In my talk and my book on refactoring legacy PHP code, one of the early steps is to start removing globals and replace them with dependency injection (not a container, just injecting dependencies by hand.) I addressed the use of the global keyword and the $_GET (et al) superglobals, but I did not address singletons directly. I had a Reddit correspondent ask about singletons recently, and how to refactor away from them; I answered on Reddit, where you can read the full conversation.

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