如何在R中的向量中仅删除重复值的一个实例？(How to remove only one instance of a duplicate value in a vector in R?)

 通常，无论谁（服务器或客户端）反序列化参数或返回值，都需要知道在运行时期望的类型（而不是什么契约）才能这样做。 在这种情况下， object类型的声明参数不会为客户端提供足够的信息来反序列化服务器可能发送回的任何内容。 使用DataContractSerializer支持的类型替换它（并使用[KnownType]修饰，如果服务器计划在回调中发送子类实例）解决了这个问题。 
 
 你也可以使用配置告诉DataContractSerializer有关已知的类型，但这是应用程序范围的，对我来说似乎是一个钝器。 
 
 在我的合同看起来像这样的情况下，我有一个模糊的案例： 
 
[ServiceContract]
interface ISearch
{
    [OperationContract]
    SearchResult Search(SearchQuery query);
}

[DataContract]
[KnownType(typeof(Subclass1InSharedAssembly)), etc...]
class SearchResult
{
    [DataMember]
    BaseClassDeclaredInSharedAssembly Value { get; set; }
}
 
 因为我希望服务器和客户端使用（有用的）共享程序集类型，所以我在两者中都引用了共享程序集，并选择不为它们生成任何代理类型...所以svcutil没有生成任何KnownTypeAttribute为了我。 部分课程保存了我的培根; 在客户端上 ，您可以这样做： 
 
// generated proxy .cs
[DataContract]
partial class SearchResult
{
    ...
}

// hand-written .cs
[KnownType(typeof(Subclass1InSharedAssembly)), etc.]
partial class SearchResult
{
    // Now the client knows how to deserialise derived types.
}

In general, whoever (server or client) is deserialising a parameter or return value needs to know what types (rather, what contracts) to expect at runtime in order to do so. In this case, a declared parameter of type object doesn't give the client enough information to deserialise whatever the server might be sending back to it. Replacing it with a type supported by the DataContractSerializer (and decorated with [KnownType], if the server plans to send subclass instances in the callback) solves this problem.
 
You can also use configuration to tell the DataContractSerializer about known types, but this is application-wide and seems like a bit of a blunt instrument to me.
 
I had an obscure case once where my contracts looked something like this:
 
[ServiceContract]
interface ISearch
{
    [OperationContract]
    SearchResult Search(SearchQuery query);
}

[DataContract]
[KnownType(typeof(Subclass1InSharedAssembly)), etc...]
class SearchResult
{
    [DataMember]
    BaseClassDeclaredInSharedAssembly Value { get; set; }
}
 
Because I wanted the server and client to use the (useful) shared assembly types, I had a reference to the shared assembly in both and chose not to generate any proxy types for them... and so svcutil didn't generate any KnownTypeAttributes for me. Partial classes saved my bacon; On the client, you can do this:
 
// generated proxy .cs
[DataContract]
partial class SearchResult
{
    ...
}

// hand-written .cs
[KnownType(typeof(Subclass1InSharedAssembly)), etc.]
partial class SearchResult
{
    // Now the client knows how to deserialise derived types.
}