summaryrefslogtreecommitdiffstats
path: root/ipalib/parameters.py
blob: de0d14faf08d1ab79c99e65dab9cc08f406e3a1d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
# Authors:
#   Jason Gerard DeRose <jderose@redhat.com>
#
# Copyright (C) 2008  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Parameter system for command plugins.

A `Param` instance can be used to describe an argument or option that a command
takes, or an attribute that a command returns.  The `Param` base class is not
used directly, but there are many subclasses for specific Python data types
(like `Str` or `Int`) and specific properties (like `Password`).

To create a `Param` instance, you must always provide the parameter *name*,
which should be the LDAP attribute name if the parameter describes the attribute
of an LDAP entry.  For example, we could create an `Str` instance describing the user's last-name attribute like this:

>>> from ipalib import Str
>>> sn = Str('sn')
>>> sn.name
'sn'

When creating a `Param`, there are also a number of optional kwargs which
which can provide additional meta-data and functionality.  For example, every
parameter has a *cli_name*, the name used on the command-line-interface.  By
default the *cli_name* is the same as the *name*:

>>> sn.cli_name
'sn'

But often the LDAP attribute name isn't user friendly for the command-line, so
you can override this with the *cli_name* kwarg:

>>> sn = Str('sn', cli_name='last')
>>> sn.name
'sn'
>>> sn.cli_name
'last'

Note that the RPC interfaces (and the internal processing pipeline) always use
the parameter *name*, regardless of what the *cli_name* might be.

A `Param` also has two translatable kwargs: *label* and *doc*.  These must both
be `Gettext` instances.  They both default to a place-holder `FixMe` instance,
a subclass of `Gettext` used to mark a missing translatable string:

>>> sn.label
FixMe('sn')
>>> sn.doc
FixMe('sn')

The *label* is a short phrase describing the parameter.  It's used on the CLI
when interactively prompting for values, and as a label for form inputs in the
web-UI.  The *label* should start with an initial capital.  For example:

>>> from ipalib import _
>>> sn = Str('sn',
...     cli_name='last',
...     label=_('Last name'),
... )
>>> sn.label
Gettext('Last name', domain='ipa', localedir=None)

The *doc* is a longer description of the parameter.  It's used on the CLI when
displaying the help information for a command, and as extra instruction for a
form input on the web-UI.  By default the *doc* is the same as the *label*:

>>> sn.doc
Gettext('Last name', domain='ipa', localedir=None)

But you can override this with the *doc* kwarg.  Like the *label*, the *doc*
should also start with an initial capital and should not end with any
punctuation.  For example:

>>> sn = Str('sn',
...     cli_name='last',
...     label=_('Last name'),
...     doc=_("The user's last name"),
... )
>>> sn.doc
Gettext("The user's last name", domain='ipa', localedir=None)

Demonstration aside, you should always provide at least the *label* so the
various UIs are translatable.  Only provide the *doc* if the parameter needs
a more detailed description for clarity.
"""

import re
import decimal
import base64
import csv
from xmlrpclib import MAXINT, MININT

from types import NoneType
from text import _ as ugettext
from plugable import ReadOnly, lock, check_name
from errors import ConversionError, RequirementError, ValidationError
from errors import PasswordMismatch, Base64DecodeError
from constants import NULLS, TYPE_ERROR, CALLABLE_ERROR
from text import Gettext, FixMe
from ipapython.dn import DN

class DefaultFrom(ReadOnly):
    """
    Derive a default value from other supplied values.

    For example, say you wanted to create a default for the user's login from
    the user's first and last names. It could be implemented like this:

    >>> login = DefaultFrom(lambda first, last: first[0] + last)
    >>> login(first='John', last='Doe')
    'JDoe'

    If you do not explicitly provide keys when you create a `DefaultFrom`
    instance, the keys are implicitly derived from your callback by
    inspecting ``callback.func_code.co_varnames``. The keys are available
    through the ``DefaultFrom.keys`` instance attribute, like this:

    >>> login.keys
    ('first', 'last')

    The callback is available through the ``DefaultFrom.callback`` instance
    attribute, like this:

    >>> login.callback  # doctest:+ELLIPSIS
    <function <lambda> at 0x...>
    >>> login.callback.func_code.co_varnames  # The keys
    ('first', 'last')

    The keys can be explicitly provided as optional positional arguments after
    the callback. For example, this is equivalent to the ``login`` instance
    above:

    >>> login2 = DefaultFrom(lambda a, b: a[0] + b, 'first', 'last')
    >>> login2.keys
    ('first', 'last')
    >>> login2.callback.func_code.co_varnames  # Not the keys
    ('a', 'b')
    >>> login2(first='John', last='Doe')
    'JDoe'

    If any keys are missing when calling your `DefaultFrom` instance, your
    callback is not called and ``None`` is returned.  For example:

    >>> login(first='John', lastname='Doe') is None
    True
    >>> login() is None
    True

    Any additional keys are simply ignored, like this:

    >>> login(last='Doe', first='John', middle='Whatever')
    'JDoe'

    As above, because `DefaultFrom.__call__` takes only pure keyword
    arguments, they can be supplied in any order.

    Of course, the callback need not be a ``lambda`` expression. This third
    example is equivalent to both the ``login`` and ``login2`` instances
    above:

    >>> def get_login(first, last):
    ...     return first[0] + last
    ...
    >>> login3 = DefaultFrom(get_login)
    >>> login3.keys
    ('first', 'last')
    >>> login3.callback.func_code.co_varnames
    ('first', 'last')
    >>> login3(first='John', last='Doe')
    'JDoe'
    """

    def __init__(self, callback, *keys):
        """
        :param callback: The callable to call when all keys are present.
        :param keys: Optional keys used for source values.
        """
        if not callable(callback):
            raise TypeError(
                CALLABLE_ERROR % ('callback', callback, type(callback))
            )
        self.callback = callback
        if len(keys) == 0:
            fc = callback.func_code
            if fc.co_flags & 0x0c:
                raise ValueError("callback: variable-length argument list not allowed")
            self.keys = fc.co_varnames[:fc.co_argcount]
        else:
            self.keys = keys
        for key in self.keys:
            if type(key) is not str:
                raise TypeError(
                    TYPE_ERROR % ('keys', str, key, type(key))
                )
        lock(self)

    def __repr__(self):
        args = (self.callback.__name__,) + tuple(repr(k) for k in self.keys)
        return '%s(%s)' % (
            self.__class__.__name__,
            ', '.join(args)
        )

    def __call__(self, **kw):
        """
        Call the callback if all keys are present.

        If all keys are present, the callback is called and its return value is
        returned.  If any keys are missing, ``None`` is returned.

        :param kw: The keyword arguments.
        """
        vals = tuple(kw.get(k, None) for k in self.keys)
        if None in vals:
            return
        try:
            return self.callback(*vals)
        except StandardError:
            pass


def parse_param_spec(spec):
    """
    Parse shorthand ``spec`` into to ``(name, kw)``.

