Generic List and IComparable Sorting Error: Can not convert lambda expression

Question

I have implemented my own GenericList and Task classes such as:

public GenericList<T> where T: Task
{
  public List<T> list = new List<T>();
  ....
  public void Sort()
  {
   list = list.Sort((a,b) => b.Id.CompareTo(a.Id) > 0);
   //here I am getting the Error Warning by Visual Studio IDE
   //Error: Can not convert lambda expression to
   //'System.Collections.Generic.IComparer<T>' because it is not a delegate type
  }
}

public class Task
{
  public int Id {get; set;}
  public Task(int ID)
  {Id = ID;}
}

here I am getting the Error Warning by Visual Studio IDE Error: Can not convert lambda expression to 'System.Collections.Generic.IComparer' because it is not a delegate type

I even tried to implement the following instead in the Sort() method using Compare.Create method:

list = list.OrderBy(x => x.Id,
            Comparer<Task>.Create((x, y) => x.Id > y.Id ? 1 : x.Id < y.Id ? -1 : 0));
//Here the Error: the type argument for the method can not be inferred

But I am still getting the error.

I am trying to sort the tasks based on their Ids in my implementation of Sort in GenericList. Can someone help me how may I be able to achieve this?

Any help is appreciated. Thank you in advance.

Answer 1

Try to order just by the property using lambda. No need to use

OrderBy(< TSource >, Func< TSource, TKey >)

In the OrderBy() you can just mention the property you want to order by (pun intended). In your class Task, you have already mentioned the property Id to be int, so you can just use that property to compare to.

Try something like this:

....
list = list.OrderBy(x => x.Id).ToList();
....