Bevan Bevan - 3 months ago 9
C# Question

How do I use reflection to call a generic method?

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

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("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.

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