files/usr/share/python-support/sipb-xen-base/invirt/common.py

   1 import unittest
   2 from fcntl import flock, LOCK_EX, LOCK_UN
   3 from os import remove
   4
   5 class struct(object):
   6     'A simple namespace object.'
   7     def __init__(self, d = {}, **kwargs):
   8         'd is the dictionary to update my __dict__ with.'
   9         self.__dict__.update(d)
  10         self.__dict__.update(kwargs)
  11
  12 def dicts2struct(x):
  13     """
  14     Given a tree of lists/dicts, perform a deep traversal to transform all the
  15     dicts to structs.
  16     """
  17     if type(x) == dict:
  18         return struct((k, dicts2struct(v)) for k,v in x.iteritems())
  19     elif type(x) == list:
  20         return [dicts2struct(v) for v in x]
  21     else:
  22         return x
  23
  24 #
  25 # Hacks to work around lack of Python 2.5's `with` statement.
  26 #
  27
  28 def with_closing(rsrc):
  29     """
  30     Utility to emulate Python 2.5's `with closing(rsrc)` context manager.
  31
  32     E.g.,
  33     @with_closing(file('/tmp/foo'))
  34     def contents(f):
  35         return f.read()
  36     # now 'contents' is the contents of /tmp/foo
  37     """
  38     def wrapper(func):
  39         try: return func(rsrc)
  40         finally: rsrc.close()
  41     return wrapper
  42
  43 def with_lock_file(path):
  44     """
  45     Context manager for lock files.  Example:
  46
  47     @with_lock_file('/tmp/mylock')
  48     def input():
  49         print 'locked'
  50         return raw_input()
  51     # prints 'locked'
  52     print input # prints what raw_input() returned
  53     """
  54     def wrapper(func):
  55         @with_closing(file(path, 'w'))
  56         def g(f):
  57             flock(f, LOCK_EX)
  58             try: return func()
  59             finally: flock(f, LOCK_UN)
  60         remove(path)
  61         return g
  62     return wrapper
  63
  64 #
  65 # Tests.
  66 #
  67
  68 class common_tests(unittest.TestCase):
  69     def test_dicts2structs(self):
  70         dicts = {
  71                 'atom': 0,
  72                 'dict': { 'atom': 'atom', 'list': [1,2,3] },
  73                 'list': [ 'atom', {'key': 'value'} ]
  74                 }
  75         structs = dicts2struct(dicts)
  76         self.assertEqual(structs.atom,        dicts['atom'])
  77         self.assertEqual(structs.dict.atom,   dicts['dict']['atom'])
  78         self.assertEqual(structs.dict.list,   dicts['dict']['list'])
  79         self.assertEqual(structs.list[0],     dicts['list'][0])
  80         self.assertEqual(structs.list[1].key, dicts['list'][1]['key'])
  81
  82 if __name__ == '__main__':
  83     unittest.main()