    The ``spec`` string determines the parameter name, whether the parameter is
    required, and whether the parameter is multivalue according the following
    syntax:

    ======  =====  ========  ==========
    Spec    Name   Required  Multivalue
    ======  =====  ========  ==========
    'var'   'var'  True      False
    'var?'  'var'  False     False
    'var*'  'var'  False     True
    'var+'  'var'  True      True
    ======  =====  ========  ==========

    For example,

    >>> parse_param_spec('login')
    ('login', {'required': True, 'multivalue': False})
    >>> parse_param_spec('gecos?')
    ('gecos', {'required': False, 'multivalue': False})
    >>> parse_param_spec('telephone_numbers*')
    ('telephone_numbers', {'required': False, 'multivalue': True})
    >>> parse_param_spec('group+')
    ('group', {'required': True, 'multivalue': True})

    :param spec: A spec string.
    """
    if type(spec) is not str:
        raise TypeError(
            TYPE_ERROR % ('spec', str, spec, type(spec))
        )
    _map = {
        '?': dict(required=False, multivalue=False),
        '*': dict(required=False, multivalue=True),
        '+': dict(required=True, multivalue=True),
    }
    end = spec[-1]
    if end in _map:
        return (spec[:-1], _map[end])
    return (spec, dict(required=True, multivalue=False))


__messages = set()

def _(message):
    __messages.add(message)
    return message


class Param(ReadOnly):
    """
    Base class for all parameters.

    Param attributes:
    =================
    The behavior of Param class and subclasses can be controlled using the
    following set of attributes:

      - cli_name: option name in CLI
      - cli_short_name: one character version of cli_name
      - label: very short description of the parameter. This value is used in
        when the Command output is printed to CLI or in a Command help
      - doc: parameter long description used in help
      - required: the parameter is marked as required for given Command
      - multivalue: indicates if the attribute is multivalued
      - primary_key: Command's parameter primary key is used for unique
        identification of an LDAP object and for sorting
      - normalizer: a custom function for Param value normalization
      - default_from: a custom function for generating default values of
        parameter instance
      - autofill: by default, only `required` parameters get a default value
        from the default_from function. When autofill is enabled, optional
        attributes get the default value filled too
      - query: this attribute is controlled by framework. When the `query`
        is enabled, framework assumes that the value is only queried and not
        inserted in the LDAP. Validation is then relaxed - custom
        parameter validators are skipped and only basic class validators are
        executed to check the parameter value
      - attribute: this attribute is controlled by framework and enabled for
        all LDAP objects parameters (unless parameter has "virtual_attribute"
        flag). All parameters with enabled `attribute` are being encoded and
        placed to an entry passed to LDAP Create/Update calls
      - include: a list of contexts where this parameter should be included.
        `Param.use_in_context()` provides further information.
      - exclude: a list of contexts where this parameter should be excluded.
        `Param.use_in_context()` provides further information.
      - flags: there are several flags that can be used to further tune the
        parameter behavior:
            * no_display (Output parameters only): do not display the parameter
            * no_create: do not include the parameter for crud.Create based
              commands
            * no_update: do not include the parameter for crud.update based
              commands
            * no_option: this attribute is not displayed in the CLI, usually
              because there's a better way of setting it (for example, a
              separate command)
            * virtual_attribute: the parameter is not stored physically in the
              LDAP and thus attribute `attribute` is not enabled
            * suppress_empty (Output parameters only): do not display parameter
              value when empty
            * ask_create: CLI asks for parameter value even when the parameter
              is not `required`. Applied for all crud.Create based commands
            * ask_update: CLI asks for parameter value even when the parameter
              is not `required`. Applied for all crud.Update based commands
            * req_update: The parameter is `required` in all crud.Update based
              commands
            * nonempty: This is an internal flag; a required attribute should
              be used instead of it.
              The value of this parameter must not be empty, but it may
              not be given at all. All crud.Update commands automatically
              convert required parameters to `nonempty` ones, so the value
              can be unspecified (unchanged) but cannot be deleted.
      - hint: this attribute is currently not used
      - alwaysask: when enabled, CLI asks for parameter value even when the
        parameter is not `required`
      - sortorder: used to sort a list of parameters for Command. See
        `Command.finalize()` for further information
      - csv: this multivalue attribute is given in CSV format
      - csv_separator: character that separates values in CSV (comma by
        default)
      - csv_skipspace: if true, leading whitespace will be ignored in
        individual CSV values
    """

    # This is a dummy type so that most of the functionality of Param can be
    # unit tested directly without always creating a subclass; however, a real
    # (direct) subclass must *always* override this class attribute:
    type = NoneType  # Ouch, this wont be very useful in the real world!

    # Subclasses should override this with something more specific:
    type_error = _('incorrect type')

    # _convert_scalar operates only on scalar values
    scalar_error = _('Only one value is allowed')

    kwargs = (
        ('cli_name', str, None),
        ('cli_short_name', str, None),
        ('label', (basestring, Gettext), None),
        ('doc', (basestring, Gettext), None),
        ('required', bool, True),
        ('multivalue', bool, False),
        ('primary_key', bool, False),
        ('normalizer', callable, None),
        ('default_from', DefaultFrom, None),
        ('autofill', bool, False),
        ('query', bool, False),
        ('attribute', bool, False),
        ('include', frozenset, None),
        ('exclude', frozenset, None),
        ('flags', frozenset, frozenset()),
        ('hint', (str, Gettext), None),
        ('alwaysask', bool, False),
        ('sortorder', int, 2), # see finalize()
        ('csv', bool, False),
        ('csv_separator', str, ','),
        ('csv_skipspace', bool, True),
        ('option_group', unicode, None),

        # The 'default' kwarg gets appended in Param.__init__():
        # ('default', self.type, None),
    )

    def __init__(self, name, *rules, **kw):
        # We keep these values to use in __repr__():
        self.param_spec = name
        self.__kw = dict(kw)

        if isinstance(self, Password):
            self.password = True
        else:
            self.password = False

        # Merge in kw from parse_param_spec():
        (name, kw_from_spec) = parse_param_spec(name)
        if not 'required' in kw:
            kw['required'] = kw_from_spec['required']
        if not 'multivalue' in kw:
            kw['multivalue'] = kw_from_spec['multivalue']
        self.name = check_name(name)
        self.nice = '%s(%r)' % (self.__class__.__name__, self.param_spec)

        # Add 'default' to self.kwargs and makes sure no unknown kw were given:
        assert type(self.type) is type
        if kw.get('multivalue', True):
            self.kwargs += (('default', tuple, None),)
        else:
            self.kwargs += (('default', self.type, None),)
        if not set(t[0] for t in self.kwargs).issuperset(self.__kw):
            extra = set(kw) - set(t[0] for t in self.kwargs)
            raise TypeError(
                '%s: takes no such kwargs: %s' % (self.nice,
                    ', '.join(repr(k) for k in sorted(extra))
                )
            )

