Question

I have a generic class which uses a type parameter

public class CustomClass<T> 

and I am using it with an ObservableCollection<someClass> Type. All I want is to make this class implement the IEnumerable interface, so I did the following:

public class CustomClass<T> : IEnumerable

#region Variable Declarations
 ...
#endregion

#region Constructor and CustomClass<T> properties and methods
 ...
#endregion

#region Here I add the code for IEnumerable to work

private T theObservableCollection
    {
        get
        {
            if (typeof(T) == typeof(ObservableCollection<someClass>))
                return theObservableCollection;
            else
                return default(T);
        }
    }

    //Create a public GetEnumerator method, the basic ingredient of an IEnumerable interface.
    public IEnumerator GetEnumerator()
    {
        IEnumerator r = (IEnumerator)new SettingEnumerator(this);
        return r;
    }

    //Create a nested-class
    class SettingEnumerator
    {
        int index;
        CustomClass<T> sp;

        public SettingEnumerator(CustomClass<T> str_obj)
        {
            index = -1;
            sp = str_obj;
        }

        public object Current
        {
            get
            {
                return sp.theObservableCollection[index];
            }
        }

        public bool MoveNext()
        {
            if (index < sp.theObservableCollection.Length - 1)
            {
                index++;
                return true;
            }
            return false;
        }

        public void Reset()
        {
            index = -1;
        }
    }  


#endregion

The compiler complains:

Cannot apply indexing with [] to an expression of type ‘T’

I understand that there is something wrong there, but I don’t know how to accomplish what I want, which finally is to successfully make

public class CustomClass<T> 

a

public class CustomClass<T> : IEnumerable

Answer 1

Try implementing IEnumerable<T> rather than IEnumerable