Generally the adapter pattern transforms one interface into another, but it can simply wrap the behavior to isolate your class from the underlying implementation. In your case, you are using an adapter, but you could just as easily have defined the DAO objects to simply implement the interface and programmed against the interface. The adapter … Read more
I think there are no specific design guidelines for this. But some of the design principles do talk about method creation. DRY ( don’t repeat yourself) is a guiding principle when comes to method creation. You group similar logic in a single method so that you don’t duplicate them all over your code and thus … Read more
DI and Strategy work in the same way, but Strategy is used for more fine-grained and short-lived dependencies. When an object is configured with a “fixed” Strategy, for example when the object is constructed, the distinction between Strategy and DI blurs. But in a DI scenario it is more unusual that the dependencies of objects … Read more
I have a single generic repository interface, which is implemented only once for a particular data storage. Here it is: public interface IRepository<T> where T : class { IQueryable<T> GetAll(); T Get(object id); void Save(T item); void Delete(T item); } I have implementations of it for EntityFramework, NHibernate, RavenDB storages. Also I have an in-memory … Read more
As per the comment on your question: I’ve a properties file containing some keys value pairs, which is need across the application, that is why I was thinking about a singleton class. This class will load the properties from a file and keep it and you can use it from anywhere in the application Don’t … Read more
Traits are similar to interfaces: Traits are Rust’s sole notion of interface. An interface is meant to document available methods, to have an interface with private methods makes no sense. Correspondingly, in Rust you can’t have different levels of visibility in one trait. If you can see the trait, you can always see all of … Read more
Hope this helps: http://msdn.microsoft.com/en-us/magazine/cc300805.aspx For those unfamiliar with TransactionScope, it is part of the System.Transactions namespace new to the Microsoft® .NET Framework 2.0. System.Transactions provides a transactions framework fully integrated into the .NET Framework, including but not limited to ADO.NET. The Transaction and TransactionScope classes are two of the most important classes in this namespace. … Read more
The Visitor pattern is typically used in such cases. Although the code is a bit more complicated, but after adding a new RecordType subclass you have to implement the logic everywhere, as it won’t compile otherwise. With instanceof all over the place it is very easy to miss one or two places. Example: public abstract … Read more
Domain-Driven Design defines a Service as: A SERVICE is an operation offered as an interface that stands alone in the model, without encapsulating state… [p. 105] Yes, it’s a class with public methods, but in addition to that, it implements an interface that exposes those methods. At its core, the Service is the interface – … Read more
Your second code snippet is, in my opinion, the best way of thread-safe lazily initializing a singleton. It actually has a pattern name Initialization-on-demand holder idiom I would suggest you use it.