NeedProvider
Description
A set of assemblies for providing interface-based dependency injection/object hydration.
How it works
Dependancy requirements are defned by implementing a series of INeed interfaces. Dependancies are accepted through those same interfaces.
Usage
This is intended for use in situations where constructor injection and other traditional avenues are not viable, for instance when injecting dependancies into entities returned by an ORM such as Lightspeed, Entity Framework or NHibernate.
Examples
A class which accepts a service of type IService
interface IService {
object Serve(object input);
}
class TestClass : INeed<IService> {
public void Accept(IService service) {
service.Serve(this);
}
}A simple static factory class is provided for scanning an assembly for types implementing INeed. The factory's output can be easily cached in a dictionary. This would usually be done at application start.
void Setup() {
Assembly assm = Assembly.GetAssembly(typeof(Main));
IEnumerable<NeedProviderSet> providerSets = NeedProviderFactory.BuildProviders(assm);
}Each NeedProviderSet maps a Type to a set of NeedProviders which can satisy its INeed requirements.
void Runtime() {
TestClass test = RetrieveTestClassFromORM();
IServiceProvider serviceProvider = GetServiceProvider();
NeedProviderSet providerSet = providerSets.First(p => p.EntityType == typeof(TestClass));
foreach (INeedProvider provider in providerSet.Providers)
provider.ProvideFor(test, serviceProvider);
}Each provider retrieves the appropriate service via the System.IServiceProvider instance, and applies it to the object through its implementation of the INeed interface method Accept(TService service).