ruby is evil

dont_do_this.rb

class Dog
end
class Cat
  def self.new
    Dog.new
  end
end

#[3] amooreniemi (main) »  Cat.new
#=> #<Dog:0x007fa052063c78>
#[4] amooreniemi (main) »

require 'objspace'
include ObjectSpace

#[5] amooreniemi (main) »  memsize_of_all(Dog)
#=> 0
#[6] amooreniemi (main) »  memsize_of_all(Cat)
#=> 0
#[7] amooreniemi (main) »  Cat.new
#=> #<Dog:0x007febab922a18>
#[8] amooreniemi (main) »  memsize_of_all(Cat)
#=> 0
#[9] amooreniemi (main) »  memsize_of_all(Dog)
#=> 40
#[10] amooreniemi (main) »  Cat.new
#=> #<Dog:0x007febaba17bf8>
#[11] amooreniemi (main) »  memsize_of_all(Cat)
#=> 0
#[12] amooreniemi (main) »  memsize_of_all(Dog)
#=> 80
#[13] amooreniemi (main) »  Cat.new
#=> #<Dog:0x007febabab54e8>
#[14] amooreniemi (main) »  memsize_of_all(Cat)
#=> 0
#[15] amooreniemi (main) »  memsize_of_all(Dog)
#=> 120
#[16] amooreniemi (main) »

this_will_mem_leak.rb

class Dog
end
class Cat
  def initialize
    puts "dont do this"
  end
  def self.new
    super # this allocates a cat!
    Dog.new
  end
end

require 'objspace'
include ObjectSpace

#[18] amooreniemi (main) »  memsize_of_all(Cat)
#=> 0
#[19] amooreniemi (main) »  Cat.new
#dont do this
#=> #<Dog:0x007febabcffb90>
#[20] amooreniemi (main) »  memsize_of_all(Cat)
#=> 40
#[21] amooreniemi (main) »  memsize_of_all(Dog)
#=> 160
#[22] amooreniemi (main) »  Cat.new
#dont do this
#=> #<Dog:0x007febac923228>
#[23] amooreniemi (main) »  memsize_of_all(Dog)
#=> 200
#[24] amooreniemi (main) »  memsize_of_all(Cat)
#=> 80
#[25] amooreniemi (main) »