C＃generic - 返回派生类的对象？

Question

public class BaseClass{
  public static T Find<T>(object value){
     -- db.get<T>("params", value);
  }
}

public class Derived: BaseClass{
}

...
void someMethod(){
  Derived obj = Derived.Find<Derived>(1);
}

In the above code how do I change Derived obj = Derived.FindDerived<Derived>(1); to Derived obj = Derived.Find(1);

Answer 1

If your method signature were something like this

public static T Find<T>(T value)

Then you could omit the type in the method call. However, from your given signature, the compiler is unable to infer the type without you stating it explicitly.

Answer 2

In many cases compiler can identify type parameters and they can be omitted but not in all cases. I think return value is just one of the not supported cases becase return value is not a part of the method signature.

Here is Eric Lippert's blog post on similar issue.

Answer 3

You can eliminate it by changing BaseClass to a generic class:

public class BaseClass<T> {
    public static T Find(object value){
         -- db.get<T>("params", value);
    }
}

public class Derived: BaseClass<Derived> {

    void someMethod(){
      Derived obj = Derived.Find(1);
    }
}