Question

I’ve a base presenter class:

public abstract class PresenterBase<T> where T : IView
{
    //Some code  
}

A concrete presenter class that implements this base:

public class RegistrationPresenter : PresenterBase<IRegistration>
{
    //Some Code
}

A concrete presenter factory to return the instance of presenter which depends on a specific interface contract:

public class ProductPresenterFactory : PresenterFactoryBase
{
    // Some code
    public override PresenterBase<IView> GetPresenter(IView view, string name = "")
    {
        if (view == null && string.IsNullOrEmpty(name))
            throw new ArgumentNullException();
        return presenter;
    }
} 

I need to implement the GetPresenter method. The user will put the interface contract, for example of type IRegistration in the above case. This method should figure out the class that implements PresenterBase<IRegistration> and return an instance.

Answer 1

I did not write this with a compiler; I might have made a few mistakes.

You’ll first need to get the type of the presenterbase, then we’ll scour the assemble for the implementation, then call it’s constructor. I’ll make some assumptions as written in the code.

var genericType = typeof (PresenterBase<>).MakeGenericType(new[] { view.GetType() });
var allTypes = GetType().Assembly.GetTypes(); // I assume the class is in the same assembly.
var typeToImplement = allTypes.Single(t => t.IsSubclassOf(genericType)); // I assume there is only one implementation for the given type
var constructorToCall = typeToImplement.GetConstructors().First(); // I assume there is one constructor
var presenter = constructorToCall.Invoke(new object[0]); // I assume there is no parameter