Question

I’m trying to clean duplicate code. The only difference are calls like

MyType x = Foo.LookupService<MyType>();

vs.

MyType x = Bar.FindService<MyType>();

So we have two methods of type T xxx<T>(), i.e. a method returning an instance of T given the class parameter T. How could I pass such functions as a parameter to a method that tries to find instances of different types, something like

foo([magic generics stuff] resolve)
{
     MyType x = resolve<MyType>();
     MyOtherType y = resolve<MyOtherType>();
}

Answer 1

In response to your updated question, I’d have to say it looks like what you’ll need to do is accept a parameter that implements an interface–something like IResolver, perhaps–which in turn provides a generic Resolve<T> method:

public interface IResolver
{
    T Resolve<T>();
}

void foo(IResolver resolver)
{
    MyType x = resolver.Resolve<MyType>();
    MyOtherType y = resolver.Resolve<MyOtherType>();
}

The reason for this is that you cannot (as far as I know) pass a generic delegate as a parameter to a non-generic method. What I mean is, you cannot have this:

void foo(Func<T> resolve)
{
}

When T is a type parameter, it has to be established within the declaration, not within the parameters themselves. Hopefully that makes sense.