#!/usr/bin/env python # encoding: utf-8 # # Copyright (c) 2010 Doug Hellmann. All rights reserved. # """Show the objects with references to a given object. """ #end_pymotw_header import gc import pprint class Graph(object): def __init__(self, name): self.name = name self.next = None def set_next(self, next): print 'Linking nodes %s.next = %s' % (self, next) self.next = next def __repr__(self): return '%s(%s)' % (self.__class__.__name__, self.name) # Construct a graph cycle one = Graph('one') two = Graph('two') three = Graph('three') one.set_next(two) two.set_next(three) three.set_next(one) print # Remove references to the graph nodes in this module's namespace one = two = three = None # Show the effect of garbage collection for i in range(2): print 'Collecting %d ...' % i n = gc.collect() print 'Unreachable objects:', n print 'Remaining Garbage:', pprint.pprint(gc.garbage) print