Encapsulate with closure in object, using JavaScript and Ruby

js_closure_secret.js

var myClosure = function() {
  var secret = 42, getSecret, inc;
  
  getSecret = function() { return secret; };
  
  inc = function() { secret += 1; };
  
  return {
    getSecret: getSecret,
    inc: inc
  };
}

var o = myClosure();
console.log(o.getSecret());  // 42
o.inc();
console.log(o.getSecret());  // 43

rb_closure_secret.rb

def my_closure
  secret = 42
  
  Object.new.tap do |o|
    o.send(:define_singleton_method, :get_secret) { secret }
    o.send(:define_singleton_method, :inc) { secret += 1 }
  end
end

o = my_closure
puts o.get_secret  # 42
o.inc
puts o.get_secret  # 43

rb_closure_secret_global.rb

# adapted from Metaprogramming Ruby 2 book, p83
class Foo
  def define_methods
    shared = 0
    
    Kernel.send(:define_method, :counter) { shared }
    Kernel.send(:define_method, :inc) { |x| shared += x }
  end
end

o = Foo.new
o.define_methods

puts o.counter
o.inc(4)
puts o.counter