python/invirt/common.py

   1 from __future__ import with_statement
   2
   3 import unittest
   4 from fcntl import flock, LOCK_EX, LOCK_SH, LOCK_UN
   5 import contextlib as clib
   6
   7 class struct(object):
   8     'A simple namespace object.'
   9     def __init__(self, d = {}, **kwargs):
  10         'd is the dictionary to update my __dict__ with.'
  11         self.__dict__.update(d)
  12         self.__dict__.update(kwargs)
  13
  14 def dicts2struct(x):
  15     """
  16     Given a tree of lists/dicts, perform a deep traversal to transform all the
  17     dicts to structs.
  18     """
  19     if type(x) == dict:
  20         return struct((k, dicts2struct(v)) for k,v in x.iteritems())
  21     elif type(x) == list:
  22         return [dicts2struct(v) for v in x]
  23     else:
  24         return x
  25
  26 @clib.contextmanager
  27 def lock_file(path, exclusive = True):
  28     with clib.closing(file(path, 'w')) as f:
  29         if exclusive:
  30             locktype = LOCK_EX
  31         else:
  32             locktype = LOCK_SH
  33         flock(f, locktype)
  34         try:
  35             yield
  36         finally:
  37             flock(f, LOCK_UN)
  38
  39 #
  40 # Tests.
  41 #
  42
  43 class common_tests(unittest.TestCase):
  44     def test_dicts2structs(self):
  45         dicts = {
  46                 'atom': 0,
  47                 'dict': { 'atom': 'atom', 'list': [1,2,3] },
  48                 'list': [ 'atom', {'key': 'value'} ]
  49                 }
  50         structs = dicts2struct(dicts)
  51         self.assertEqual(structs.atom,        dicts['atom'])
  52         self.assertEqual(structs.dict.atom,   dicts['dict']['atom'])
  53         self.assertEqual(structs.dict.list,   dicts['dict']['list'])
  54         self.assertEqual(structs.list[0],     dicts['list'][0])
  55         self.assertEqual(structs.list[1].key, dicts['list'][1]['key'])
  56
  57 if __name__ == '__main__':
  58     unittest.main()