        # Merge in default for 'cli_name', label, doc if not given:
        if kw.get('cli_name') is None:
            kw['cli_name'] = self.name

        if kw.get('label') is None:
            kw['label'] = FixMe(self.name)

        if kw.get('doc') is None:
            kw['doc'] = kw['label']

        # Wrap 'default_from' in a DefaultFrom if not already:
        df = kw.get('default_from', None)
        if callable(df) and not isinstance(df, DefaultFrom):
            kw['default_from'] = DefaultFrom(df)

        # We keep this copy with merged values also to use when cloning:
        self.__clonekw = kw

        # Perform type validation on kw, add in class rules:
        class_rules = []
        for (key, kind, default) in self.kwargs:
            value = kw.get(key, default)
            if value is not None:
                if kind is frozenset:
                    if type(value) in (list, tuple):
                        value = frozenset(value)
                    elif type(value) is str:
                        value = frozenset([value])
                if (
                    type(kind) is type and not isinstance(value, kind)
                    or
                    type(kind) is tuple and not isinstance(value, kind)
                ):
                    raise TypeError(
                        TYPE_ERROR % (key, kind, value, type(value))
                    )
                elif kind is callable and not callable(value):
                    raise TypeError(
                        CALLABLE_ERROR % (key, value, type(value))
                    )
            if hasattr(self, key):
                raise ValueError('kwarg %r conflicts with attribute on %s' % (
                    key, self.__class__.__name__)
                )
            setattr(self, key, value)
            rule_name = '_rule_%s' % key
            if value is not None and hasattr(self, rule_name):
                class_rules.append(getattr(self, rule_name))
        check_name(self.cli_name)

        # Check that only 'include' or 'exclude' was provided:
        if None not in (self.include, self.exclude):
            raise ValueError(
                '%s: cannot have both %s=%r and %s=%r' % (
                    self.nice,
                    'include', self.include,
                    'exclude', self.exclude,
                )
            )

        # Check that if csv is set, multivalue is set too
        if self.csv and not self.multivalue:
            raise ValueError('%s: cannot have csv without multivalue' % self.nice)

        # Check that all the rules are callable
        self.class_rules = tuple(class_rules)
        self.rules = rules
        if self.query:
            # by definition a query enforces no class or parameter rules
            self.all_rules = ()
        else:
            self.all_rules = self.class_rules + self.rules
        for rule in self.all_rules:
            if not callable(rule):
                raise TypeError(
                    '%s: rules must be callable; got %r' % (self.nice, rule)
                )

        # Check that cli_short_name is only 1 character long:
        if not (self.cli_short_name is None or len(self.cli_short_name) == 1):
            raise ValueError(
                '%s: cli_short_name can only be a single character: %s' % (
                    self.nice, self.cli_short_name)
            )

        # And we're done.
        lock(self)

    def __repr__(self):
        """
        Return an expresion that could construct this `Param` instance.
        """
        return '%s(%s)' % (
            self.__class__.__name__,
            ', '.join(self.__repr_iter())
        )

    def __repr_iter(self):
        yield repr(self.param_spec)
        for rule in self.rules:
            yield rule.__name__
        for key in sorted(self.__kw):
            value = self.__kw[key]
            if callable(value) and hasattr(value, '__name__'):
                value = value.__name__
            else:
                value = repr(value)
            yield '%s=%s' % (key, value)

    def __call__(self, value, **kw):
        """
        One stop shopping.
        """
        if value in NULLS:
            value = self.get_default(**kw)
        else:
            value = self.convert(self.normalize(value))
        if hasattr(self, 'env'):
            self.validate(value, self.env.context, supplied=self.name in kw)  #pylint: disable=E1101
        else:
            self.validate(value, supplied=self.name in kw)
        return value

    def get_param_name(self):
        """
        Return the right name of an attribute depending on usage.

        Normally errors should use cli_name, our "friendly" name. When
        using the API directly or *attr return the real name.
        """
        name = self.cli_name
        if not name:
            name = self.name
        return name

    def kw(self):
        """
        Iterate through ``(key,value)`` for all kwargs passed to constructor.
        """
        for key in sorted(self.__kw):
            value = self.__kw[key]
            if callable(value) and hasattr(value, '__name__'):
                value = value.__name__
            yield (key, value)

    def use_in_context(self, env):
        """
        Return ``True`` if this parameter should be used in ``env.context``.

        If a parameter is created with niether the ``include`` nor the
        ``exclude`` kwarg, this method will always return ``True``.  For
        example:

        >>> from ipalib.config import Env
        >>> param = Param('my_param')
        >>> param.use_in_context(Env(context='foo'))
        True
        >>> param.use_in_context(Env(context='bar'))
        True

        If a parameter is created with an ``include`` kwarg, this method will
        only return ``True`` if ``env.context`` is in ``include``.  For example:

        >>> param = Param('my_param', include=['foo', 'whatever'])
        >>> param.include
        frozenset(['foo', 'whatever'])
        >>> param.use_in_context(Env(context='foo'))
        True
        >>> param.use_in_context(Env(context='bar'))
        False

        If a paremeter is created with an ``exclude`` kwarg, this method will
        only return ``True`` if ``env.context`` is not in ``exclude``.  For
        example:

        >>> param = Param('my_param', exclude=['foo', 'whatever'])
        >>> param.exclude
        frozenset(['foo', 'whatever'])
        >>> param.use_in_context(Env(context='foo'))
        False
        >>> param.use_in_context(Env(context='bar'))
        True

        Note that the ``include`` and ``exclude`` kwargs are mutually exclusive
        and that at most one can be suppelied to `Param.__init__()`.  For
        example:

        >>> param = Param('nope', include=['foo'], exclude=['bar'])
        Traceback (most recent call last):
          ...
        ValueError: Param('nope'): cannot have both include=frozenset(['foo']) and exclude=frozenset(['bar'])

        So that subclasses can add additional logic based on other environment
        variables, the entire `config.Env` instance is passed in rather than
        just the value of ``env.context``.
        """
        if self.include is not None:
            return (env.context in self.include)
        if self.exclude is not None:
            return (env.context not in self.exclude)
        return True

    def safe_value(self, value):
        """
        Return a value safe for logging.

