KeyedCollection与枚举密钥类型不会指数INT [英] KeyedCollection with enum key type will not index by int

问题描述

我上课

public class FooKeyedCollection : KeyedCollection<FooType,Foo>
{
}

public enum FooType
{
   FooType1,
   FooType2,
   FooType3
}

public Foo
{
   public FooType Type { get; set; }
   public string Value { get; set; }
}

当我将项目添加到我的FooKeyedCollection，我还可对其进行索引由FooType，但是当我试图索引他们诠释，int是ptted作为FooType枚举除$ P $。其结果是，它会导致混乱的错误，即

When I add items to my FooKeyedCollection, I can index them by FooType, but when I attempt to index them int, the int is interpretted as the FooType enum. As a result, it leads to a confusing error, i.e.

public static void main()
{
   FooKeyedCollection fkc = new FooKeyedCollection();

   Foo myFoo = new Foo();
   myFoo.Type = FooType.FooType3;
   myFoo.Value = "someValue";

   foo.Add( myFoo );

   Foo myFooByType = foo[FooType.FooType3];
   Foo myFooByIndex = foo[0]; // <-- exception thrown here
}

在执行此code的结果是试图通过整数索引检索项目时异常。我希望到FooKeyedCollection公开为公共API的一部分，我要保护这个API的消费者从这一错误。有没有什么办法，我可以修改FooKeyedCollection类来获得正确的行为？

The result of executing this code is an exception when attempting to retrieve the item by integer index. I hope to expose the FooKeyedCollection as part of a public API, and I want to protect the consumers of this API from this error. Is there any way that I can modify the FooKeyedCollection class to get proper behavior?

推荐答案

您可以考虑使用新关键字的位置：

You might consider using the "new" keyword here:

public new Foo this[int index]
{
   get
   {
      IList<Foo> self = this;
      return self[index];
   }
   set
   {
       (IList<Foo>)[index] = value;
   }
}

这将允许您指数整数值。使用枚举明确将回落到KeyedCollection实施。

This will allow you to index by integer value. Using the enum explicitly will fall back to the KeyedCollection implementation.

这篇关于KeyedCollection与枚举密钥类型不会指数INT的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！