anthonylewis

require 'set'

class User
  def initialize
    @features = Set.new
  end

  def method_missing(meth, *args)
    if meth.to_s =~ /^can_(.*)\?$/
      @features.include? $1.to_s

anthonylewis

module TrackMethods
  def track(meth)
    self.class_eval do
      alias_method "old_#{meth}", meth

      define_method meth do |*args|
        puts "Calling #{meth} with #{args.join(', ')}"
        self.send "old_#{meth}", *args
      end
    end

anthonylewis

class Record
  def self.before_save(*methods)
    @callbacks ||= []
    @callbacks += methods
  end

  def self.callbacks
    @callbacks
  end

anthonylewis

module Memoize
  def calc(n)
    @@memo ||= {}
    @@memo[n] ||= super
  end
end

class Fibonacci
  prepend Memoize

anthonylewis

for i in 1..25
  puts g.next
end

anthonylewis

require 'generator'

g = Generator.new do |g|
  n = 2
  p = []

  while true
    if p.all? { |f| n % f != 0 }
      g.yield n
      p << n