Composition With StructureMap

Looking at a post by Karl Seguin where he show show designing for testability leads to a better design, in this case, composition over inheritance.

In the example, his CachedEmployeeLookup has a dependency on an EmployeeLookup, which both implement the same interface, IEmployeeLookup

How you would configure this in StructureMap so that the default class used by the program is CachedEmployeeLookup whils开发者_高级运维t CachedEmployeeLookup gets an EmployeeLookup injected to it?

I think something like this would work:

For<IEmployeeLookup>().Add<EmployeeLookup>().
   Named("employeeLookup");

For<IEmployeeLookup>().Use<CachedEmployeeLookup>()
  .Ctor<IEmployeeLookup>().Is(
     d => d.TheInstanceNamed("employeeLookup"));

You can use EnrichWith when setting up the type mappings, e.g.

ObjectFactory.Initialize(i =>
{
    i.For<IDecorator>().Use<Inner>().EnrichWith(d => new Decorator(d));
});

This page has some examples of interception in StructureMap