There isn't any one spot where he explicitly states the idea that wire-up is handled centrally, but the idea is threaded throughout the article. It's discussed

There isn't any one spot where he explicitly states the idea that wire-up is handled centrally, but the idea is threaded throughout the article. It's discussed a bit more explicitly by Mark Seemann here: http://blog.ploeh.dk/2011/07/28/CompositionRoot/ http://blog.ploeh.dk/2011/07/28/CompositionRoot/ As for how this fits with abstract factories, in DI they exist to handle a specific problem: sometimes (but not always), actual instance construction has to be delayed until the last minute. But you still want things to be loosely coupled, and do the wire-up at the same place where you handle all the other object composition. So you do that by declaring an abstract factory, and then generating its concrete implementation at wire-up time. That way the details of the composition are still being injected, even if they're being executed at the site where they'll be consumed.