        This is used so that passwords don't get logged.  If this is a
        `Password` instance and ``value`` is not ``None``, a constant
        ``u'********'`` is returned.  For example:

        >>> p = Password('my_password')
        >>> p.safe_value(u'This is my password')
        u'********'
        >>> p.safe_value(None) is None
        True

        If this is not a `Password` instance, ``value`` is returned unchanged.
        For example:

        >>> s = Str('my_str')
        >>> s.safe_value(u'Some arbitrary value')
        u'Some arbitrary value'
        """
        if self.password and value is not None:
            return u'********'
        return value

    def clone(self, **overrides):
        """
        Return a new `Param` instance similar to this one.
        """
        return self.clone_rename(self.name, **overrides)

    def clone_rename(self, name, **overrides):
        """
        Return a new `Param` instance similar to this one, but named differently
        """
        return self.clone_retype(name, self.__class__, **overrides)

    def clone_retype(self, name, klass, **overrides):
        """
        Return a new `Param` instance similar to this one, but of a different type
        """
        kw = dict(self.__clonekw)
        kw.update(overrides)
        return klass(name, *self.rules, **kw)

    # The following 2 functions were taken from the Python
    # documentation at http://docs.python.org/library/csv.html
    def __utf_8_encoder(self, unicode_csv_data):
        for line in unicode_csv_data:
            yield line.encode('utf-8')

    def __unicode_csv_reader(self, unicode_csv_data, dialect=csv.excel, **kwargs):
        # csv.py doesn't do Unicode; encode temporarily as UTF-8:
        csv_reader = csv.reader(self.__utf_8_encoder(unicode_csv_data),
                                dialect=dialect,
                                delimiter=self.csv_separator, quotechar='"',
                                skipinitialspace=self.csv_skipspace,
                                **kwargs)
        for row in csv_reader:
            # decode UTF-8 back to Unicode, cell by cell:
            yield [unicode(cell, 'utf-8') for cell in row]

    def split_csv(self, value):
        """Split CSV strings into individual values.

        For CSV params, ``value`` is a tuple of strings. Each of these is split
        on commas, and the results are concatenated into one tuple.

        For example::

            >>> param = Param('telephones', multivalue=True, csv=True)
            >>> param.split_csv((u'1, 2', u'3', u'4, 5, 6'))
            (u'1', u'2', u'3', u'4', u'5', u'6')

        If ``value`` is not a tuple (or list), it is only split::

            >>> param = Param('telephones', multivalue=True, csv=True)
            >>> param.split_csv(u'1, 2, 3')
            (u'1', u'2', u'3')

        For non-CSV params, return the value unchanged.
        """
        if self.csv:
            if type(value) not in (tuple, list):
                value = (value,)
            newval = []
            for v in value:
                if isinstance(v, basestring):
                    lines = unicode(v).splitlines()
                    for row in self.__unicode_csv_reader(lines):
                        newval.extend(row)
                else:
                    newval.append(v)
            return tuple(newval)
        else:
            return value

    def normalize(self, value):
        """
        Normalize ``value`` using normalizer callback.

        For example:

        >>> param = Param('telephone',
        ...     normalizer=lambda value: value.replace('.', '-')
        ... )
        >>> param.normalize(u'800.123.4567')
        u'800-123-4567'

        If this `Param` instance was created with a normalizer callback and
        ``value`` is a unicode instance, the normalizer callback is called and
        *its* return value is returned.

        On the other hand, if this `Param` instance was *not* created with a
        normalizer callback, if ``value`` is *not* a unicode instance, or if an
        exception is caught when calling the normalizer callback, ``value`` is
        returned unchanged.

        :param value: A proposed value for this parameter.
        """
        if self.multivalue:
            if type(value) not in (tuple, list):
                value = (value,)
        if self.multivalue:
            return tuple(
                self._normalize_scalar(v) for v in value
            )
        else:
            return self._normalize_scalar(value)

    def _normalize_scalar(self, value):
        """
        Normalize a scalar value.

        This method is called once for each value in a multivalue.
        """
        if type(value) is not unicode:
            return value
        if self.normalizer is None:
            return value
        try:
            return self.normalizer(value)
        except StandardError:
            return value

    def convert(self, value):
        """
        Convert ``value`` to the Python type required by this parameter.

        For example:

        >>> scalar = Str('my_scalar')
        >>> scalar.type
        <type 'unicode'>
        >>> scalar.convert(43.2)
        u'43.2'

        (Note that `Str` is a subclass of `Param`.)

        All values in `constants.NULLS` will be converted to ``None``.  For
        example:

        >>> scalar.convert(u'') is None  # An empty string
        True
        >>> scalar.convert([]) is None  # An empty list
        True

        Likewise, values in `constants.NULLS` will be filtered out of a
        multivalue parameter.  For example:

        >>> multi = Str('my_multi', multivalue=True)
        >>> multi.convert([1.5, '', 17, None, u'Hello'])
        (u'1.5', u'17', u'Hello')
        >>> multi.convert([None, u'']) is None  # Filters to an empty list
        True

        Lastly, multivalue parameters will always return a ``tuple`` (assuming
        they don't return ``None`` as in the last example above).  For example:

        >>> multi.convert(42)  # Called with a scalar value
        (u'42',)
        >>> multi.convert([0, 1])  # Called with a list value
        (u'0', u'1')

        Note that how values are converted (and from what types they will be
        converted) completely depends upon how a subclass implements its
        `Param._convert_scalar()` method.  For example, see
        `Str._convert_scalar()`.

        :param value: A proposed value for this parameter.
        """
        if value in NULLS:
            return
        if self.multivalue:
            if type(value) not in (tuple, list):
                value = (value,)
            values = tuple(
                self._convert_scalar(v, i) for (i, v) in filter(
                    lambda iv: iv[1] not in NULLS, enumerate(value)
                )
            )
            if len(values) == 0:
                return
            return values
        return self._convert_scalar(value)

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) is self.type:
            return value
        raise ConversionError(name=self.name, index=index,
            error=ugettext(self.type_error),
        )

    def validate(self, value, context=None, supplied=None):
        """
        Check validity of ``value``.

        :param value: A proposed value for this parameter.
        :param context: The context we are running in.
        :param supplied: True if this parameter was supplied explicitly.
        """
        if value is None:
            if self.required or (supplied and 'nonempty' in self.flags):
                if context == 'cli':
                    raise RequirementError(name=self.cli_name)
                else:
                    raise RequirementError(name=self.name)
            return
        if self.multivalue:
            if type(value) is not tuple:
                raise TypeError(
                    TYPE_ERROR % ('value', tuple, value, type(value))
                )
            if len(value) < 1:
                raise ValueError('value: empty tuple must be converted to None')
            for (i, v) in enumerate(value):
                self._validate_scalar(v, i)
        else:
            self._validate_scalar(value)

    def _validate_scalar(self, value, index=None):
        if type(value) is not self.type:
            raise ValidationError(name=self.name,
                error='need a %r; got %r (a %r)' % (
                    self.type, value, type(value)
                )
            )
        if index is not None and type(index) is not int:
            raise TypeError(
                TYPE_ERROR % ('index', int, index, type(index))
            )
        for rule in self.all_rules:
            error = rule(ugettext, value)
            if error is not None:
                raise ValidationError(
                    name=self.get_param_name(),
                    value=value,
                    index=index,
                    error=error,
                    rule=rule,
                )

    def get_default(self, **kw):
        """
        Return the static default or construct and return a dynamic default.

        (In these examples, we will use the `Str` and `Bytes` classes, which
        both subclass from `Param`.)

