How can I invoke a method on an instance using MSIL *without* having a MethodInfo?

Question

I have a number properties on a class that follow a particular convention. Eg.

Person1 { get; set; }
Person2 { get; set; }
Person3 { get; set; }

I don't want to have to get a MethodInfo object on the instance of the class, but do something like this instead:

...
il.Emit(OpCodes.Callvirt, [instance]["set_Person" + index]);

The above line of code is illustrative and not what I think it should be.

Does anyone know how I can get around to do this?

Answer 1

It can't be done and I don't understand the point or any potential benefit. The MSIL Callvirt instruction does not take a string describing what to call, it takes a metadata token which points to a specific method on a specific type, and the only way to get that value via reflection is with a MethodInfo instance.

This really doesn't seem like a complicated alternative:

il.Emit(OpCodes.Callvirt, type.GetMethod("set_Person" + index));

Answer 2

public class Sample
{
    public int Person1 { get; set; }
    public int Person2 { get; set; }
    public int Person3 { get; set; }
}

static void Main(string[] args) {
    var s = new  Sample();
    var tuples = new List<Tuple<string, int>> { 
                    Tuple.Create("Person1", 1), 
                    Tuple.Create("Person2", 2), 
                    Tuple.Create("Person3", 3) 
                 };

    var argument = Expression.Constant(s);

    foreach (var item in tuples) {
        CreateLambda(item.Item1, argument, item.Item2)
               .Compile()
               .DynamicInvoke();
    }
 }

static LambdaExpression CreateLambda(string propertyName, Expression instance, int value) {
     return Expression.Lambda(
               Expression.Assign(
                  Expression.PropertyOrField(instance, propertyName), 
                  Expression.Constant(value)));
 }