#!/usr/bin/env python # encoding: utf-8 # # Copyright (c) 2009 Doug Hellmann All rights reserved. # """ """ #end_pymotw_header import sys class ExpressionCounter(object): def __init__(self): self.count = 0 self.previous_value = self def __call__(self, value): print print ' Previous:', self.previous_value print ' New :', value print if value != self.previous_value: self.count += 1 sys.ps1 = '(%3d)> ' % self.count self.previous_value = value sys.__displayhook__(value) print 'installing' sys.displayhook = ExpressionCounter()