Source

logilab-common / configuration.py

Full commit
   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
# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common.  If not, see <http://www.gnu.org/licenses/>.
"""Classes to handle advanced configuration in simple to complex applications.

Allows to load the configuration from a file or from command line
options, to generate a sample configuration file or to display
program's usage. Fills the gap between optik/optparse and ConfigParser
by adding data types (which are also available as a standalone optik
extension in the `optik_ext` module).


Quick start: simplest usage
---------------------------

.. python ::

  >>> import sys
  >>> from logilab.common.configuration import Configuration
  >>> options = [('dothis', {'type':'yn', 'default': True, 'metavar': '<y or n>'}),
  ...            ('value', {'type': 'string', 'metavar': '<string>'}),
  ...            ('multiple', {'type': 'csv', 'default': ('yop',),
  ...                          'metavar': '<comma separated values>',
  ...                          'help': 'you can also document the option'}),
  ...            ('number', {'type': 'int', 'default':2, 'metavar':'<int>'}),
  ...           ]
  >>> config = Configuration(options=options, name='My config')
  >>> print config['dothis']
  True
  >>> print config['value']
  None
  >>> print config['multiple']
  ('yop',)
  >>> print config['number']
  2
  >>> print config.help()
  Usage:  [options]

  Options:
    -h, --help            show this help message and exit
    --dothis=<y or n>
    --value=<string>
    --multiple=<comma separated values>
                          you can also document the option [current: none]
    --number=<int>

  >>> f = open('myconfig.ini', 'w')
  >>> f.write('''[MY CONFIG]
  ... number = 3
  ... dothis = no
  ... multiple = 1,2,3
  ... ''')
  >>> f.close()
  >>> config.load_file_configuration('myconfig.ini')
  >>> print config['dothis']
  False
  >>> print config['value']
  None
  >>> print config['multiple']
  ['1', '2', '3']
  >>> print config['number']
  3
  >>> sys.argv = ['mon prog', '--value', 'bacon', '--multiple', '4,5,6',
  ...             'nonoptionargument']
  >>> print config.load_command_line_configuration()
  ['nonoptionargument']
  >>> print config['value']
  bacon
  >>> config.generate_config()
  # class for simple configurations which don't need the
  # manager / providers model and prefer delegation to inheritance
  #
  # configuration values are accessible through a dict like interface
  #
  [MY CONFIG]

  dothis=no

  value=bacon

  # you can also document the option
  multiple=4,5,6

  number=3
  >>>
"""
__docformat__ = "restructuredtext en"

__all__ = ('OptionsManagerMixIn', 'OptionsProviderMixIn',
           'ConfigurationMixIn', 'Configuration',
           'OptionsManager2ConfigurationAdapter')

import os
import sys
import re
from os.path import exists, expanduser
from copy import copy
from ConfigParser import ConfigParser, NoOptionError, NoSectionError, \
     DuplicateSectionError
from warnings import warn

from logilab.common.compat import callable, raw_input, str_encode as _encode

from logilab.common.textutils import normalize_text, unquote
from logilab.common import optik_ext as optparse

OptionError = optparse.OptionError

REQUIRED = []

class UnsupportedAction(Exception):
    """raised by set_option when it doesn't know what to do for an action"""


def _get_encoding(encoding, stream):
    encoding = encoding or getattr(stream, 'encoding', None)
    if not encoding:
        import locale
        encoding = locale.getpreferredencoding()
    return encoding


# validation functions ########################################################

def choice_validator(optdict, name, value):
    """validate and return a converted value for option of type 'choice'
    """
    if not value in optdict['choices']:
        msg = "option %s: invalid value: %r, should be in %s"
        raise optparse.OptionValueError(msg % (name, value, optdict['choices']))
    return value

def multiple_choice_validator(optdict, name, value):
    """validate and return a converted value for option of type 'choice'
    """
    choices = optdict['choices']
    values = optparse.check_csv(None, name, value)
    for value in values:
        if not value in choices:
            msg = "option %s: invalid value: %r, should be in %s"
            raise optparse.OptionValueError(msg % (name, value, choices))
    return values

def csv_validator(optdict, name, value):
    """validate and return a converted value for option of type 'csv'
    """
    return optparse.check_csv(None, name, value)

