有没有办法为此类/接口使用“友好”名称？

Question

Basically I just think the type name is ugly when passing it around my project. I know you can't use an interface that implements the interface because then it's a new interface that just happens to implement the original interface, right?

public class GenericFactory<T, TTypeEnum> : IGenericFactory<T, TTypeEnum>
{
    private readonly IIndex<TTypeEnum, Func<CCompParms, T>> _factory;

    public GenericFactory(IIndex<TTypeEnum, Func<CCompParms, T>> factory)
    {
        _factory = factory;
    }

    public T Create(TTypeEnum serviceType, CCompParms comp)
    {
        return _factory[serviceType](comp);
    }
}

public interface IGenericFactory<T, TTypeEnum>
{
    T Create(TTypeEnum serviceType, CCompParms comp);
}

I have tried:

public interface FriendlyName : IGenericFactory<T, TTypeEnum>
{
}

But when I try to do the following it fails to cast no matter how I cast it.

IGenericFactory<T, TTypeEnum> inter = GetTheInterface();
FriendlyName fn = (inter as FriendlyName);

Is there a way to make the type name friendly?

Answer 1

First, any general solution for a "Friendly Name" will still have to be parameterized with both of the generic types, so I don't think that's what you're looking for since it won't really save you any typing.

Assuming you want FriendlyName to already have the types bound, then I think you can get to a workable solution by using Implicit Conversions and the Decorator pattern.

WARNING!!! I just typed this into the browser (no IDE or compiler) and my C# is very rusty, so this will likely need to be tweaked

public interface FooFactory : IGenericFactory<Foo, FooEnum> {

    IGenericFactory<Foo, FooEnum> Wrapped { get; }

    // The "magic" - Note that magic always makes your code harder to understand...

    public static implicit operator FooFactory(IGenericFactory<Foo, FooEnum> wrapped) {
        // I think this can be placed here. If C# won't let you add this
        // implicit operator here, then you can easily implement this factory
        // method as an extension on IGenericFactory<Foo, FooEnum>
        return new FooFactoryWrapper(wrapped);
    }

    public static implicit operator IGenericFactory<Foo, FooEnum>(FooFactory wrapper) {
        return wrapper.Wrapped;
    }

    // I'm pretty sure we can hide this implementation here in the interface,
    // but again, my C# is pretty rusty, so you may have to move this
    // and/or change the visibility
    private class FooFactoryWrapper : FooFactory {

        public IGenericFactory<Foo, FooEnum> Wrapped { get; private set; }

        public FooFactoryWrapper(IGenericFactory<Foo, FooEnum> wrapped) {
            this.wrapped = wrapped;
        }

        // Since the "friendly type" is still an instance of the base type,
        // you'll still have to fully implement that interface. Just delegate
        // all calls to your wrapped type (most useless Decorator ever)

        public Foo Make() { return Wrapped.Make(); } // sample method in IGenericFactory<>
    }
}

Now, you should be able to use it like this:

IGenericFactory<Foo, FooEnum> inter = GetTheInterface();
FooFactory fn = inter; // implicit conversion to wrapper type

DoWork(fn); // use the "friendly name" like it were it's wrapped type
            // implicit conversion back to wrapped type

public void DoWork(IGenericFactory<Foo, FooEnum> fooFactory) {
    ...
}

---

All that being said, I wouldn't go through this effort. Whenever I've made "Friendly Name" types like this, I then make them part of my "model" and treat them as proper types, which means that I directly ask for them in method signatures and constructors.

Something like this:

public interface BarFactory : IGenericFactory<Bar, BarEnum> { }

// Asking for a BarFactory and not a IGenericFactory<Bar, BarEnum>
public void DoWork(BarFactory barFactory) { ... }

Much less typing and no need for magic.