如何在C＃中覆盖接口的equals运算符==？


How do I override the equals operator == for an Interface in C#?

我定义了以下接口

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public interface IHaveAProblem
{
    string Issue { get; set; }
}

下面是我要说的问题的实现

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public class SomeProblem : IHaveAProblem
{
    public string Issue { get; set; }

    public override bool Equals(object obj)
    {
        SomeProblem otherObj = obj as SomeProblem;

        if (otherObj == null)
        {
            return false;
        }

        return this.Issue == otherObj.Issue;
    }

    public override int GetHashCode()
    {
        return base.GetHashCode();
    }

    public static bool operator ==(SomeProblem rhs, SomeProblem lhs)
    {
        // Null check
        if (Object.ReferenceEquals(rhs, null) || Object.ReferenceEquals(lhs, null))
        {
            if (Object.ReferenceEquals(rhs, null) && Object.ReferenceEquals(lhs, null))
            {
                // Both are null.  They do equal each other
                return true;
            }

            // Only 1 is null the other is not so they do not equal
            return false;
        }

        return rhs.Equals(lhs);
    }

    public static bool operator !=(SomeProblem rhs, SomeProblem lhs)
    {
        // Null check
        if (Object.ReferenceEquals(rhs, null) || Object.ReferenceEquals(lhs, null))
        {
            if (Object.ReferenceEquals(rhs, null) && Object.ReferenceEquals(lhs, null))
            {
                // Both are null.  They do equal each other
                return false;
            }

            // Only 1 is null the other is not so they do not equal
            return true;
        }

        return !rhs.Equals(lhs);
    }
}

号

当我使用这个对象时，我可以得到==比较的正确结果。

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SomeProblem firstTest = new SomeProblem()
    {
        Issue ="Hello World"
    };

SomeProblem secondTest = new SomeProblem()
    {
        Issue ="Hello World"
    };

// This is true
bool result = firstTest == secondTest;

但是，当我尝试比较接口时，它正在进行内存比较，而不是在某个问题上执行运算符==

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IHaveAProblem firstProblem = new SomeProblem()
    {
        Issue ="Hello World"
    };

IHaveAProblem secondProblem = new SomeProblem()
    {
        Issue ="Hello World"
    };

。

接口是否可能在某个问题上使用==而不是内存比较？

我知道我可以做一个firstProblem.Equals(secondProblem)并得到正确的结果，但是我正在创建一个框架，我不知道它最终是如何使用的。我想==能正常工作。

相关讨论

静电==is the operator。你不能定义静态方法# for C接口。也，在least for one of the argument经营者types of needs to be the same as the class is型定义：恩，therefore社(不overloading for界面：P＞＜／

你能做的是使用抽象类的定义和安instead the operator there。再次，可能not be the operator(因为静态方法不能虚虚嗯…)P＞＜／

[评论] edited，reason)。P＞＜／

相关讨论

IIRC(我可能是错的，#界面C)不允许overloading算子。P＞＜／

但在这房子是好的。normally Maps to the operator =参考平等。你想要它听起来像价值平等，那你想力均值them to the .Equals()重写(和consequently也.GetHashCode())函数。你有你的inherit from that by IEquatable()接口。P＞＜／

konw this is an的老问题，但在秀林，how to出现两类提供了一个点的情况下，与不出现的情况下，how to双接口。P＞＜／

在一些案例中，this is the Way to dryest界面出现。P＞＜／

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public interface IHaveAProblem
{
    string Issue { get; set; }
}

public class IHaveAProblemComparer : IComparer<IHaveAProblem>, IEqualityComparer<IHaveAProblem>
{
    public int Compare(IHaveAProblem x, IHaveAProblem y)
    {
        return string.Compare(x.Issue, y.Issue);
    }

    public bool Equals(IHaveAProblem x, IHaveAProblem y)
    {
        return string.Equals(x.Issue, y.Issue);
    }

    public int GetHashCode(IHaveAProblem obj)
    {
        return obj.GetHashCode();
    }
}

使用？P＞＜／

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IHaveAProblemComparer comparer = new IHaveAProblemComparer();

List<IHaveAProblem> myListOfInterfaces = GetSomeIHaveAProblemObjects();
myListOfInterfaces.Sort(comparer); // items ordered by Issue

IHaveAProblem obj1 = new SomeProblemTypeA() { Issue ="Example1" };
IHaveAProblem obj2 = new SomeProblemTypeB() { Issue ="Example2" };

bool areEquals = comparer.Equals(obj1, obj2); // False

你有想IComparable使然？P＞＜／

这样：P＞＜／

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public interface IHaveAProblem : IComparable
{
    string Issue { get; set; }
}

然后在茶类：implementation of theP＞＜／

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public class SomeProblem : IHaveAProblem
{
    public string Issue { get; set; }

    ...

    public int CompareTo(object obj)
    {
        return Issue.CompareTo(((SomeProblem)obj).Issue);
    }
}

这说明，当你的作品，只出现两情况下，but not any other of someproblem，implementations of the ihaveaproblem接口。P＞＜／

if not sure there我在occur NullReferenceException。P＞＜／