Question

我正在尝试创建一个系统，通过我将基类提升为派生类并使用它，但是如果你看到下面的错误，它似乎试图将'NodeType'转换为派生类型甚至虽然NodeType不是真正的类型。

这不起作用：

class Node {}
class Navpoint : Node {}
class Jumppoint : Node {}

class Actor {
  public static void on<NodeType>(Actor actor, Node node) where NodeType : Node {
     actor.Navigate(node as NodeType);  // error: (CS1502) cannot convert NodeType to Navpoint
  }

  private static IDictionary<System.Type, Navigation> navigations = 
    new Dictionary<System.Type, Navigation>() {
     {typeof(Navpoint), on<Navpoint>},
     {typeof(Jumppoint), on<Jumppoint>},
  };

  public void Navigate(Node node) {
   navigations[node.GetType()](this, node);
  }
 public void Navigate(Navpoint navpoint) {
     // do something with navpoint
  }
  public void Navigate(Jumppoint jumppoint) {
     // do something with jumppoint
 }
}

然而这确实有效：

class Node {}
class Navpoint : Node {}
class Jumppoint : Node {}

class Actor {
  public static void onNavpoint(Actor actor, Node node) {
     actor.Navigate(node as Navpoint);  // works fine
  }
  public static void onJumppoint(Actor actor, Node node) {
     actor.Navigate(node as Jumppoint);  // works fine
  }

  private static IDictionary<System.Type, Navigation> navigations = 
    new Dictionary<System.Type, Navigation>() {
     {typeof(Navpoint), onNavpoint},
     {typeof(Jumppoint), onJumppoint},
 };

  public void Navigate(Node node) {
    navigations[node.GetType()](this, node);
  }
  public void Navigate(Navpoint navpoint) {
     // do something with navpoint
 }
  public void Navigate(Jumppoint jumppoint) {
     // do something with jumppoint
 }
}

输入20个左右几乎重复的代码行并不是什么大不了的事，但我的问题是为什么？

我也在使用Unity和MonoDevelop，我不知道.NET是否会以不同的方式处理它......

C＃泛型类型转换为模板参数类型失败？

0 个答案: