Generics in C# - how can I create an instance of a variable type with an argument? [duplicate]

Question

I've got a generics class, where I want to instantiate an object with the generic type. I want to use an argument for the constructor of the type.

My code:

public class GenericClass<T> where T : Some_Base_Class, new() {     public static T SomeFunction(string s)     {         if (String.IsNullOrEmpty(s))             return new T(some_param);     } } 

I get an error on the

new T(some_param) 

'T': cannot provide arguments when creating an instance of a variable type

Any ideas how can I do this?

Answer 1

Take a look at Activator.CreateInstance. For instance:

var instance = Activator.CreateInstance(typeof(T), new object[] { null, null }); 

Obviously replacing the nulls with appropriate values expected by one of the constructors of the type.

If you receive a compiler error about cannot convert object to type T, then include as T:

var instance = Activator.CreateInstance(typeof(T),                    new object[] { null, null }) as T;