def yn_validator(optdict, name, value):
    """validate and return a converted value for option of type 'yn'
    """
    return optparse.check_yn(None, name, value)

def named_validator(optdict, name, value):
    """validate and return a converted value for option of type 'named'
    """
    return optparse.check_named(None, name, value)

def file_validator(optdict, name, value):
    """validate and return a filepath for option of type 'file'"""
    return optparse.check_file(None, name, value)

def color_validator(optdict, name, value):
    """validate and return a valid color for option of type 'color'"""
    return optparse.check_color(None, name, value)

def password_validator(optdict, name, value):
    """validate and return a string for option of type 'password'"""
    return optparse.check_password(None, name, value)

def date_validator(optdict, name, value):
    """validate and return a mx DateTime object for option of type 'date'"""
    return optparse.check_date(None, name, value)

def time_validator(optdict, name, value):
    """validate and return a time object for option of type 'time'"""
    return optparse.check_time(None, name, value)

def bytes_validator(optdict, name, value):
    """validate and return an integer for option of type 'bytes'"""
    return optparse.check_bytes(None, name, value)


VALIDATORS = {'string': unquote,
              'int': int,
              'float': float,
              'file': file_validator,
              'font': unquote,
              'color': color_validator,
              'regexp': re.compile,
              'csv': csv_validator,
              'yn': yn_validator,
              'bool': yn_validator,
              'named': named_validator,
              'password': password_validator,
              'date': date_validator,
              'time': time_validator,
              'bytes': bytes_validator,
              'choice': choice_validator,
              'multiple_choice': multiple_choice_validator,
              }

def _call_validator(opttype, optdict, option, value):
    if opttype not in VALIDATORS:
        raise Exception('Unsupported type "%s"' % opttype)
    try:
        return VALIDATORS[opttype](optdict, option, value)
    except TypeError:
        try:
            return VALIDATORS[opttype](value)
        except optparse.OptionValueError:
            raise
        except:
            raise optparse.OptionValueError('%s value (%r) should be of type %s' %
                                   (option, value, opttype))

# user input functions ########################################################

def input_password(optdict, question='password:'):
    from getpass import getpass
    while True:
        value = getpass(question)
        value2 = getpass('confirm: ')
        if value == value2:
            return value
        print 'password mismatch, try again'

def input_string(optdict, question):
    value = raw_input(question).strip()
    return value or None

def _make_input_function(opttype):
    def input_validator(optdict, question):
        while True:
            value = raw_input(question)
            if not value.strip():
                return None
            try:
                return _call_validator(opttype, optdict, None, value)
            except optparse.OptionValueError, ex:
                msg = str(ex).split(':', 1)[-1].strip()
                print 'bad value: %s' % msg
    return input_validator

INPUT_FUNCTIONS = {
    'string': input_string,
    'password': input_password,
    }

for opttype in VALIDATORS.keys():
    INPUT_FUNCTIONS.setdefault(opttype, _make_input_function(opttype))

def expand_default(self, option):
    """monkey patch OptionParser.expand_default since we have a particular
    way to handle defaults to avoid overriding values in the configuration
    file
    """
    if self.parser is None or not self.default_tag:
        return option.help
    optname = option._long_opts[0][2:]
    try:
        provider = self.parser.options_manager._all_options[optname]
    except KeyError:
        value = None
    else:
        optdict = provider.get_option_def(optname)
        optname = provider.option_name(optname, optdict)
        value = getattr(provider.config, optname, optdict)
        value = format_option_value(optdict, value)
    if value is optparse.NO_DEFAULT or not value:
        value = self.NO_DEFAULT_VALUE
    return option.help.replace(self.default_tag, str(value))


def convert(value, optdict, name=''):
    """return a validated value for an option according to its type

    optional argument name is only used for error message formatting
    """
    try:
        _type = optdict['type']
    except KeyError:
        # FIXME
        return value
    return _call_validator(_type, optdict, name, value)

def comment(string):
    """return string as a comment"""
    lines = [line.strip() for line in string.splitlines()]
    return '# ' + ('%s# ' % os.linesep).join(lines)