        The *default* static default is ``None``.  For example:

        >>> s = Str('my_str')
        >>> s.default is None
        True
        >>> s.get_default() is None
        True

        However, you can provide your own static default via the ``default``
        keyword argument when you create your `Param` instance.  For example:

        >>> s = Str('my_str', default=u'My Static Default')
        >>> s.default
        u'My Static Default'
        >>> s.get_default()
        u'My Static Default'

        If you need to generate a dynamic default from other supplied parameter
        values, provide a callback via the ``default_from`` keyword argument.
        This callback will be automatically wrapped in a `DefaultFrom` instance
        if it isn't one already (see the `DefaultFrom` class for all the gory
        details).  For example:

        >>> login = Str('login', default=u'my-static-login-default',
        ...     default_from=lambda first, last: (first[0] + last).lower(),
        ... )
        >>> isinstance(login.default_from, DefaultFrom)
        True
        >>> login.default_from.keys
        ('first', 'last')

        Then when all the keys needed by the `DefaultFrom` instance are present,
        the dynamic default is constructed and returned.  For example:

        >>> kw = dict(last=u'Doe', first=u'John')
        >>> login.get_default(**kw)
        u'jdoe'

        Or if any keys are missing, your *static* default is returned.
        For example:

        >>> kw = dict(first=u'John', department=u'Engineering')
        >>> login.get_default(**kw)
        u'my-static-login-default'
        """
        if self.default_from is not None:
            default = self.default_from(**kw)
            if default is not None:
                try:
                    return self.convert(self.normalize(default))
                except StandardError:
                    pass
        return self.default

    json_exclude_attrs = (
        'alwaysask', 'autofill', 'cli_name', 'cli_short_name', 'csv',
        'csv_separator', 'csv_skipspace', 'sortorder', 'falsehoods', 'truths',
        'version',
    )

    def __json__(self):
        json_dict = {}
        for (a, k, d) in self.kwargs:
            if a in self.json_exclude_attrs:
                continue
            if k in (callable, DefaultFrom):
                continue
            elif isinstance(getattr(self, a), frozenset):
                json_dict[a] = [k for k in getattr(self, a, [])]
            else:
                val = getattr(self, a, '')
                if val is None or not val:
                    # ignore false and not set because lack of their presence is
                    # the information itself
                    continue;
                json_dict[a] = val
        json_dict['class'] = self.__class__.__name__
        json_dict['name'] = self.name
        json_dict['type'] = self.type.__name__
        return json_dict


class Bool(Param):
    """
    A parameter for boolean values (stored in the ``bool`` type).
    """

    type = bool
    type_error = _('must be True or False')

    # FIXME: This my quick hack to get some UI stuff working, change these defaults
    #   --jderose 2009-08-28
    kwargs = Param.kwargs + (
        ('truths', frozenset, frozenset([1, u'1', True, u'true', u'TRUE'])),
        ('falsehoods', frozenset, frozenset([0, u'0', False, u'false', u'FALSE'])),
    )

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) is self.type:
            return value
        if isinstance(value, basestring):
            value = value.lower()
        if value in self.truths:
            return True
        if value in self.falsehoods:
            return False
        if type(value) in (tuple, list):
            raise ConversionError(name=self.name, index=index,
            error=ugettext(self.scalar_error))
        raise ConversionError(name=self.name, index=index,
            error=ugettext(self.type_error),
        )


class Flag(Bool):
    """
    A boolean parameter that always gets filled in with a default value.

    This `Bool` subclass forces ``autofill=True`` in `Flag.__init__()`.  If no
    default is provided, it also fills in a default value of ``False``.
    Lastly, unlike the `Bool` class, the default must be either ``True`` or
    ``False`` and cannot be ``None``.

    For example:

    >>> flag = Flag('my_flag')
    >>> (flag.autofill, flag.default)
    (True, False)

    To have a default value of ``True``, create your `Flag` intance with
    ``default=True``.  For example:

    >>> flag = Flag('my_flag', default=True)
    >>> (flag.autofill, flag.default)
    (True, True)

    Also note that creating a `Flag` instance with ``autofill=False`` will have
    no effect.  For example:

    >>> flag = Flag('my_flag', autofill=False)
    >>> flag.autofill
    True
    """

    def __init__(self, name, *rules, **kw):
        kw['autofill'] = True
        if 'default' not in kw:
            kw['default'] = False
        if type(kw['default']) is not bool:
            default = kw['default']
            raise TypeError(
                TYPE_ERROR % ('default', bool, default, type(default))
            )
        super(Flag, self).__init__(name, *rules, **kw)


class Number(Param):
    """
    Base class for the `Int` and `Decimal` parameters.
    """

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) is self.type:
            return value
        if type(value) in (unicode, int, float):
            try:
                return self.type(value)
            except ValueError:
                pass
        if type(value) in (tuple, list):
            raise ConversionError(name=self.name, index=index,
            error=ugettext(self.scalar_error))
        raise ConversionError(name=self.name, index=index,
            error=ugettext(self.type_error),
        )


class Int(Number):
    """
    A parameter for integer values (stored in the ``int`` type).
    """

    type = int
    type_error = _('must be an integer')

    kwargs = Param.kwargs + (
        ('minvalue', int, int(MININT)),
        ('maxvalue', int, int(MAXINT)),
    )

    def __init__(self, name, *rules, **kw):
        #pylint: disable=E1003
        super(Number, self).__init__(name, *rules, **kw)

        if (self.minvalue > self.maxvalue) and (self.minvalue is not None and self.maxvalue is not None):
            raise ValueError(
                '%s: minvalue > maxvalue (minvalue=%r, maxvalue=%r)' % (
                    self.nice, self.minvalue, self.maxvalue)
            )

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) in (int, long):
            return value
        if type(value) is unicode:
            # permit floating point strings
            if value.find(u'.') >= 0:
                try:
                    return int(float(value))
                except ValueError:
                    pass
            else:
                try:
                    # 2nd arg is radix base, 2nd arg only accepted for strings.
                    # Zero means determine radix base from prefix (e.g. 0x for hex)
                    return int(value, 0)
                except ValueError:
                    pass
        if type(value) is float:
            try:
                return int(value)
            except ValueError:
                pass
        raise ConversionError(name=self.get_param_name(), index=index,
            error=ugettext(self.type_error),
        )

    def _rule_minvalue(self, _, value):
        """
        Check min constraint.
        """
        assert type(value) in (int, long)
        if value < self.minvalue or value < MININT:
            return _('must be at least %(minvalue)d') % dict(
                minvalue=self.minvalue,
            )

    def _rule_maxvalue(self, _, value):
        """
        Check max constraint.
        """
        assert type(value) in (int, long)
        if value > self.maxvalue or value > MAXINT:
            return _('can be at most %(maxvalue)d') % dict(
                maxvalue=self.maxvalue,
            )

    def _validate_scalar(self, value, index=None):
        """
        This duplicates _validate_scalar in the Param class with
        the exception that it allows both int and long types. The
        min/max rules handle size enforcement.
        """
        if type(value)  not in (int, long):
            raise ValidationError(name=self.name,
                error='need a %r; got %r (a %r)' % (
                    self.type, value, type(value)
                )
            )
        if index is not None and type(index) is not int:
            raise TypeError(
                TYPE_ERROR % ('index', int, index, type(index))
            )
        for rule in self.all_rules:
            error = rule(ugettext, value)
            if error is not None:
                raise ValidationError(
                    name=self.get_param_name(),
                    value=value,
                    index=index,
                    error=error,
                    rule=rule,
                )


class Decimal(Number):
    """
    A parameter for floating-point values (stored in the ``Decimal`` type).

