何时使用IEquatable< T>又为什么

问题描述

可以买给您吗？我看到它有用的唯一原因是在创建泛型类型并强迫用户实现和编写良好的equals方法时。

What does IEquatable<T> buy you, exactly? The only reason I can see it being useful is when creating a generic type and forcing users to implement and write a good equals method.

我缺少什么？

推荐答案

从：

IEquatable< T> 的实现将减少这些类的类型转换，因此会稍快一些而不是标准的 object.Equals 方法。例如，请查看两种方法的不同实现：

The IEquatable<T> implementation will require one less cast for these classes and as a result will be slightly faster than the standard object.Equals method that would be used otherwise. As an example see the different implementation of the two methods:

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

  return (this.Id == other.Id);
}

public override bool Equals(Object obj)
{
  if (obj == null) 
     return false;

  T tObj = obj as T;  // The extra cast
  if (tObj == null)
     return false;
  else   
     return this.Id == tObj.Id;
}

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