1
我不斷收到以下錯誤與下面的代碼:MEF,ImportingConstructor似乎導致了錯誤
Error: "No exports were found that match the constraint:
ContractName MefTestSample.Contracts.ICanDoSomethingImportant"
Program.cs是如下:
namespace MefTestSample
{
class Program
{
private static CompositionContainer m_Container;
static void Main(string[] args)
{
UseMockedUpTypes();
ICanDoSomethingImportant cool = m_Container.GetExport<ICanDoSomethingImportant>().Value;
cool.DoSomethingClever();
Console.ReadLine();
}
private static void UseMockedUpTypes()
{
//The commented out section works just by itself.
/*
m_Container =
new CompositionContainer(
new AssemblyCatalog(
typeof(MefTestSample.Mocks.ClassesDoNotNecessarly).Assembly));
*/
//This fails if i dont comment out the [ImportingConstructor] block.
var assemblyCatalog1 = new AssemblyCatalog(typeof (MefTestSample.Mocks.ClassesDoNotNecessarly).Assembly);
var myassembly = new AssemblyCatalog(typeof (ServiceLibrary.MoonService).Assembly);
var aggregateCatalog = new AggregateCatalog(assemblyCatalog1, myassembly);
m_Container = new CompositionContainer(aggregateCatalog);
}
}
}
下面是ClassesDoNotNecessarly代碼:
namespace MefTestSample.Mocks
{
[Export(typeof(ICanDoSomethingImportant))]
public class ClassesDoNotNecessarly : ICanDoSomethingImportant
{
//private IServicesContract _isc;
#region ICanDoSomethingImportant Members
/* This seems to be causing the problem.
[ImportingConstructor]
public ClassesDoNotNecessarly([Import("Moon")]IServicesContract isc)
{
string temp = isc.DisplayMessage();
Console.WriteLine(temp);
}
*/
public void DoSomethingClever()
{
Console.WriteLine("Hehe, I'm actually procrastinating!");
}
#endregion
}
}
MoonService如下:
namespace ServiceLibrary
{
[Export(typeof(IServicesContract))]
public class MoonService : IServicesContract
{
public string DisplayMessage()
{
return "Moon services were accessed.";
}
}
}
我相信問題是。如果我將program.cs保持原樣,並在ClassesDoNotNecessarly類中註釋掉[ImportingConstructor]屬性+構造函數,程序將顯示該類中的文本。
如果我取消註釋[ImportingConstructor]屬性n的構造函數,然後我開始得到這個問題頂部顯示的錯誤。
任何想法,將不勝感激。