 个属性并将未使用的属性设置为“null”，如下所示：

public class Victim
{
    public virtual Troop TroopVictim { get; set; }
    public virtual Population PopVictim { get; set; }
}

但这不可能是最好的解决方案，对吧？ 我想确定受害者可以是要么部队或人口。

我也想过通过setter来做：

public ICollection<object> Victims { get; 
    set 
    {
        if (value.GetType() == typeof(Troop) || value.GetType() == typeof(Population))
            Victims.Add(value);
    }
}

但我仍然不认为这是最好的方法，或者它可能是...... 有没有更好、更清洁的？

Answer 1

您可以使用接口。

public class WeaponUsed : HistoryEvent
{
    public virtual Player Target { get; set; }
    public virtual GameCountry Country { get; set; }
    //Victims: Troops or Pops
    public IVictim Victims { get; set; }
    public bool HasMoreWeaponsLeft { get; set; }
}

public interface IVictim {
    // common methods and properties for PopVictim and TroopVictim
    int Number {get;}
}

public class TroopVictim : IVictim {
    // TroopVictim will be enforced to have IVictim methods and proprieties
    public int Number{ get {return 1; } }
} 

public class PopVictim : IVictim {
    // PopVictim will be enforced to have IVictim methods and proprieties
    public int Number{ get {return 100; } }
} 

用法：

 Console.WriteLine(weapon.Victims.Number)

Answer 2

界面伴侣！

    public interface IVictim
    {
        string SharedProp { get; set; }
    }

    public class TroopVictim : IVictim
    {
        public string SharedProp { get; set; }

        public string TroopProperty { get; set; }
    }

    public class PopVictim : IVictim
    {
        public string SharedProp { get; set; }

        public string PopProperty { get; set; }
    }

    public class MyGenericVictim
    {
        //Optional Property
        public bool? IsTroopVictim
        {
            get
            {
                if (Victim == null) return null;
                return Victim.GetType() == typeof(TroopVictim);
            }
        }

        public IVictim Victim { get; set; }
    }


    public class UseMyOfVictim
    {
        public void Bar()
        {
            Foo(new MyGenericVictim
            {
                Victim = new TroopVictim(),
            });
        }

        public void Foo(MyGenericVictim myvic)
        {
            //Function doesnt know TroopVic or PopVic

            TroopVictim resolvedTroopVic;
            PopVictim resolvedPopVictim;

            if (myvic.Victim.GetType() == typeof(TroopVictim))
            {
                resolvedTroopVic = (TroopVictim) myvic.Victim;
            }
            else if (myvic.Victim.GetType() == typeof(PopVictim))
            {
                resolvedPopVictim = (PopVictim) myvic.Victim;
            }

            string success = resolvedPopVictim.PopProperty;
            success = resolvedTroopVic.TroopProperty;
        }
    }