That's great to hear! I'm glad you got some use out of it. Feedback like this is the only thing that gives the book a chance of being finished. I'm generally terrible at staying focused on one thing but hearing stuff like this really helps.
I just read the component chapter and its the clearest article on components I've read so far, I wish I had read this 2yrs ago!
BTW in my game I do some component communication by having a GetComponent method on GameObject that takes a component identifier and returns the component. This is a compromise between messaging and direct reference and I think many engines offer this :)
I only just found it, read the "Game Loop" chapter and it's great stuff! I like how you clearly enumerate the pros and cons of several approaches. And even if an approach was already familiar to me, that made it very useful providing new ways of thinking and comparing about it.
"If there is one pattern this book couldn’t live without, this is it. Game loops are the quintessential example of a "game programming pattern". Almost every game has one, no two are exactly alike, and relatively few programs outside of games use them."
I've borrowed many of the game loop and other game programming principles when developing code for controlling external equipment like robots and radio transceivers. It's a better model than some of the crazy state machine code I'd written in the past.