    Python Decimal type helps overcome problems tied to plain "float" type,
    e.g. problem with representation or value comparison. In order to safely
    transfer the value over RPC libraries, it is being converted to string
    which is then converted back to Decimal number.
    """

    type = decimal.Decimal
    type_error = _('must be a decimal number')

    kwargs = Param.kwargs + (
        ('minvalue', decimal.Decimal, None),
        ('maxvalue', decimal.Decimal, None),
        # round Decimal to given precision
        ('precision', int, None),
        # when False, number is normalized to non-exponential form
        ('exponential', bool, False),
        # set of allowed decimal number classes
        ('numberclass', tuple, ('-Normal', '+Zero', '+Normal')),
    )

    def __init__(self, name, *rules, **kw):
        for kwparam in ('minvalue', 'maxvalue', 'default'):
            value = kw.get(kwparam)
            if value is None:
                continue
            if isinstance(value, (basestring, float)):
                try:
                    value = decimal.Decimal(value)
                except Exception, e:
                    raise ValueError(
                       '%s: cannot parse kwarg %s: %s' % (
                        name, kwparam, str(e)))
                kw[kwparam] = value

        super(Decimal, self).__init__(name, *rules, **kw)

        if (self.minvalue > self.maxvalue) \
            and (self.minvalue is not None and \
                 self.maxvalue is not None):
            raise ValueError(
                '%s: minvalue > maxvalue (minvalue=%s, maxvalue=%s)' % (
                    self.nice, self.minvalue, self.maxvalue)
            )

        if self.precision is not None and self.precision < 0:
            raise ValueError('%s: precision must be at least 0' % self.nice)

    def _rule_minvalue(self, _, value):
        """
        Check min constraint.
        """
        assert type(value) is decimal.Decimal
        if value < self.minvalue:
            return _('must be at least %(minvalue)s') % dict(
                minvalue=self.minvalue,
            )

    def _rule_maxvalue(self, _, value):
        """
        Check max constraint.
        """
        assert type(value) is decimal.Decimal
        if value > self.maxvalue:
            return _('can be at most %(maxvalue)s') % dict(
                maxvalue=self.maxvalue,
            )

    def _enforce_numberclass(self, value):
        #pylint: disable=E1101
        numberclass = value.number_class()
        if numberclass not in self.numberclass:
            raise ValidationError(name=self.get_param_name(),
                    error=_("number class '%(cls)s' is not included in a list "
                            "of allowed number classes: %(allowed)s") \
                            % dict(cls=numberclass,
                                   allowed=u', '.join(self.numberclass))
                )

    def _enforce_precision(self, value):
        assert type(value) is decimal.Decimal
        if self.precision is not None:
            quantize_exp = decimal.Decimal(10) ** -self.precision
            try:
                value = value.quantize(quantize_exp)
            except decimal.DecimalException, e:
                raise ConversionError(name=self.get_param_name(),
                                      error=unicode(e))
        return value

    def _remove_exponent(self, value):
        assert type(value) is decimal.Decimal

        if not self.exponential: #pylint: disable=E1101
            try:
                # adopted from http://docs.python.org/library/decimal.html
                value = value.quantize(decimal.Decimal(1)) \
                        if value == value.to_integral() \
                        else value.normalize()
            except decimal.DecimalException, e:
                raise ConversionError(name=self.get_param_name(),
                                      error=unicode(e))

        return value

    def _test_and_normalize(self, value):
        """
        This method is run in conversion and normalization methods to test
        that the Decimal number conforms to Parameter boundaries and then
        normalizes the value.
        """
        self._enforce_numberclass(value)
        value = self._remove_exponent(value)
        value = self._enforce_precision(value)
        return value

    def _convert_scalar(self, value, index=None):
        if isinstance(value, (basestring, float)):
            try:
                value = decimal.Decimal(value)
            except decimal.DecimalException, e:
                raise ConversionError(name=self.get_param_name(), index=index,
                                      error=unicode(e))

        if isinstance(value, decimal.Decimal):
            return self._test_and_normalize(value)

        return super(Decimal, self)._convert_scalar(value, index)

    def _normalize_scalar(self, value):
        if isinstance(value, decimal.Decimal):
            return self._test_and_normalize(value)

        return super(Decimal, self)._normalize_scalar(value)

class Data(Param):
    """
    Base class for the `Bytes` and `Str` parameters.

    Previously `Str` was as subclass of `Bytes`.  Now the common functionality
    has been split into this base class so that ``isinstance(foo, Bytes)`` wont
    be ``True`` when ``foo`` is actually an `Str` instance (which is confusing).
    """

    kwargs = Param.kwargs + (
        ('minlength', int, None),
        ('maxlength', int, None),
        ('length', int, None),
        ('pattern', (basestring,), None),
        ('pattern_errmsg', (basestring,), None),
    )

    re = None
    re_errmsg = None

    def __init__(self, name, *rules, **kw):
        super(Data, self).__init__(name, *rules, **kw)

        if not (
            self.length is None or
            (self.minlength is None and self.maxlength is None)
        ):
            raise ValueError(
                '%s: cannot mix length with minlength or maxlength' % self.nice
            )

        if self.minlength is not None and self.minlength < 1:
            raise ValueError(
                '%s: minlength must be >= 1; got %r' % (self.nice, self.minlength)
            )

        if self.maxlength is not None and self.maxlength < 1:
            raise ValueError(
                '%s: maxlength must be >= 1; got %r' % (self.nice, self.maxlength)
            )

        if None not in (self.minlength, self.maxlength):
            if self.minlength > self.maxlength:
                raise ValueError(
                    '%s: minlength > maxlength (minlength=%r, maxlength=%r)' % (
                        self.nice, self.minlength, self.maxlength)
                )
            elif self.minlength == self.maxlength:
                raise ValueError(
                    '%s: minlength == maxlength; use length=%d instead' % (
                        self.nice, self.minlength)
                )

    def _rule_pattern(self, _, value):
        """
        Check pattern (regex) contraint.
        """
        assert type(value) is self.type
        if self.re.match(value) is None:
            if self.re_errmsg:
                return self.re_errmsg % dict(pattern=self.pattern,)
            else:
                return _('must match pattern "%(pattern)s"') % dict(
                    pattern=self.pattern,
                )


class Bytes(Data):
    """
    A parameter for binary data (stored in the ``str`` type).

