Automatic Detection of Singletons

Today, we released a new version of Sonargraph with an improved script to find Singletons. “Singleton” is one of the design patterns described by the “Gang of Four” [1]. It represents an object that should only exist once.
There are a couple of pros and cons for a Singleton that I won’t go into detail in this blog post. For anyone interested, I recommend “Item 3: Enforce a singleton property with a private constructor or an enum type” in “Effective Java”, written by Joshua Bloch [2]. Two interesting links that came up during a quick internet research are listed as references [3] [4]. Let’s just summarize that it is important to ensure that Singletons are properly implemented to avoid bad surprises (a.k.a bugs) in your software. And you should keep an eye on the existing Singletons and check that they are not misused as global variables.

This blog post describes, how you can detect Singletons by utilizing the Groovy scripting functionality of Sonargraph.
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