Generic abstract base class from Generic Interface

Question

I'm trying to understand what hierarchy would be the best for inheritance described as following. So far I have had as following:

public interface IManager<T> where T : ISomeObject
{
    bool Add(T o);
    bool Remove(T o);
    bool Update(T o);
}

But then I wanted each derived classes to have a parameterised constructor. So I went:

public abstract class Manager<T> : IManager<T> where T : ISomeObject
{
    protected readonly INeededObject obj;

    protected Manager(INeededObject o)
    {
         obj = o;
    }
}

Any ideas on how should I go about this design issue? Thanks in advance.

Answer 1

You're almost there. You can use generic type parameters in your base class as well.

public abstract class Manager<T> : IManager<T> where T : ISomeObject
{
    protected readonly T obj;

    protected Manager(T o)
    {
         obj = o;
    }
}

You can use parameterized types too, like

protected Manager(IList<T> o)
{
    ...
}

Answer 2

May be a bit of late night 'wisdom rush' (which can be wrong again). But modified my interface to be a non-generic one as followed:

public interface IManager
{
    bool Add(ISomeObject o);
    bool Remove(ISomeObject o);
    bool Update(ISomeObject o);
}

And my abstract class looks like following:

public abstract class Manager<T> : IManager<T> where T : ISomeObject
{
    protected readonly INeededObject obj;

    protected Manager(INeededObject o)
    {
         obj = o;
    }

    public abstract bool Add(T o);
    bool IManager.Add(ISomeObject obj)
    {
        return this.Add( (T) obj );
    }
}