C# child class returning a unknown type (futher: from parent)

Question

i have interface:

public interface Inx<T>
{
   T Set(Data data);
}

simple class with this metod

public class Base
{
   ??? Set(Data data) { ... }
}

and parent class like that:

public class Parent : Base, Inx<Parent>
{
   ...
}

i want to return Parent type from Set metod in child class It's possible ? I need it do to something like that:

list.Add(new Parent().Set(data));

Now i have to do that:

T t = new T();
t.Set(data);
list.Add(t);

And its little annoying, i have to use it many time

---

Sorry for spaming well hmm i can use something like that:

this.GetType().GetConstructor(new System.Type[] { typeof(Data) }).Invoke(new object[] { data })

so maybe good soluction is return a object from this method ;\ ?

well generic class with generic interface seem's be big memory waste ... beacose function of this class are same only return type is diffrent

Answer 1

Is this what you want?

interface Inx<T> { 
    T Set(Data data);
}
public class Base
{
    public virtual T Set<T>(Data data)
    {
        T t = default(T);
        return t;
    }
}
public class Parent : Base, Inx<Parent>
{
    public Parent Set(Data data)
    {
        return base.Set<Parent>(data);
    }
}
class Program
{
    static void Main(string[] args)
    {
        var data = new Data();
        var list = new List<Parent>();
        list.Add(new Parent().Set<Parent>(data));
        // or 
        list.Add(new Parent().Set(data));
    }
}

EDIT: It's better to move the interface implementation up to the Base class as Marc said:

interface Inx<T> { 
    T Set(Data data);
}
public class Base<T> : Inx<T>
{
    public virtual T Set(Data data)
    {
        T t = default(T);
        return t;
    }
}
public class Parent : Base<Parent>
{        
}
class Program
{
    static void Main(string[] args)
    {
        var data = new Data();
        var list = new List<Parent>();
        list.Add(new Parent().Set(data));            
    }
}