c# - IEquatable 和继承

问题描述

我将如何让一个父母和一个孩子继承孩子的 IEquatable 功能？这是我的代码

public class Category : IEquatable<Category>
{
   public string _Name { get; set; }
   public string _Id { get; set;}

   private string _HomeCategory { get; set; }  
   public string _prestaId { get; set; }

   public bool _inUse { get; set; }

   public Category(string Name, string Id, string HomeCategory, bool inUse)
    {
        _Name = Name;
        _Id = Id;
        _HomeCategory = HomeCategory;
        _inUse = inUse;
    }

    public virtual bool Equals(Category other)
    {
        if (other == null)
            return false;

        if(this._Id == other._Id)
        {
            return true;
        }
        else { return false; }
    }

    public override int GetHashCode()
    {
        return this._Id.GetHashCode();
    }
}

public class SubCategory : Category :   
{
    public string parentCategory { get; set; }

    public SubCategory(string Name, string Id, string HomeCategory, bool inUse) : base(Name, Id, HomeCategory, inUse)
    {

    }
}

所以我必须反对，子类别从类别派生，但包含的方法不适用于子类别，但它与类别有关工作？

标签： c#listcontainsiequatable

看来你需要IEquatable<SubCategory>在你的SubCategory. 并且SubCategory定义应该更改为public class SubCategory:Category, IEquatable<SubCategory>.

没有这个，你将有下一个行为：

var sub = new SubCategory { _Name = "1", parentCategory = "2" };
var x = new List<Category>();
x.Add(sub);
Console.WriteLine(x.Contains(new SubCategory
{
    _Name = sub._Name,
    parentCategory = sub.parentCategory
})); // prints "True"

var y = new List<SubCategory>();
y.Add(sub);
Console.WriteLine(y.Contains(new SubCategory
{
    _Name = sub._Name,
    parentCategory = sub.parentCategory
})); // prints "False"

这是有道理的，原因SubCategory是IEquatable<Category>但不是IEquatable<SubCategory>，并且IEnumerable.Contains 文档状态：

使用默认相等比较器 Default 将元素与指定值进行比较。

Which internally uses the implementation of the IEquatable<T>.Equals in your class.

c# - IEquatable 和继承

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