将对象投射到实现的接口 [英] Casting object to Implemented Interfaces

问题描述

我在将一个对象转换为实现Interface时，遇到了一个问题，跨越不同的程序集，Interfaces也在使用泛型。

我有3个库。
Contracts（接口位置）
实现（接口实现）
MainAssembly（容易成为ASP.NET MVC5应用程序）

Main参考合同和实施。

合约包含2个接口，一个使用另一个接口类型的泛型

  public interface IConfig {} 
 public interface IStore< TConfig> TConfig：IConfig {} 
  

实现包含2个实现这些接口的类，如下所示。

  public class ConfigBase：IConfig {} 
 public class Store< TConfig> ：IStore< TConfig>其中TConfig：ConfigBase {} 
  

ASP.NET应用程序有一个继承自ConfigBase类的类

  public class配置：ConfigBase {} 
  

在合同库中，有一个服务类，它包含一个需要一种类型的IStore的方法

  public void DoSomething（IStore< IConfig> store）{} 
  

商店告诉我它不能转换它。这是发生编译时错误的地方，所有appeasrs都可以正确地构建。

  Store< Configuration> store = new Store< Configuration>（）; 
 serviceObj.DoSomething（store）; 
  

解决方案

使通用接口协变使用 out 通用修饰符

  public interface IStore< out TConfig> TConfig：IConfig {}。 
  

I'm having a problem with Casting an object to it's implemented Interface, across different assemblies, the Interfaces are also using Generics.

I have 3 libraries. Contracts (Interface Location) Implementations (Interface Implementations) MainAssembly (Happens to be an ASP.NET MVC5 application)

Main references Contracts and Implementations. Implementations references Contracts.

Contracts Contains 2 Interfaces, one uses a generic that is of the other Interface type

public interface IConfig{}
public interface IStore<TConfig> where TConfig : IConfig{}

Implementations Contains 2 Classes that Implements these Interfaces like so.

public class ConfigBase : IConfig {}
public class Store<TConfig> :IStore<TConfig> where TConfig : ConfigBase {}

ASP.NET application Has a Class that Inherits from the ConfigBase class

public class Configuration : ConfigBase {}

Within the Contracts Library, there is a Service Class, that contains a Method that Requires a type of IStore

public void DoSomething(IStore<IConfig> store){}

However Passing in a type of Store is telling me it can't convert it. This is where the compile time error occurs, everything appeasrs to build correctly.

Store<Configuration> store = new Store<Configuration>();
serviceObj.DoSomething(store);

解决方案

Make you generic interface covariant using out generic modifier

public interface IStore<out TConfig> where TConfig : IConfig{}.

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