C＃中的泛型构造函数

Question

I have the following:

GenericClass<T> : Class
{
  T Results {get; protected set;}
  public GenericClass<T> (T results, Int32 id) : base (id)
  {
    Results=results;
  }
  public static GenericClass<T> Something (Int32 id)
  {
   return new GenericClass<T> (i need to pass something like new T?, id); 
  }
}

Update T can be either type or value, so using new() is okish for some types but definetely not for values. I suppose that would imply some class redesign.

the idea was how to use the constructor? eg is it possible to pass something similar to new T (although it should not, because T is not known at the time) or what will to be the twist to avoid passing null?

Answer 1

This should work:

GenericClass<T> : Class where T : new()
{
  T Results {get; protected set;}
  public GenericClass<T> (T results, Int32 id)
  {
    Results=results;
  }
  public GenericClass<T> Something (Int32 id) : this(new T(), id)
  { }
}

Answer 2

class GenericClass<T> : Class where T : new()
{
  public T Results {get; protected set;}
  public GenericClass (T results, Int32 id) : base (id)
  {
    Results=results;
  }
  public static GenericClass<T> Something (Int32 id)
  {
   return new GenericClass<T> (new T(), id); 
  }
}

Answer 3

How about using reflection?

public static GenericClass<T> Something (Int32 id)
  {
   return new GenericClass<T> ((T)Activator.CreateInstance(typeof(T)), id); 
  }