    This class is named *Bytes* instead of *Str* so it's aligned with the
    Python v3 ``(str, unicode) => (bytes, str)`` clean-up.  See:

        http://docs.python.org/3.0/whatsnew/3.0.html

    Also see the `Str` parameter.
    """

    type = str
    type_error = _('must be binary data')

    def __init__(self, name, *rules, **kw):
        if kw.get('pattern', None) is None:
            self.re = None
        else:
            self.re = re.compile(kw['pattern'])
        self.re_errmsg = kw.get('pattern_errmsg', None)
        super(Bytes, self).__init__(name, *rules, **kw)

    def _rule_minlength(self, _, value):
        """
        Check minlength constraint.
        """
        assert type(value) is str
        if len(value) < self.minlength:
            return _('must be at least %(minlength)d bytes') % dict(
                minlength=self.minlength,
            )

    def _rule_maxlength(self, _, value):
        """
        Check maxlength constraint.
        """
        assert type(value) is str
        if len(value) > self.maxlength:
            return _('can be at most %(maxlength)d bytes') % dict(
                maxlength=self.maxlength,
            )

    def _rule_length(self, _, value):
        """
        Check length constraint.
        """
        assert type(value) is str
        if len(value) != self.length:
            return _('must be exactly %(length)d bytes') % dict(
                length=self.length,
            )

    def _convert_scalar(self, value, index=None):
        if isinstance(value, unicode):
            try:
                value = base64.b64decode(value)
            except TypeError, e:
                raise Base64DecodeError(reason=str(e))
        return super(Bytes, self)._convert_scalar(value, index)


class Str(Data):
    """
    A parameter for Unicode text (stored in the ``unicode`` type).

    This class is named *Str* instead of *Unicode* so it's aligned with the
    Python v3 ``(str, unicode) => (bytes, str)`` clean-up.  See:

        http://docs.python.org/3.0/whatsnew/3.0.html

    Also see the `Bytes` parameter.
    """

    kwargs = Data.kwargs + (
        ('noextrawhitespace', bool, True),
    )

    type = unicode
    type_error = _('must be Unicode text')

    def __init__(self, name, *rules, **kw):
        if kw.get('pattern', None) is None:
            self.re = None
        else:
            self.re = re.compile(kw['pattern'], re.UNICODE)
        self.re_errmsg = kw.get('pattern_errmsg', None)
        super(Str, self).__init__(name, *rules, **kw)

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) is self.type:
            return value
        if type(value) in (int, float, decimal.Decimal):
            return self.type(value)
        if type(value) in (tuple, list):
            raise ConversionError(name=self.name, index=index,
            error=ugettext(self.scalar_error))
        raise ConversionError(name=self.name, index=index,
            error=ugettext(self.type_error),
        )

    def _rule_noextrawhitespace(self, _, value):
        """
        Do not allow leading/trailing spaces.
        """
        assert type(value) is unicode
        if self.noextrawhitespace is False: #pylint: disable=E1101
            return
        if len(value) != len(value.strip()):
            return _('Leading and trailing spaces are not allowed')

    def _rule_minlength(self, _, value):
        """
        Check minlength constraint.
        """
        assert type(value) is unicode
        if len(value) < self.minlength:
            return _('must be at least %(minlength)d characters') % dict(
                minlength=self.minlength,
            )

    def _rule_maxlength(self, _, value):
        """
        Check maxlength constraint.
        """
        assert type(value) is unicode
        if len(value) > self.maxlength:
            return _('can be at most %(maxlength)d characters') % dict(
                maxlength=self.maxlength,
            )

    def _rule_length(self, _, value):
        """
        Check length constraint.
        """
        assert type(value) is unicode
        if len(value) != self.length:
            return _('must be exactly %(length)d characters') % dict(
                length=self.length,
            )


class IA5Str(Str):
    """
    An IA5String per RFC 4517
    """

    def __init__(self, name, *rules, **kw):
        super(IA5Str, self).__init__(name, *rules, **kw)

    def _convert_scalar(self, value, index=None):
        if isinstance(value, basestring):
            for i in xrange(len(value)):
                if ord(value[i]) > 127:
                    raise ConversionError(name=self.get_param_name(),
                        index=index,
                        error=_('The character \'%(char)r\' is not allowed.') %
                            dict(char=value[i],)
                    )
        return super(IA5Str, self)._convert_scalar(value, index)


class Password(Str):
    """
    A parameter for passwords (stored in the ``unicode`` type).
    """

    kwargs = Str.kwargs + (
        ('confirm', bool, True),
    )

    def _convert_scalar(self, value, index=None):
        if isinstance(value, (tuple, list)) and len(value) == 2:
            (p1, p2) = value
            if p1 != p2:
                raise PasswordMismatch(name=self.name, index=index)
            value = p1
        return super(Password, self)._convert_scalar(value, index)


class Enum(Param):
    """
    Base class for parameters with enumerable values.
    """

    kwargs = Param.kwargs + (
        ('values', tuple, tuple()),
    )

    def __init__(self, name, *rules, **kw):
        super(Enum, self).__init__(name, *rules, **kw)
        for (i, v) in enumerate(self.values):
            if type(v) is not self.type:
                n = '%s values[%d]' % (self.nice, i)
                raise TypeError(
                    TYPE_ERROR % (n, self.type, v, type(v))
                )

    def _rule_values(self, _, value, **kw):
        if value not in self.values:
            return _('must be one of %(values)r') % dict(
                values=self.values,
            )


class BytesEnum(Enum):
    """
    Enumerable for binary data (stored in the ``str`` type).
    """

    type = unicode


class StrEnum(Enum):
    """
    Enumerable for Unicode text (stored in the ``unicode`` type).

    For example:

    >>> enum = StrEnum('my_enum', values=(u'One', u'Two', u'Three'))
    >>> enum.validate(u'Two', 'cli') is None
    True
    >>> enum.validate(u'Four', 'cli')
    Traceback (most recent call last):
      ...
    ValidationError: invalid 'my_enum': must be one of (u'One', u'Two', u'Three')
    """

    type = unicode


class Any(Param):
    """
    A parameter capable of holding values of any type. For internal use only.
    """

    type = object

    def _convert_scalar(self, value, index=None):
        return value

    def _validate_scalar(self, value, index=None):
        for rule in self.all_rules:
            error = rule(ugettext, value)
            if error is not None:
                raise ValidationError(
                    name=self.name,
                    value=value,
                    index=index,
                    error=error,
                    rule=rule,
                )


class File(Str):
    """
    File parameter type.

    Accepts file names and loads their content into the parameter value.
    """
    kwargs = Data.kwargs + (
        # valid for CLI, other backends (e.g. webUI) can ignore this
        ('stdin_if_missing', bool, False),
        ('noextrawhitespace', bool, False),
    )


class AccessTime(Str):
    """
    Access time parameter type.

