# Measure the amount bloat you're adding by requiring libraries.
# 
# Usage:
#
#   Bloat.measure do
#     require 'rubygems'
#     require 'activesupport'
#   end
#
# A report will be printed that tells you how many methods were
# added, along with a list of names.
class Bloat
  def self.measure(klass=Object)
    new(klass).measure { yield }
  end
  
  def initialize(klass)
    @klass = klass
  end
  
  def delta(m)
    added(m).length
  end
  
  def added(m)
    @new_methods[m].reject { |sym| @old_methods[m].include?(sym) }.sort
  end
  
  def measure
    @old_methods = count
    yield
    @new_methods = count
    report
  end
  
  private
  
  def report
    puts "#{delta(:total)} total methods added to #{@klass}:"
    
    puts "- #{delta(:instance)} instance methods."
    added(:instance).each { |m| puts "  - #{m}" }
    
    puts "- #{delta(:class)} class methods."
    added(:class).each { |m| puts "  - #{m}" }
  end

  def count
    [:total, :instance, :class].inject({ }) do |memo, m|
      memo[m] = send("#{m}_methods")
      memo
    end
  end
  
  def total_methods
    class_methods + instance_methods
  end
  
  def class_methods
    @klass.methods
  end
  
  def instance_methods
    @klass.instance_methods
  end
end