Paul Hammant wrote a nice article about how to refactor the “nest-of-singletons design” towards using dependency injection using Google’s Guice IoC Container.
Whilst waiting for one of my many builds to finish today, I figured I’d satisfy a curiosity - roughly how many singletons are there defined within this codebase. I fired up Cygwin and used the following
find . -type f -name “*.cs” | xargs cat | grep “public static [A-Za-z]\{1,100\} Instance” | wc -l
Result:
180
Yikes!
For Java, you can always use the Google Singleton Checker which also has some nice stuff about why they’re controversial.
(Update) Paul Hammant pointed out that his article wasn’t about refactoring out singletons, rather, breaking away from using the service locator to dependency injection. Apologies for muddling it up a little :)