泛型问题

Question

我会使标题更具体，但我不知道如何把它。我试图推断泛型泛型的类型。

public class BaseAction<T>
{
   public virtual void Commit(T t1, T t2){ //do something };
}

public class SpecificAction : BaseAction<int>
{
   // I would have specific code in here dealing with ints
   // public override void virtual Commit(int t1, int t2)
}

public static class DoSomething
{
    // this obviously doesn't compile
    // I want this method to know what K is based off of T.
    // eg. T is SpecificAction of type BaseAction<int>
    // can I get int from T ?
    public static void Execute<T>(K oldObj, K newObj) where T : BaseAction<K>, new()
    {
        T action = new T();
        action.Commit(oldObj, newObj);
    }
}

我希望能够用有用的intellisense写这样的东西。有可能吗？

DoSomething.Execute<SpecificAction>(5,4);

Answer 1

我认为你能达到的最好的情况就是这样：

public static class DoSomething
{
    public static void Execute<T,K>(K oldObj, K newObj) 
                                      where T : BaseAction<K>, new()
    {
        T action = new T();
        action.Commit(oldObj, newObj);
    }
}

你必须指定：

DoSomething.Execute<SpecificAction, int>(5,4);

我怀疑会有一个编译时方法来推断基类的泛型参数。

我有另一个想法（我不建议，但记录）：

public static void Execute<T, K>(Func<T> constructor, K oldObj, K newObj) 
                            where T : BaseAction<K> // no `new()` necessary
{
    T action = constructor();
    action.Commit(oldObj, newObj);
}

您可以使用：

DoSomething.Execute(() => new SpecificAction(), 4, 5);