Question

I’m experimenting with Expressions (Microsoft.Scripting.Ast) and need to assign a delegate variable with a delegate to another instance method and then call that delegate. Unfortunately I’m very clueless 🙁

var @delegate = Expression.Variable (typeof (Delegate));
var expression = Expression.Block(
     new [] { @delegate },
     Expression.Assign(@delegate, /* MISSED PART */),
     Expression.Call(@delegate, typeof(Delegate).GetMethod("DynamicInvoke"))
);

Please tell me if I missed anything. This is for my lately started internship. So it is possible that it makes no sense at all ^^

Answer 1

The answer was Expression.GetDelegateType(...)

Here is a code snippet that creates a delegate for a MethodInfo:

public static Type GetDelegateType (this MethodInfo methodInfo)
{
  var parameterTypes = methodInfo.GetParameters ().Select (x => x.ParameterType);
  var returnType = new[] { methodInfo.ReturnType };

  var delegateTypes = parameterTypes.Concat (returnType).ToArray ();
  return Expression.GetDelegateType (delegateTypes);
}