Casting objects that inherit from List<T>

[LFCfan]

I have a class Workers as below

public class Workers : List<Worker>
{
    public static Workers GetAll()
    {
        WorkersReader reader = new WorkersReader();
        -- return (Workers)reader.ExecuteReader();

        List<Worker> workerlist = reader.ExecuteReader();
        Workers workers = new Workers();

        foreach (Worker w in workerlist)
        {
            workers.Add(w);
        }
        return workers;
    }
}

Now reader.ExecuteReader() returns a List<Worker> , and as you can see in the line commented out above, I initially thought I could explicitly cast the List<Worker> as a Workers object.

I can see why I am unable to cast List<Worker> to Workers (one can cast a Workers object to a List<Worker> but not the other way round, much like (Fruit)Apple is valid but (Apple)Fruit isn't, in the case of class Apple:Fruit{})

In order to get round this I've had to loop through each of the Worker objects in the List<> and add them to a Workers object, and then return the Workers object.

While this works fine (presumably adding a bit of an overhead), is there a more elegant way I could accomplish this? I'm stumped.

Many thanks for any pointers

~LFCfan

 

[jmeckley]

what you do gain by having Workers inherit List<Worker>()?

if you need/want the Workers super class

public class Workers : List<Worker>
{
    public class Workers(IEnumerable<Worker> workers)
         : base(workers)
    {
    }

    public static Workers GetAll()
    {
        WorkersReader reader = new WorkersReader();
        return new Workers(reader.ExecuteReader());
    }
}

Jason Meckley
Programmer
Specialty Bakers, Inc.

faq855-7190

 

[LFCfan]

Thanks Jason
I ended up inheriting from Collection<T> instead.

As for what I gain by inheriting from List<T> I'm not entirely sure yet

~LFCfan