Question

  class TypeA 
  {
      public TypeA Copy () { ... }
      public bool IsEqual(TypeA mytypeA) { ... }
      public bool IsSame(TypeA mytypeA) { ... }
      ...
  }

  class TypeACollection : List<TypeA>
  {
      public bool IsSame (TypeACollection typeAs)
      {
          if (Count != typeAs.Count) 
              return false;
          return this[0].IsSame(typeAs[0]);
      }
      ...
  }

TypeB, TypeC have the similiar funcions Copy/IsEqual/IsSame as TypeA.
TypeBCollection, TypeACollection have the similiar IsSame. The exception is TypeBCollection use TypeB.IsSame, TypeCCollection use TypeC.IsSame.

now, I plan to add 2 new classes: LocData and LocDataCollection

class LocData 
{
    public virtual TypeA Copy () { ... }
    public virtual bool IsEqual(TypeA mytypeA) { ... }
    public virtual bool IsSame(TypeA mytypeA) { ... }
    ...
}

class LocDataCollection<T> : List<LocData> where T: LocData
{
    public bool IsSame (LocDataCollection<T> typeAs)
    {
        if (Count != typeAs.Count) 
        return false;
        return this[0].IsSame(typeAs[0]);
    }
    ...
}

and rewrite existing code,

class TypeA : LocData
{
    public new TypeA Copy () { ... }
    public new bool IsEqual(TypeA mytypeA) { ... }
    public new bool IsSame(TypeA mytypeA) { ... }
    ...
}

class TypeACollection : ???
{
    ??? 
    // so I can remove IsSame here, 
    // when I call IsSame, it will use one from LocDataCollection and still call 
    // TypeA.IsSame
    ...
}

now I’m lost in abstract/virtual/generic/…, which is the best way?

Answer 1

You should replace new with overrides, then create a LocDataCollection<T> : Collection<T> where T : LocData.