title: create class dynamically, with inheritance and particular accessors
body: <p>I'd like to build a function "create" that gives me the following capabilities :</p>
  
  <pre><code>zoo=[]
  zoo &lt;&lt; create(:dog,4)
  zoo[0].class #Dog class
  myDog=zoo[0].new("foobar") #instance of Dog
  myDog.legs #4 legs because my dog is a Dog
  zoo[0].class.legs #4
  zoo[0].class.superclass #Animal
  zoo[0].class.superclass.legs #whatever, but they have legs
  </code></pre>
  
  <p>"create(:dog,4)" produces a new class Dog that inherits Animal etc</p>
  
  <p>Can you help about this apparently simple metaprogramming question ?</p>