Question

I have a class which inherits from a list of list implementing an indexer

public class TwoDList<T>: List<List<T>>
{
  public T this[int row, int column]
        {
            get; 
            set ;
        }
}

on newing it and using it like this :

 TwoDCollection<int> target = new TwoDCollection<int>();
   var linearSequecValue = target[0, 2];

but i get a compile time error ” No overload for method ‘this’ takes 2 argument “

Answer 1

It works fine (assuming you provide the get and set bodies); is this:

• a typo between TwoDList<T> / TwoDCollection<T>?
• are you actually typing as List<T> / IList<T> somewhere?

I should also say: it is usually a bad idea to inherit from List<T> to provide functionality; encapsulating it would be better.

Working example:

class Program
{    
    static void Main()
    {
        TwoDList<int> target = new TwoDList<int>();
        var linearSequecValue = target[0, 2];
    }
}

public class TwoDList<T> : List<List<T>>
{
    public T this[int row, int column]
    {
        get { return this[row][column]; }
        set { this[row][column] = value; }
    }
}