从类库访问Web应用程序的统一容器

Question

I have a class library for caching ( Redis ), we have a unity container inside this Redis class library

public class TCache<T>
{
    static readonly IUnityContainer container = new UnityContainer();

    private ITCache<T> ICacheStore;
    static TCache()
    {
        container.RegisterType<ITCache<T>, TRedisCacheStore<T>>(new ContainerControlledLifetimeManager());
    }
    public TCache()
    {
        ICacheStore = container.Resolve<TRedisCacheStore<T>>();
    }

Now my senior said me not use a separate container like this and I should be using the container which is already created inside the web app with the reason being that there should be only one single container.

My question is: is it possible to access a unity container that resides in a different project and is it necessary to do this change ?

Note: I cannot add the reference of the web app into the Redis cache class library.

Answer 1

Well, I share his view of the usage of the container. How I fixed this issue is (without going into the details of how I actually created it):

Make an option to register onto the container through an interface. Something like IRegisterContainer.Register(IUnityContainer container).

Then at the moment where you now register the mappings to the container, you extend that function to also search your assembly for all objects that implement that IRegisterContainer and make them register themselves.

And use this as a platform to fix your problem.

If you want to use the IUnityContainer in your TCache object to resolve the TRediscacheStore. Simply let the IUnityContainer register itself.

container.Register<IUnityContainer, container>(). 

And make it a dependency in the constructor of TCache.

Answer 2

You should only reference a container within your composition root ( http://blog.ploeh.dk/2011/07/28/CompositionRoot/ ).

In other words, find where your current services are registered, and perform the generic registration there.

Your type that requires a cache store then takes your abstraction via constructor injection:

public class Cache<T>
{
  private readonly ITCache<T> cacheStore;

  public Cache(ITCache<T> cacheStore)
  {
      this.cacheStore = cacheStore 
          ?? throw new ArgumentNullException(nameof(cacheStore));
  }
}

By the way, using T as a prefix for your types (rather than as a prefix for generic type parameters) is very confusing.

The names TCache and ITCache are also very confusing.