thiagoa

class Module < Object
  def module_eval
    # Only the language has the magic to make this work...
  end
  
  # Imagine there are a bunch of other instance methods here.
  # Module.new generates objects that respond to these methods.
end

thiagoa

UselessAble.module_eval do
  # This is written in the module's instance methods collection
  def guess_what?
    puts "I'm useless!"
  end
end

def UselessAble.who?
  puts 'I am an abstract behavior, but I do exist somehow!'
end

thiagoa

asshole_1 = AssHole.new
asshole_1.guess_what? #=> outputs "I'm useless!"
asshole_1.soul #=> outputs "I have no soul!"

asshole_2 = AssHole.new
asshole_2.guess_what? #=> outputs "I'm useless!"
asshole_2.soul #=> outputs "I have no soul!"

thiagoa

module UselessAble
  def guess_what?
    puts "I'm useless!"
  end
end

# Instances of AssHole now respond to "guess_what?" and "soul"
class AssHole
  include UselessAble

thiagoa

# Instances of Project respond to every method of Imageable!
class Project
  include Imageable
end

# Provides the same collection of methods as Imageable
module SuperImageable
  include Imageable
end

thiagoa

Imageable = Module.new

def Imageable.included(model_class)
  model_class.has_many :images
end

Imageable.module_eval do
  def main_image
    images.find { |image| image.kind == 'main_image' }
  end

thiagoa

class Project < ApplicationRecord
  include Imageable
end

project = Project.new
project.main_image #=> <Image kind="main_image" imageable_type="Project">

thiagoa

module Imageable
  # When including this module, this hook is called
  # by Ruby with the included module/class
  def self.included(model_class)
    model_class.has_many :images
  end

  def main_image
    images.find { |image| image.kind == 'main_image' }
  end

thiagoa

export default function wrapSentencesInTags(text) {
  return text
    .split('\n')
    .map(chunk => chunk.trim())
    .map(chunk => (chunk !== '') ? `<p>${chunk}</p>` : '')
    .join('');
}

thiagoa

import { expect } from 'chai';
import renderOneTweet from 'app/twitter/renderOneTweet';
import createFixture from '../../support/createFixture';

describe('renderOneTweet', () => {
  let fixture;

  beforeEach(() => { fixture = createFixture({ html: '<div id="fixture"></div>' }); });
  afterEach(() => { fixture.remove(); });