将 "TYPE" 传递给 Generic_Interface 类型属性

Question

抓紧我的秃头....我有一个通用界面

interface IGenericInterface<T>
{
    T GenericTypeProperty {get; set;}
    void PerformService(); 
}

我有服务器 classes 实现通用接口并做一些事情

public class ServeRich : IGenericInterface<RichPeople>
{
    RichPeople GenericTypeProperty {get; set;}
    void PerformService() { //Serving the rich } 
}

public class ServePoor : IGenericInterface<PoorPeople>
{
    PoorPeople GenericTypeProperty {get; set;}
    void PerformService() { //Serving the Poor }
}

然后我有一个服务 class 如下，我想调用并分配其中一个服务器 class 并调用 PerformService()

public class ServeThem
{
    //This is where I am trying to figure out how to do this
    IGenericInterface<T<-??> Server {get; set;}

}

我想最终创建服务 class 并在服务器上调用执行服务方法....类似这样

main()
{
    ServeThem service= new ServeThem();
    service.Server = new ServePoor(); //This will be resolved by Ninject
    service.Server.PerformService();
}

我的问题在IGenericInterface<T<-??> Server {get; set;}。我试图弄清楚如何将 Server 属性声明为通用接口类型，可以将其分配给实现特定类型接口的 class 对象。似乎为了声明 IGenericInterface<type>，必须提及一个实际的具体类型。我尝试添加 passedInType 属性并使用 typeof(passedInType) 但这会引发异常。

如何将属性声明为通用接口类型？这可能吗

Answer 1

看来你的服务中没有使用GenericTypeProperty，所以你可以将PerformService方法移动到非泛型接口，并在服务中使用此接口class

interface INonGenericInterface
{
    void PerformService(); 
}

interface IGenericInterface<T>: INonGenericInterface
{
    T GenericTypeProperty {get; set;}
}

public class ServeThem
{
    INonGenericInterface Server {get; set;}
}

Answer 2

您正在寻找 covariance。

// T is covariant (i.e. the "out" keyword)
public interface IGenericInterface<out T>
{
    // Check that I removed the setter. T wouldn't be covariantly valid
    // if it could be set... 
    // BTW, this doesn't prevent an implementation to provide a setter.
    T GenericTypeProperty { get; }
    void PerformService(); 
}

现在将您的 ServeThem class 声明为整个属性为 IGenericInterface<object>:

public class ServeThem
{
    //This is where I am trying to figure out how to do this
    IGenericInterface<object> Server {get; set;}
}

如果无法将 GenericTypeProperty 属性设置为只读，则此方法对您不起作用。无论如何，大多数时候你可以利用方差用构造函数参数替换 setter：

public class ServeRich : IGenericInterface<RichPeople>
{
    private readonly RichPeople _people;

    public ServerRich(RichPeople people)
    {
        _people = people;
    }

    // C# 6 expression-bodied read-only property
    public RichPeople GenericTypeProperty => _people;
    public void PerformService() { //Serving the rich } 
}

将 "TYPE" 传递给 Generic_Interface 类型属性

Passing in a "TYPE" to a Generic_Interface type Property

c#

generics

dependency-injection

ninject

将 "TYPE" 传递给 Generic_Interface 类型 属性

Passing in a "TYPE" to a Generic_Interface type Property

c#

generics

dependency-injection

ninject

将 "TYPE" 传递给 Generic_Interface 类型属性