source: package_tags/invirt-base/0.0.13/python/invirt/common.py @ 1806

Last change on this file since 1806 was 1623, checked in by broder, 16 years ago

Fix another typo - this one in invirt.common

File size: 2.2 KB
Line 
1from __future__ import with_statement
2
3import unittest
4from fcntl import flock, LOCK_EX, LOCK_SH, LOCK_UN
5import contextlib as clib
6
7class 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
14def 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
27def 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# Exceptions.
41#
42
43class InvalidInput(Exception):
44    """Exception for user-provided input is invalid but maybe in good faith.
45
46    This would include setting memory to negative (which might be a
47    typo) but not setting an invalid boot CD (which requires bypassing
48    the select box).
49    """
50    def __init__(self, err_field, err_value, expl=None):
51        Exception.__init__(self, expl)
52        self.err_field = err_field
53        self.err_value = err_value
54
55class CodeError(Exception):
56    """Exception for internal errors or bad faith input."""
57    pass
58
59#
60# Tests.
61#
62
63class common_tests(unittest.TestCase):
64    def test_dicts2structs(self):
65        dicts = {
66                'atom': 0,
67                'dict': { 'atom': 'atom', 'list': [1,2,3] },
68                'list': [ 'atom', {'key': 'value'} ]
69                }
70        structs = dicts2struct(dicts)
71        self.assertEqual(structs.atom,        dicts['atom'])
72        self.assertEqual(structs.dict.atom,   dicts['dict']['atom'])
73        self.assertEqual(structs.dict.list,   dicts['dict']['list'])
74        self.assertEqual(structs.list[0],     dicts['list'][0])
75        self.assertEqual(structs.list[1].key, dicts['list'][1]['key'])
76
77if __name__ == '__main__':
78    unittest.main()
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