c# - C# 中的非整数索引索引器属性

Question

我想在 C# 中有一个索引属性:

public Boolean IsSelected[Guid personGuid]
{
   get {
      Person person = GetPersonByGuid(personGuid);
      return person.IsSelected;
   }
   set {
      Person person = GetPersonByGuid(personGuid);
      person.IsSelected = value;
   }
}
public Boolean IsApproved[Guid personGuid]
{
   get {
      Person person = GetPersonByGuid(personGuid);
      return person.IsApproved;
   }
   set {
      Person person = GetPersonByGuid(personGuid);
      person.IsApproved= value;
   }
}

Visual Studio 提示非整数索引器语法:

我知道.NET supports non-Integer indexors .

---

我会用另一种语言写:

private
   function GetIsSelected(ApproverGUID: TGUID): Boolean;
   procedure SetIsSelected(ApproverGUID: TGUID; Value: Boolean);
   function GetIsApproved(ApproverGUID: TGUID): Boolean;
   procedure SetIsApproved(ApproverGUID: TGUID; Value: Boolean);
public
   property IsSelected[ApproverGuid: TGUID]:Boolean read GetIsSelected write SetIsSelected;
   property IsApproved[ApproverGuid: TGUID]:Boolean read GetIsApproved write SetIsApproved;
end;

Answer 1

您的语法不正确:

public Boolean this[Guid personGuid]
{
   get {
      Person person = GetPersonByGuid(personGuid);
      return person.IsSelected;
   }
   set {
      Person person = GetPersonByGuid(personGuid);
      person.IsSelected = value;
   }
}

索引器是使用 this 关键字声明的 - 您不能使用自己的名称。

来自 Using Indexers (C# Programming Guide) :

To declare an indexer on a class or struct, use the this keyword

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此外，只能有一个接受类型的索引器 - 这是 C# 索引器语法的限制(可能是 IL 限制，不确定)。