Question

I have a structure like below. I have some trouble returning a generic collection. What am I missing ?

class Program
{
    static void Main()
    {
          BusinessCollection businessCollection = new BusinessCollection();

          //Why this is not working because businesscollection is a GenericCollection<BusinessEntity>
          businessCollection = new GenericCollection<BusinessEntity>();

          //or neither this
         businessCollection = (BusinessCollection)new GenericCollection<BusinessEntity>();
    }
}



public class BusinessEntity
{
   public string Foo { get; set;}
}

public class BusinessCollection : GenericCollection<BusinessEntity>
{
     //some implementation here
}

public class GenericCollection<T> : ICollection<T>
{
    //some implementation here
}

Answer 1

You can’t do what you want to do. The other way around will work.

All BusinessCollection are indeed GenericCollection<BusinessEntity> but you can’t say for sure that all GenericCollection<BusinessEntity> are BusinessCollection‘s

So the following will work.

class Program
{
    static void Main()
    {
          GenericCollection<BusinessEntity> businessCollection = new BusinessCollection();
          //this will work
          BusinessCollection tempCollection = (BusinessCollection)businessCollection ;
    }
}



public class BusinessEntity
{
   public string Foo { get; set;}
}

public class BusinessCollection : GenericCollection<BusinessEntity>
{
     //some implementation here
}

public class GenericCollection<T> : ICollection<T>
{
    //some implementation here
}