Question

I’m trying to convert some applications that use Ninject to Castle Windsor so that I can eliminate some dependencies.

I can’t figure out how to achieve some of Ninject’s functionality using the container.Register methods in windsor.

Namely (in Ninject):

Kernel.Bind<ISessionProvider>().To<UnitOfWorkSessionProvider>();
Kernel.Bind<ISessionProvider>().To<ThreadSafeSessionProvider>()
  .WhenClassHas<RequireThreadSafeSession>();

This tells Ninject that when building a class that has ISessionProvider in the constructor, use UnitOfWorkSessionProvider, unless it has the attribute RequireThreadSafeSession, in which case it is given a ThreadSafeSessionProvider.

Question one- can this be done in Windsor? The documentation is a bit confusing.

Question two- how does one do this? It seems like conditional binding is permitted in the AllTypes configuration class, but the usage patterns are not quite as transparent

Answer 1

You can use UsingFactoryMethod in the registration API to use late-binding and decide on the implementation. Try this:

container.Register(Component.For<ThreadSafeSessionProvider>());
container.Register(Component.For<UnitOfWorkSessionProvider>());
container.Register(Component.For<ISessionProvider>().UsingFactoryMethod((x, u) => FindImpl(x, u)));
container.Register(Component.For<ClassUnderTest>());

private ISessionProvider FindImpl(IKernel kernel, CreationContext context)
{
   var classUnderTest = context.Handler.ComponentModel.Implementation;
   if (classUnderTest.HasAttribute<IsThreadSafeAttribute>())
   {
      return kernel.Resolve<ThreadSafeSessionProvider>();
   }

   return kernel.Resolve<UnitOfWorkSessionProvider>();
}