IEquatable，如何正确实施 [英] IEquatable, how to implement this properly

问题描述

我正在使用.net 2.0和c＃，并且已经在我的类中实现了IEquatible接口，如下所示：-

I am using .net 2.0 and c# and I have implemented the IEquatible interface in my class like this:-

public MyClass() :  IEquatable<MyClass>
{
    Guid m_id = Guid.NewGuid();

    public Guid Id
    {
        get
        {
            return m_id;
        }
    }

    #region IEquatable<MyClass> Members

    public bool Equals(MyClass other)
    {
        if (this.Id == other.Id)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    #endregion
}

这是不好的编程习惯吗？我已经读到我还需要实现Object.Equals和Object.GetHashCode，但是我不确定为什么。

Is this bad programming practice? I've read that I also need to implement Object.Equals and Object.GetHashCode as well, but I am not sure why.

我希望能够检查MyClass实例是否尚未包含在MyClass类型的通用列表中。为什么框架只建议您仅实现Equals？

I want to be able to check that an instance of MyClass is not already contained in a generic list of type MyClass. Why does the framework only suggests that you implement Equals only?

任何帮助将不胜感激。

推荐答案

您可以使用LINQ使用标准的自定义谓词来检查列表中是否包含项。在这种情况下，您无需覆盖等于或实现 IEquatable ：

You can check if your list contains an item using a custom predicate for the criteria, using LINQ. In that case you don't need to override Equals nor implement IEquatable:

// check if the list contains an item with a specific ID
bool found = someList.Any(item => item.ID == someId);

覆盖等于（其中 GetHashCode ）和实现 IEquatable 很有用，如果您需要将项目存储在 Dictionary 或 Hashtable 。

Overriding Equals (with GetHashCode) and implementing IEquatable is useful if you need to store your item in a Dictionary or a Hashtable.

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