IComparable接口的实现

Question

我现在正在阅读c#6.0一书，下面的代码主题是“实现IComparable接口”。

我不知道几件事：

1. 为什么在那里显式地实现IComparable.CompareTo？
2. 如果它只是CompareTo的另一个隐式重载(一个隐式int CompareTo (Note other)，另一个隐式int CompareTo (object other) )呢？

public struct Note : IComparable<Note>, IEquatable<Note>, IComparable
{
   int _semitonesFromA;
   public int SemitonesFromA { get { return _semitonesFromA; } }

   public Note (int semitonesFromA)
   {
     _semitonesFromA = semitonesFromA;
   }

   public int CompareTo (Note other) // Generic IComparable<T>
   {
   if (Equals (other)) return 0; // Fail-safe check
   return _semitonesFromA.CompareTo (other._semitonesFromA);
   }

   int IComparable.CompareTo (object other) // Nongeneric IComparable
   {
   if (!(other is Note))
   throw new InvalidOperationException ("CompareTo: Not a note");
   return CompareTo ((Note) other);
   }

   public static bool operator < (Note n1, Note n2)
     => n1.CompareTo (n2) < 0;

   public static bool operator > (Note n1, Note n2)
     => n1.CompareTo (n2) > 0;

   public bool Equals (Note other) // for IEquatable<Note>
     => _semitonesFromA == other._semitonesFromA;

   public override bool Equals (object other)
   {
   if (!(other is Note)) return false;
   return Equals ((Note) other);
   }

   public override int GetHashCode() => _semitonesFromA.GetHashCode();
   public static bool operator == (Note n1, Note n2) => n1.Equals (n2);
   public static bool operator != (Note n1, Note n2) => !(n1 == n2);
}

Answer 1

您可以隐式地实现IComparable，是的。但从根本上说，您希望阻止用户将Note与其他Note进行比较。如果IComparable，您可能有遗留用法，但是如果有任何直接了解Note类的信息，则不希望允许：

Note note = new Note();
Other other = new Other();
int result = note.CompareTo(other);

你知道这总是会抛出一个异常，那么为什么要允许它呢？基本上，将非泛型IComparable接口视为“某种遗留”(有有效的用途，但是.)并且通过显式地实现它来阻止任何人使用它。