    Accepts values conforming to generalizedTime as defined in RFC 4517
    section 3.3.13 without time zone information.
    """
    def _check_HHMM(self, t):
        if len(t) != 4:
            raise ValueError('HHMM must be exactly 4 characters long')
        if not t.isnumeric():
            raise ValueError('HHMM non-numeric')
        hh = int(t[0:2])
        if hh < 0 or hh > 23:
            raise ValueError('HH out of range')
        mm = int(t[2:4])
        if mm < 0 or mm > 59:
            raise ValueError('MM out of range')

    def _check_dotw(self, t):
        if t.isnumeric():
            value = int(t)
            if value < 1 or value > 7:
                raise ValueError('day of the week out of range')
        elif t not in ('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'):
            raise ValueError('invalid day of the week')

    def _check_dotm(self, t, month_num=1, year=4):
        if not t.isnumeric():
            raise ValueError('day of the month non-numeric')
        value = int(t)
        if month_num in (1, 3, 5, 7, 8, 10, 12):
            if value < 1 or value > 31:
                raise ValueError('day of the month out of range')
        elif month_num in (4, 6, 9, 11):
            if value < 1 or value > 30:
                raise ValueError('day of the month out of range')
        elif month_num == 2:
            if year % 4 == 0 and (year % 100 != 0 or year % 400 == 0):
                if value < 1 or value > 29:
                    raise ValueError('day of the month out of range')
            else:
                if value < 1 or value > 28:
                    raise ValueError('day of the month out of range')

    def _check_wotm(self, t):
        if not t.isnumeric():
            raise ValueError('week of the month non-numeric')
        value = int(t)
        if value < 1 or value > 6:
            raise ValueError('week of the month out of range')

    def _check_woty(self, t):
        if not t.isnumeric():
            raise ValueError('week of the year non-numeric')
        value = int(t)
        if value < 1 or value > 52:
            raise ValueError('week of the year out of range')

    def _check_doty(self, t):
        if not t.isnumeric():
            raise ValueError('day of the year non-numeric')
        value = int(t)
        if value < 1 or value > 365:
            raise ValueError('day of the year out of range')

    def _check_month_num(self, t):
        if not t.isnumeric():
            raise ValueError('month number non-numeric')
        value = int(t)
        if value < 1 or value > 12:
            raise ValueError('month number out of range')

    def _check_interval(self, t, check_func):
        intervals = t.split(',')
        for i in intervals:
            if not i:
                raise ValueError('invalid time range')
            values = i.split('-')
            if len(values) > 2:
                raise ValueError('invalid time range')
            for v in values:
                check_func(v)
            if len(values) == 2:
                if int(values[0]) > int(values[1]):
                    raise ValueError('invalid time range')

    def _check_W_spec(self, ts, index):
        if ts[index] != 'day':
            raise ValueError('invalid week specifier')
        index += 1
        self._check_interval(ts[index], self._check_dotw)
        return index

    def _check_M_spec(self, ts, index):
        if ts[index] == 'week':
            self._check_interval(ts[index + 1], self._check_wotm)
            index = self._check_W_spec(ts, index + 2)
        elif ts[index] == 'day':
            index += 1
            self._check_interval(ts[index], self._check_dotm)
        else:
            raise ValueError('invalid month specifier')
        return index

    def _check_Y_spec(self, ts, index):
        if ts[index] == 'month':
            index += 1
            self._check_interval(ts[index], self._check_month_num)
            month_num = int(ts[index])
            index = self._check_M_spec(ts, index + 1)
        elif ts[index] == 'week':
            self._check_interval(ts[index + 1], self._check_woty)
            index = self._check_W_spec(ts, index + 2)
        elif ts[index] == 'day':
            index += 1
            self._check_interval(ts[index], self._check_doty)
        else:
            raise ValueError('invalid year specifier')
        return index

    def _check_generalized(self, t):
        assert type(t) is unicode
        if len(t) not in (10, 12, 14):
            raise ValueError('incomplete generalized time')
        if not t.isnumeric():
            raise ValueError('time non-numeric')
        # don't check year value, with time travel and all :)
        self._check_month_num(t[4:6])
        year_num = int(t[0:4])
        month_num = int(t[4:6])
        self._check_dotm(t[6:8], month_num, year_num)
        if len(t) >= 12:
            self._check_HHMM(t[8:12])
        else:
            self._check_HHMM('%s00' % t[8:10])
        if len(t) == 14:
            s = int(t[12:14])
            if s < 0 or s > 60:
                raise ValueError('seconds out of range')

    def _check(self, time):
        ts = time.split()
        if ts[0] == 'absolute':
            if len(ts) != 4:
                raise ValueError('invalid format, must be \'absolute generalizedTime ~ generalizedTime\'')
            self._check_generalized(ts[1])
            if ts[2] != '~':
                raise ValueError('invalid time range separator')
            self._check_generalized(ts[3])
            if int(ts[1]) >= int(ts[3]):
                raise ValueError('invalid time range')
        elif ts[0] == 'periodic':
            index = None
            if ts[1] == 'yearly':
                index = self._check_Y_spec(ts, 2)
            elif ts[1] == 'monthly':
                index = self._check_M_spec(ts, 2)
            elif ts[1] == 'weekly':
                index = self._check_W_spec(ts, 2)
            elif ts[1] == 'daily':
                index = 1
            if index is None:
                raise ValueError('period must be yearly, monthy or daily, got \'%s\'' % ts[1])
            self._check_interval(ts[index + 1], self._check_HHMM)
        else:
            raise ValueError('time neither absolute or periodic')

    def _rule_required(self, _, value):
        try:
            self._check(value)
        except ValueError, e:
            raise ValidationError(name=self.get_param_name(), error=e.args[0])
        except IndexError:
            raise ValidationError(
                name=self.get_param_name(), error=ugettext('incomplete time value')
            )
        return None


class DNParam(Param):
    type = DN

    def _convert_scalar(self, value, index=None):
        """
        Convert a single scalar value.
        """
        if type(value) is self.type:
            return value

        try:
            dn = DN(value)
        except Exception, e:
            raise ConversionError(name=self.get_param_name(), index=index,
                                  error=ugettext(e))
        return dn

def create_param(spec):
    """
    Create an `Str` instance from the shorthand ``spec``.

    This function allows you to create `Str` parameters (the most common) from
    a convenient shorthand that defines the parameter name, whether it is
    required, and whether it is multivalue.  (For the definition of the
    shorthand syntax, see the `parse_param_spec()` function.)

    If ``spec`` is an ``str`` instance, it will be used to create a new `Str`
    parameter, which will be returned.  For example:

    >>> s = create_param('hometown?')
    >>> s
    Str('hometown?')
    >>> (s.name, s.required, s.multivalue)
    ('hometown', False, False)

    On the other hand, if ``spec`` is already a `Param` instance, it is
    returned unchanged.  For example:

    >>> b = Bytes('cert')
    >>> create_param(b) is b
    True

    As a plugin author, you will not call this function directly (which would
    be no more convenient than simply creating the `Str` instance).  Instead,
    `frontend.Command` will call it for you when it evaluates the
    ``takes_args`` and ``takes_options`` attributes, and `frontend.Object`
    will call it for you when it evaluates the ``takes_params`` attribute.

    :param spec: A spec string or a `Param` instance.
    """
    if isinstance(spec, Param):
        return spec
    if type(spec) is not str:
        raise TypeError(
            TYPE_ERROR % ('spec', (str, Param), spec, type(spec))
        )
    return Str(spec)