if I pick up an old Java project, it might be a mess, but I'll be able to rename methods, refactor classes, and upgrade libraries until it gets into shape - and I'll have a fair amount of confidence that it'll keep working while I do that, because metaprogramming is rare, APIs are fairly stable, and the IDE will mostly be able to understand what the code is doing. In a ruby project - especially in a Rails project - you can never know for sure what code is calling what. There's no "Find usages" tool that can be relied on. And then, all your dependencies will have completely changed their APIs and behaviors, and they'll have a complex matrix of incompatibilities that means that you might have to upgrade several libraries at a time and rewrite a lot of code just to keep things working.

Apologies for the slow response.

I honestly can't compare to a rails app, as I don't have the experience. I can say that modern dev practices worry me with the constant upgrade train on api standards. On the one side, progress is quite nice. On the flipside, what you describe in "all your dependencies have completely changed their APIs" is just as annoying in Java as it is in any language. More so if someone has helpfully split your codebase into as many supposedly independent parts as they can.

More than that, it is amusing that many of the refactoring tools that you reference actually began in more dynamic languages. I've seen that folks that rely on their IDE to be able to refactor have a habit of making codebases that they have to use an IDE to refactor. I grant it could just be confirmation bias.

> metaprogramming is rare

In Java? Not really. Spring has been around since 2003 or so.

Having a framework do metaprogramming, and using that framework is one thing. I think that they mean user-level metaprogramming. This is MUCH more evident in dynamic languages.

I guess he was referring not to metaprogramming in the common sense, but to the change of behaviour of built-in methods and classes.

Ah, I thought that's called "monkey patching".