Question

我有以下课程：

public abstract class ViewModel<TNavigationData> : BindableBase
        where TNavigationData : class, new()
{
   //....
}


   public class SomeClass()
   {
      public SomeClass()
      {
      }
   }

在代码的某个地方，我试图将给定的视图模型转换为具体泛型的对象。这是我在做什么：

protected virtual async Task NavigateImplAsync<TData>(IView view, TData navigationData)
            where TData : class, new()
{
     object viewModelAsObject = GetFromSomewhere() //this is ViewModel<SomeClass>

     //typeof(TData) = SomeClass

     var t4 = viewModelAsObject  as ViewModel<TData>;

     //this cast returns null however TData 

}

如果viewModelAsObject变量是该类，而TData是SomeClass类型，为什么不能将其转换为ViewModel？

Answer 1

我试图用您显示的代码作为一个通用示例：

static void Main(string[] args)
{
    SomeFunc<SomeClass>();
}

private static void SomeFunc<TData>() where TData : class, new()
{
    object gsc = IReturnSomeGenericClassWithSomeClass();

    var check = gsc as GenericClass<TData>;
    System.Console.WriteLine(check == null ? "is null" : "is not null");
}

private static GenericClass<SomeClass> IReturnSomeGenericClassWithSomeClass() { return new GenericClass<SomeClass>(); }

class SomeClass { }
class GenericClass<T> { }

此示例工作正常，我想您的函数ViewModelAsObject（）中肯定有错误。

否则，请尝试将您的代码映射到此示例或create a Minimal, Complete, and Verifiable example

使用基本类型转换通用

1 个答案: