Service locator for generics

Question

I have say a dozen types T which inherit from EntityObject and IDataObject. I have generic the following interface

IDataMa         


        

Answer 1

Here is a neat solution if having the locator as singleton is fine:

static class Locator
{
    private static class LocatorEntry<T> where T : ...
    {
        public static IDataManager<T> instance;
    }

    public static void Register<T>(IDataManager<T> instance) where T : ...
    {
        LocatorEntry<T>.instance = instance;
    }

    public static IDataManager<T> GetInstance<T>() where T : ...
    {
        return LocatorEntry<T>.instance;
    }
}

If you cannot implement the locator as singleton, I believe there is no there around creating a Dictionary<Type,object> and do some casts:

class Locator
{
    private readonly Dictionary<Type, object> instances;

    public Locator
    {
        this.instances = new Dictionary<Type, object>();
    }

    public void Register<T>(IDataManager<T> instance) where T : ...
    {
        this.instances[typeof(T)] = instance;
    }

    public IDataManager<T> GetInstance<T>() where T : ...
    {
        return (IDataManager<T>)this.instances[typeof(T)];
    }
}