def format_time(value):
    if not value:
        return '0'
    if value != int(value):
        return '%.2fs' % value
    value = int(value)
    nbmin, nbsec = divmod(value, 60)
    if nbsec:
        return '%ss' % value
    nbhour, nbmin_ = divmod(nbmin, 60)
    if nbmin_:
        return '%smin' % nbmin
    nbday, nbhour_ = divmod(nbhour, 24)
    if nbhour_:
        return '%sh' % nbhour
    return '%sd' % nbday

def format_bytes(value):
    if not value:
        return '0'
    if value != int(value):
        return '%.2fB' % value
    value = int(value)
    prevunit = 'B'
    for unit in ('KB', 'MB', 'GB', 'TB'):
        next, remain = divmod(value, 1024)
        if remain:
            return '%s%s' % (value, prevunit)
        prevunit = unit
        value = next
    return '%s%s' % (value, unit)

def format_option_value(optdict, value):
    """return the user input's value from a 'compiled' value"""
    if isinstance(value, (list, tuple)):
        value = ','.join(value)
    elif isinstance(value, dict):
        value = ','.join(['%s:%s' % (k, v) for k, v in value.items()])
    elif hasattr(value, 'match'): # optdict.get('type') == 'regexp'
        # compiled regexp
        value = value.pattern
    elif optdict.get('type') == 'yn':
        value = value and 'yes' or 'no'
    elif isinstance(value, (str, unicode)) and value.isspace():
        value = "'%s'" % value
    elif optdict.get('type') == 'time' and isinstance(value, (float, int, long)):
        value = format_time(value)
    elif optdict.get('type') == 'bytes' and hasattr(value, '__int__'):
        value = format_bytes(value)
    return value

def ini_format_section(stream, section, options, encoding=None, doc=None):
    """format an options section using the INI format"""
    encoding = _get_encoding(encoding, stream)
    if doc:
        print >> stream, _encode(comment(doc), encoding)
    print >> stream, '[%s]' % section
    ini_format(stream, options, encoding)

def ini_format(stream, options, encoding):
    """format options using the INI format"""
    for optname, optdict, value in options:
        value = format_option_value(optdict, value)
        help = optdict.get('help')
        if help:
            help = normalize_text(help, line_len=79, indent='# ')
            print >> stream
            print >> stream, _encode(help, encoding)
        else:
            print >> stream
        if value is None:
            print >> stream, '#%s=' % optname
        else:
            value = _encode(value, encoding).strip()
            print >> stream, '%s=%s' % (optname, value)

format_section = ini_format_section

def rest_format_section(stream, section, options, encoding=None, doc=None):
    """format an options section using the INI format"""
    encoding = _get_encoding(encoding, stream)
    if section:
        print >> stream, '%s\n%s' % (section, "'"*len(section))
    if doc:
        print >> stream, _encode(normalize_text(doc, line_len=79, indent=''),
                                 encoding)
        print >> stream
    for optname, optdict, value in options:
        help = optdict.get('help')
        print >> stream, ':%s:' % optname
        if help:
            help = normalize_text(help, line_len=79, indent='  ')
            print >> stream, _encode(help, encoding)
        if value:
            value = _encode(format_option_value(optdict, value), encoding)
            print >> stream, ''
            print >> stream, '  Default: ``%s``' % value.replace("`` ", "```` ``")


class OptionsManagerMixIn(object):
    """MixIn to handle a configuration from both a configuration file and
    command line options
    """

    def __init__(self, usage, config_file=None, version=None, quiet=0):
        self.config_file = config_file
        self.reset_parsers(usage, version=version)
        # list of registered options providers
        self.options_providers = []
        # dictionary associating option name to checker
        self._all_options = {}
        self._short_options = {}
        self._nocallback_options = {}
        self._mygroups = dict()
        # verbosity
        self.quiet = quiet
        self._maxlevel = 0

    def reset_parsers(self, usage='', version=None):
        # configuration file parser
        self.cfgfile_parser = ConfigParser()
        # command line parser
        self.cmdline_parser = optparse.OptionParser(usage=usage, version=version)
        self.cmdline_parser.options_manager = self
        self._optik_option_attrs = set(self.cmdline_parser.option_class.ATTRS)

