My brain has been on the code-compile-run cycle for a long time.

So long in fact, that when I first started learning Ruby I didn’t realize that Ruby is a scripting language. People told me, and I read words like “Ruby is a scripting language” many times, but I guess i just didn’t understand.

That is, I understood the words, but I didn’t understand the full meaning. I had used scripting languages before – grudgingly – like VBScript and a tiny bit of JavaScript, and I also knew that .asp pages were “script”.

But sometimes us code-compile-run monkeys need to be hit over the head. Consider this quick example. Here’s my file, test.rb:

class App

  puts "weird... i'm inside a class declaration right now" 

  def hello
    puts "ok, now this feels normal again." 
  end

end

Ok, to use C# developers, this looks like a class declaration. But in Ruby, it’s much more than that.

Supposed you run this in a command window:

C:\dev> ruby test.rb

What do you think will happen? It’s just a class declaration, right? The hello method is never actually called.

Wrong! Ruby script is executed one statement at a time on the fly. If you run this code, you’ll get this:

C:\dev> ruby test.rb
weird... i'm inside a class declaration right now
C:\dev>

Code inside a class definition but outside any def blocks are executed.

Back in the day, when I first saw has\_many :books in Rails, I thought it was overriding a base class method or something. Had no idea it was actually executing a method, right then and there, called has\_many and passing it the parameter :books.

When I finally figured it out, a light went on, a brief angel voice could be heard in the distance, and I realized of course… it’s a script.