"""
 chaining.py
 
 An example of "chaining" method calls
 one after the other.

 The idea is that if a method returns the
 same object, then you can call another
 method on the result.

  $ python
  >>> from chaining import *
  >>> c = ChainThing()
  >>> c.increment().double().increment(3).double()
  <object ...>
  >>> c.x
  5
 
"""

class ChainThing(object):
    """ demo in class """
    
    def __init__(self, x=0):
        """        """
        self.x = x

    def double(self):
        self.x = 2 * self.x
        return self

    def increment(self, inc=1):
        self.x = self.x + inc
        return self