What is the difference between AppBuilder and AppGenerator in Suspenders


I’m looking at how Thoughtbot’s Suspenders works (great gem!). In fact I’ve been using it to create my own rails app composer gem for use at work.

Whilst I’ve intuitively figured out what’s going on I’d like to know why the AppBuilder class exists.As far as I can see AppBuilder is just home to methods called back in AppGenerator.

Why are they seperated like that?

Since they both subclass Rails classes, I had a peek at rails but due to few comments in the codebase and lacking documentation I’m still confused. If anyone can shed some light on this I’d really appreciate it.