title: initialize child class with parent
body: <p>Having a parent and a child class I would like to
  initialize the child class with a parent instance.
  My way seems very cumbersome (see below):</p>
  
  <p>I define a staticmethod to extract <code>init</code> parameters for parent initialization:</p>
  
  <pre><code>class Parent(object):
      @staticmethod
      get_init_params(parent_obj):
          a = parent_obj.a
          b = parent_obj.b
          return (a, b)
  
      def __init__(self, a, b):
          self.a = a
          self.b = b
  
  class Child(Parent):
      def __init__(self, parent):
          super(Parent, self).__init__(*get_init_params(parent))
  </code></pre>
  
  <p>Is there possibly a more direct way?</p>
  
  <p><strong>EDIT</strong> now the classes are simpler</p>