Question

I have a user defined class that I want to create a public List as part of. I want the List to be a List of delegate functions that I can add to and set each List Member to a delegate function. I want this list of functions to be part of the class I instantiate, so it follows the instance of the class as I pass it to other functions. I need the ability to call the delegated functions via a foreach loop, so it also has to be IEnumberable.

I’ve been trying for several hours, what I have may or may not do part of the job. When it started looking like I needed to write my own IEnumberation routines for the custom List, I realize I was in way over my head and came here.

This is the code I have:

    public delegate List<ChartTestModel> MyDelegate<T>(T i);
    public class DelegateList<T> 
    {
        public void Add(MyDelegate<T> del)
        {
            imp.Add(del);
        }

        public void CallDelegates(T k)
        {
            foreach (MyDelegate<T> del in imp)
            {
                del(k);
            }
        }
        private List<MyDelegate<T>> imp = new List<MyDelegate<T>>();

    }

I don’t even know if this does what I want it to or not. I know I can’t ForEach through it, though. It’s written entirely from pieced together code from looking on Google. I barely understand what it’s supposed to do.

Answer 1

IEnumerable<T> is simple to implement, particularly when you have a collection as a member of the class. All you need to do is define appropriate GetEnumerator methods, and the easiest thing to do is return the enumerator of the underlying collection.

class YourClass : IEnumerable<SomeClass>
{
    List<SomeClass> list = ...

    public IEnumerator<SomeClass> GetEnumerator() 
    {
        return list.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator(); 
    }
}

Here, you implement methods for implicitly for IEnumerable<T> and explicitly for IEnumerable. (You have to implement both as IEnumerable<T> inherits IEnumerable.)

For your specific class, you might have

public class DelegateList<T> : IEnumerable<MyDelegate<T>>
{
    // ...other class details 

    private List<MyDelegate<T>> imp = new List<MyDelegate<T>>();

    public IEnumerator<MyDelegate<T>> GetEnumerator()
    {
        return imp.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }
}