Casting a Delegate into an Action or Func in runtime

Question

I\'m trying to improve my reflection code by creating Delegates for the Getter and Setter methods.

My code looks like this:

MyO         


        

Answer 1

If your objective is to be able to invoke your action/function without knowing the return type at compile time, then you probably want to end up with an Action<object> and Func<object>, right?

You can do this without having to compile an expression tree or anything, like so:

// Use reflection to create the action, invoking the method below.
var setAction = (Action<object>) this.GetType()
    .GetMethod("CastAction", BindingFlags.Static | BindingFlags.NonPublic)
    .MakeGenericMethod(prop.PropertyType)
    .Invoke(null, new object[]{setMethod});

// invoke the action like this:
object value = 42; // or any value of the right type.
setAction(value);

Using this helper method:

private static Action<object> CastAction<T>(Delegate d)
{
    var action = (Action<T>)d;
    return obj => action((T)obj);
}

My tests show this to be roughly 25% faster than using dynamic, and about 45% slower than just saying obj.Prop = 2;

Answer 2

Is there a reason why you need to use Action<T> or Func<T> to dynamically get/set a propery?

If not you can use PropertyInfo.GetMethod() and SetMethod()

 MyObject obj = new MyObject();
 PropertyInfo prop = obj.GetType().GetProperty("Prop");

 MethodInfo getter = prop.GetMethod();
 getter.Invoke(...)

 MethodInfo setter = prop.SetMethod();
 setter.Invoke(...)