c# method as parameter where method contains ref paramater

Question

I have got the following method

public static void Method1(ref List<int> list)
{//code to update list}

Is it possible to create a method that takes this method as a parameter similar to (but instead of Action< List> it uses Action< ref List>)

 public static void Method2(Action<List<int>> otherMethod)
    {var newList = new List<int>(); otherMethod(newList)}

My main problem is that my method uses reference while Action> does not take references. Is this possible?

Oh, I'd love to see the implementation of `Method1` and then dissect why most probably the `ref` us totally unnecessary... — Thorsten Dittmar, May 04 '15 at 09:24

score 2 · Accepted Answer · answered May 04 '15 at 09:15

Yes, but you can't use Action<>/Func<> for it, you have to build the delegate "manually":

// Your method
public static void Method1(ref List<int> list)
{
}

// The delegate
public delegate void Method1Delegate(ref List<int> list);

// A method that accepts the delegate and uses it
public static void Method2(Method1Delegate del)
{
    List<int> list = null;
    del(ref list);
}

score 0 · Answer 2 · answered May 04 '15 at 09:15

class App
{
     private readonly Dictionary<Type, object> delegateMap;

     void Add<T>(Action<SomeClass<T>> foo)
     {
         object tmp;
         if (!delegateMap.TryGetValue(typeof(T), out tmp))
         {
              tmp = new List<Action<SomeClass<T>>>();
              delegateMap[typeof(t)] = tmp;
         }
         List<Action<SomeClass<T>> list = (List<Action<SomeClass<T>>) tmp;
         list.Add(foo);
     }

     void InvokeActions<T>(SomeClass<T> item)
     {
         object tmp;
         if (delegateMap.TryGetValue(typeof(T), out tmp))
         {
             List<Action<SomeClass<T>> list = (List<Action<SomeClass<T>>) tmp;
             foreach (var action in list)
             {
                 action(item);
             }
         }
     }
}

Use Delegates.

c# method as parameter where method contains ref paramater

2 Answers2