如何转换多个嵌套接口 - C#

Question

我有IReport界面。这个接口是通用的，有多个属性，为了不凸屏，假设它只有一个ID 属性和T object:

public interface IReport<T>
{
  public ind ID {get;}
  public T ReportedObject {get;}
  /*And more properties I want to see when receiving a report*/
}

现在，我有另一个界面可以模拟我的数据库中的一些书籍。

public interface IBook 
{
  public string Title {get;}
  public int ID {get;}
  /*and more*/
}

/*so I made:*/

public interface IReportBook<T> : IReport<T> where T : <IBook>
{}

我有一个异步方法可以从数据库（以及更多）中获取书籍。我想给它传递一个 `IProgress` 以便我可以监控它：

/*In BookFinder.cs */
public async Task<IBook> FindThisBook(int bookID, IProgress<IReportBook<IBook>>) 
{ 
  /*Does somethings*/
}

实施：

//1) The book. This implementation is unique for the UI. 

public class UIBook : SomeClassIMustInheritFrom, IBook 
{
  /*This implementations has a lot of methods unique to it*/
}

//2) The book report for the generic book:
public class UIBookReport : IReportBook<UIBook> 
{
  /*This implementations has a UIBook property and an ID*/
}

我的目标是能够将 IReportBook 的不同实现传递给 BookFinder，具体取决于我是否在控制台、WPF 等上。

即：

/*in some UI script */

private readonly BookFinder;

public async Task<UIBook > PassBook(IBook bookInLibrary)
{
  Progress<UIBookReport> Report = new Progress<UIBookReport>();
  Report.ProgressChanged += DoSomething;
  var book = await BookFinder.FindThisBook(bookInLibrary.ID, Report); //<--
  return book as UIBook;
}

/*---------Again, here's how this method looks:---------*/
/*In BookFinder.cs */

public async Task<IBook> FindThisBook(int bookID, IProgress<IReportBook<IBook>>) 
{ 
  /*Does somethings*/
}

/*is there a way to just say 

IProgress<IReportBook> 
instead of
IProgress<IReportBook<IBook>>

? because all IReportBooks use IBook...
*/

我的错误是：

... cannot convert type 'X' to 'Y'... via a reference conversion, boxing conversion, wrapping conversion, nor null type conversion...

我应该做哪种类型的铸造？是否存在错误或以某种方式简化了整个事情？谢谢。

Answer 1

基本上我改变了 3 件事。

1) 我做了一个继承自 Progress 的 class

public class BookProgress : Progress<IBookReport>
{
  //Left it blank
}

2) 为 IBookReport 做了一个名为 UIBookReport 的实现


public interface IBook {}
public class UIBook : IBook {}

public interface IReport<T> {}
public interface IBookReport : IReport<IBook>{}
public class UIBookReport : IBookReport {}

3)


/*--------- in the ui*/

public UIBook PassBook(IBook bookInLibrary)
{
  BookFinder bookFinder = new BookFinder();
  BookProgress progress = new BookProgress();

  progress.ProgressChanged += DoSomething;

  var book = await bookFinder.FindThisBook(bookInLibrary.ID, progress); //<--
  return book as UIBook;
}

/*-------- In BookFinder.cs*/

public async Task<Book> FindBook(int bookID, IProgress<IBookReport> progress) 
{
  /*Do stuff*/

  var GenericBookReport = AppFactory.GetBookReport(/*some args*/);
  //AppFacotry is a script that returns the right implementation of some interfaces depending of the circumstances
  //In this case, it returns an UIBookReport (the class)

  progress.Report(GenericBookReport);
  /*more stuff*/
}

如何转换多个嵌套接口 - C#

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c#

generics

inheritance

casting

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