Source Code for Module ZenUtils.Chain

 1  ########################################################################### 
 2  # 
 3  # This program is part of Zenoss Core, an open source monitoring platform. 
 4  # Copyright (C) 2007, Zenoss Inc. 
 5  # 
 6  # This program is free software; you can redistribute it and/or modify it 
 7  # under the terms of the GNU General Public License version 2 as published by 
 8  # the Free Software Foundation. 
 9  # 
10  # For complete information please visit: http://www.zenoss.com/oss/ 
11  # 
12  ########################################################################### 
13  #! /usr/bin/env python  
14   
15  __doc__='''Chain 
16   
17  Chain a series of deferred actions serially. 
18   
19  $Id$ 
20  ''' 
21   
22  __version__ = "$Revision$"[11:-2] 
23   
24   
25   
26  from twisted.internet import defer 
27   
28 -class Chain: 
29      """Call a function over an interable of data, after each finishes.""" 
30   
31 -    def __init__(self, callable, iterable): 
32          self.callable = callable 
33          self.iterable = iterable 
34          self.results = [] 
35          self.defer = defer.Deferred() 
36   
37 -    def run(self): 
38          self.next() 
39          return self.defer 
40   
41 -    def next(self): 
42          "run the next step" 
43          try: 
44              next = self.iterable.next() 
45              self.callable(next).addCallbacks(self.success, self.failure) 
46          except StopIteration: 
47              self.defer.callback(self.results) 
48          except Exception, ex: 
49              self.failure(ex) 
50   
51 -    def success(self, result): 
52          "gather a successful result" 
53          self.results.append((True, result)) 
54          self.next() 
55   
56 -    def failure(self, result): 
57          "gather an error result" 
58          self.results.append((False, result)) 
59          self.next() 
60