Pass An Instantiated System.Type as a Type Parameter for a Generic Class

Question

The title is kind of obscure. What I want to know is if this is possible:

string typeName = <read type name from somwhere>;
Type myType = Type.GetType(typeName);

MyGenericClass<myType> myGenericClass = new MyGenericClass<myType>();

Obviously, MyGenericClass is described as:

public class MyGenericClass<T>

Right now, the compiler complains that 'The type or namespace 'myType' could not be found." There has got to be a way to do this.

Answer 1

Unfortunately no there is not. Generic arguments must be resolvable at Compile time as either 1) a valid type or 2) another generic parameter. There is no way to create generic instances based on runtime values without the big hammer of using reflection.

Answer 2

You can't do this without reflection. However, you can do it with reflection. Here's a complete example:

using System;
using System.Reflection;

public class Generic<T>
{
    public Generic()
    {
        Console.WriteLine("T={0}", typeof(T));
    }
}

class Test
{
    static void Main()
    {
        string typeName = "System.String";
        Type typeArgument = Type.GetType(typeName);

        Type genericClass = typeof(Generic<>);
        // MakeGenericType is badly named
        Type constructedClass = genericClass.MakeGenericType(typeArgument);

        object created = Activator.CreateInstance(constructedClass);
    }
}

Answer 3

*Alternatively, you could write your own generic method which does all of the work you want to do with the generic, and call that with reflection.*

Can you please give an example of this solution?