Question

What’s the best way to call a generic method when the type parameter isn’t known at compile time, but instead is obtained dynamically at runtime?

Consider the following sample code – inside the Example() method, what’s the most concise way to invoke GenericMethod<T>() using the Type stored in the myType variable?

public class Sample {     public void Example(string typeName)     {         Type myType = FindType(typeName);          // What goes here to call GenericMethod<T>()?         GenericMethod<myType>(); // This doesn't work          // What changes to call StaticMethod<T>()?         Sample.StaticMethod<myType>(); // This also doesn't work     }      public void GenericMethod<T>()     {         // ...     }      public static void StaticMethod<T>()     {         //...     } } 

Answer 1

You need to use reflection to get the method to start with, then ‘construct’ it by supplying type arguments with MakeGenericMethod:

MethodInfo method = typeof(Sample).GetMethod(nameof(Sample.GenericMethod)); MethodInfo generic = method.MakeGenericMethod(myType); generic.Invoke(this, null); 

For a static method, pass null as the first argument to Invoke. That’s nothing to do with generic methods – it’s just normal reflection.

As noted, a lot of this is simpler as of C# 4 using dynamic – if you can use type inference, of course. It doesn’t help in cases where type inference isn’t available, such as the exact example in the question.