DevTools: State Of The Union 2015. Use your singletons wisely. Develop and deploy your nextapp on the IBM Bluemixcloud platform.
Start building for free The programming community discourages using global data and objects. Still, there are times when an application needs a single instance of a given class and a global point of access to that class. The general solution is the design pattern known as singletons. However, singletons are unnecessarily difficult to test and may make strong assumptions about the applications that will use them. Automated unit testing is most effective when: Coupling between classes is only as strong as it needs to beIt is simple to use mock implementations of collaborating classes in place of production implementations Certainly, when classes are loosely coupled, it is possible to concentrate on testing a single class independently. Unit tests are meant to ensure that each class behaves as it claims: independently of the rest of the system. Listing 1. Singletons know too much Where's the harm?
It’s generally well understood, but there are a number of advanced uses that have not gotten a lot of attention. In this article, I’ll review the basics and cover some truly remarkable advanced topics, including one which I think is original. The Basics We’ll start out with a simple overview of the module pattern, which has been well-known since Eric Miraglia (of YUI) first blogged about it three years ago.