node_module

I'll often drop down to node.js if I really need to be close to the metal

— https://twitter.com/shit_hn_says/status/234856345579446272

Dropping down to node.js has a number of problems:

1. You introduce a new, fairly large dependency to your codebase
2. You have to maintain certain stuff in a different language
3. You open yourself up to various debates about callbacks and promises

On the other hand, it has a couple of major advantages over every other language ever:

1. It's web-scale
2. It's web-scale!

Wouldn't it be nice if you could drop down to Node... implicitly? You wouldn't need to significantly change anything to fine-tune portions of your app, right down to the individual method level.

Enter node_module, which does just that. All you need to do is add the gem, and tell it which methods or classes you want to run as JavaScript instead of Ruby.

How to install

If you use Bundler, add it to your Gemfile, then run bundle install.

gem 'node_module'

If you don't, install the gem manually.

gem install node_module

How to use

Turn certain methods into JavaScript

require 'node_module'

class AbstractConcepts

  include NodeModule

  def existentialism
    self.name = "me"
  end

  def solipsism
    (constants - [self.class]).map(&:remove_const)
  end

  def meaning_of_life
    42
  end

  # run a specific method as JavaScript
  node_module :meaning_of_life

  # run everything after this point as JavaScript
  node_module

  def pythagorean_triplet?(a, b, c)
    a**2 + b**2 == c**2
  end
end

node_module behaves like the public, private, and protected methods Ruby gives you. You can pass in specific methods as symbols, or call it without any arguments to change every subsequently defined method.

If you're using Ruby 2.1 you can also turn a single method into JS like this:

node_module def method
  # stuff
end

Turn an entire class into JavaScript

Your mileage may vary with this one. Use it at your own risk.

require 'node_module'

class MentalState < NodeModule::Compiled

  def initialize(mental_state)
    @mental_state = mental_state
  end

  def happy?
    @mental_state == "happy"
  end

  def sad?
    @mental_state == "sad"
  end

  def utterly_fucking_bonkers?
    true
  end

end

Note that you might have a lot of difficulty getting classes to talk to each other, because of the way objects are scoped when executing methods.

Current limitations

This is a ridiculous proof of concept, so there are a few issues...

• Calling one compiled method/class in the context of another will blow up, so no dependency injection or any of that.

• It's destructive, so you'll lose the body of the original method.

• It doesn't actually use Node yet, just V8.

• It probably can't handle anything too clever.

• You can't use 1.9 syntax

What Ruby code will work?

Check Opal for that. It's what does all the hard work.