Thanks again, Yehuda! I love reading these updates. Although I think there's going to be a lot of short-term pain with many of the gems and plugins I use on a daily basis [1], I am incredibly excited by the flexibility we're going to get from Rails 3.
[1] Yes yes, I know I should be trying them out and filing or fixing bugs, but I haven't had a chance yet.
Am I not allowed to have opinions that are divergent from those held by DHH five years ago? Is he required to remain static? Sure, he's arrogant, and he changed his tune despite slagging anyone who disagreed with him for years, but so what? I'm just glad that Rials is bigger than him.
I think it's being embraced more freely now because it's been achieved without losing the deep integration and sensible defaults that caused them to fall in love with Rails in the first place. I'm personally thrilled to be getting the best of both worlds.
> "Flexibility is over-rated. You're trading flexibility for productivity. Stop chasing it so religiously. Correspondingly, constraints are liberating. It encourages consistency. You don't have to worry about naming things and mapping classes." - DHH
This was in 2005. Right when Rails was starting. His point is that when you're starting a project, you can't make it uber-flexible if you want to get it done. Just write the thing, make it useful, flexibility can come later.
You can see this in the heritage of Rails directly. Rails itself was just Basecamp, and then DHH decided to make Basecamp more flexible by pulling out the non-specific stuff to be used as a library for other apps. Now that Rails works and works well, letting people be flexible with it is a natural next step.
But if they'd tried to make it this modular from the start, it never would have gotten finished!
I think what you'll see happening is that most Rails users will still continue to use what comes built in to Rails and not take advantage of being able to plug in other ORMs.
The flexibility was needed to make it easier for developers to experiment with new ways of doing things - otherwise we'd be stuck with ActiveRecord v1.0 forever.
On the other hand, I imagine a fair number of Rails developers will take advantage of the Javascript framework agnosticism and switch out Prototype+Scriptaculous for jQuery. (One could do so already without too much hassle, of course, but Rails 3 makes it plug-and-play).
[1] Yes yes, I know I should be trying them out and filing or fixing bugs, but I haven't had a chance yet.