How can I configure a Factory with the possible providers?
- by Jonathas Costa
I have three assemblies: "Framework.DataAccess", "Framework.DataAccess.NHibernateProvider" and "Company.DataAccess". Inside the assembly "Framework.DataAccess", I have my factory (with the wrong implementation of discovery):
public class DaoFactory
{
private static readonly object locker = new object();
private static IWindsorContainer _daoContainer;
protected static IWindsorContainer DaoContainer
{
get
{
if (_daoContainer == null)
{
lock (locker)
{
if (_daoContainer != null)
return _daoContainer;
_daoContainer = new WindsorContainer(new XmlInterpreter());
// THIS IS WRONG! THIS ASSEMBLY CANNOT KNOW ABOUT SPECIALIZATIONS!
_daoContainer.Register(
AllTypes.FromAssemblyNamed("Company.DataAccess")
.BasedOn(typeof(IReadDao<>)).WithService.FromInterface(),
AllTypes.FromAssemblyNamed("Framework.DataAccess.NHibernateProvider")
.BasedOn(typeof(IReadDao<>)).WithService.Base());
}
}
return _daoContainer;
}
}
public static T Create<T>()
where T : IDao
{
return DaoContainer.Resolve<T>();
}
}
This assembly also defines the base interface for data access IReadDao:
public interface IReadDao<T>
{
IEnumerable<T> GetAll();
}
I want to keep this assembly generic and with no references. This is my base data access assembly.
Then I have the NHibernate provider's assembly, which implements the above IReadDao using NHibernate's approach. This assembly references the "Framework.DataAccess" assembly.
public class NHibernateDao<T> : IReadDao<T>
{
public NHibernateDao()
{
}
public virtual IEnumerable<T> GetAll()
{
throw new NotImplementedException();
}
}
At last, I have the "Company.DataAccess" assembly, which can override the default implementation of NHibernate provider and references both previously seen assemblies.
public interface IProductDao : IReadDao<Product>
{
Product GetByName(string name);
}
public class ProductDao : NHibernateDao<Product>, IProductDao
{
public override IEnumerable<Product> GetAll()
{
throw new NotImplementedException("new one!");
}
public Product GetByName(string name)
{
throw new NotImplementedException();
}
}
I want to be able to write...
IRead<Product> dao = DaoFactory.Create<IRead<Product>>();
... and then get the ProductDao implementation. But I can't hold inside my base data access any reference to specific assemblies! My initial idea was to read that from a xml config file.
So, my question is: How can I externally configure this factory to use a specific provider as my default implementation and my client implementation?