    def register_options_provider(self, provider, own_group=True):
        """register an options provider"""
        assert provider.priority <= 0, "provider's priority can't be >= 0"
        for i in range(len(self.options_providers)):
            if provider.priority > self.options_providers[i].priority:
                self.options_providers.insert(i, provider)
                break
        else:
            self.options_providers.append(provider)
        non_group_spec_options = [option for option in provider.options
                                  if 'group' not in option[1]]
        groups = getattr(provider, 'option_groups', ())
        if own_group and non_group_spec_options:
            self.add_option_group(provider.name.upper(), provider.__doc__,
                                  non_group_spec_options, provider)
        else:
            for opt, optdict in non_group_spec_options:
                self.add_optik_option(provider, self.cmdline_parser, opt, optdict)
        for gname, gdoc in groups:
            gname = gname.upper()
            goptions = [option for option in provider.options
                        if option[1].get('group', '').upper() == gname]
            self.add_option_group(gname, gdoc, goptions, provider)

    def add_option_group(self, group_name, doc, options, provider):
        """add an option group including the listed options
        """
        assert options
        # add option group to the command line parser
        if group_name in self._mygroups:
            group = self._mygroups[group_name]
        else:
            group = optparse.OptionGroup(self.cmdline_parser,
                                         title=group_name.capitalize())
            self.cmdline_parser.add_option_group(group)
            group.level = provider.level
            self._mygroups[group_name] = group
            # add section to the config file
            if group_name != "DEFAULT":
                self.cfgfile_parser.add_section(group_name)
        # add provider's specific options
        for opt, optdict in options:
            self.add_optik_option(provider, group, opt, optdict)

    def add_optik_option(self, provider, optikcontainer, opt, optdict):
        if 'inputlevel' in optdict:
            warn('[0.50] "inputlevel" in option dictionary for %s is deprecated,'
                 ' use "level"' % opt, DeprecationWarning)
            optdict['level'] = optdict.pop('inputlevel')
        args, optdict = self.optik_option(provider, opt, optdict)
        option = optikcontainer.add_option(*args, **optdict)
        self._all_options[opt] = provider
        self._maxlevel = max(self._maxlevel, option.level or 0)

    def optik_option(self, provider, opt, optdict):
        """get our personal option definition and return a suitable form for
        use with optik/optparse
        """
        optdict = copy(optdict)
        others = {}
        if 'action' in optdict:
            self._nocallback_options[provider] = opt
        else:
            optdict['action'] = 'callback'
            optdict['callback'] = self.cb_set_provider_option
        # default is handled here and *must not* be given to optik if you
        # want the whole machinery to work
        if 'default' in optdict:
            if (optparse.OPTPARSE_FORMAT_DEFAULT and 'help' in optdict and
                optdict.get('default') is not None and
                not optdict['action'] in ('store_true', 'store_false')):
                optdict['help'] += ' [current: %default]'
            del optdict['default']
        args = ['--' + str(opt)]
        if 'short' in optdict:
            self._short_options[optdict['short']] = opt
            args.append('-' + optdict['short'])
            del optdict['short']
        # cleanup option definition dict before giving it to optik
        for key in optdict.keys():
            if not key in self._optik_option_attrs:
                optdict.pop(key)
        return args, optdict

    def cb_set_provider_option(self, option, opt, value, parser):
        """optik callback for option setting"""
        if opt.startswith('--'):
            # remove -- on long option
            opt = opt[2:]
        else:
            # short option, get its long equivalent
            opt = self._short_options[opt[1:]]
        # trick since we can't set action='store_true' on options
        if value is None:
            value = 1
        self.global_set_option(opt, value)

    def global_set_option(self, opt, value):
        """set option on the correct option provider"""
        self._all_options[opt].set_option(opt, value)

    def generate_config(self, stream=None, skipsections=(), encoding=None):
        """write a configuration file according to the current configuration
        into the given stream or stdout
        """
        options_by_section = {}
        sections = []
        for provider in self.options_providers:
            for section, options in provider.options_by_section():
                if section is None:
                    section = provider.name
                if section in skipsections:
                    continue
                options = [(n, d, v) for (n, d, v) in options
                           if d.get('type') is not None]
                if not options:
                    continue
                if not section in sections:
                    sections.append(section)
                alloptions = options_by_section.setdefault(section, [])
                alloptions += options
        stream = stream or sys.stdout
        encoding = _get_encoding(encoding, stream)
        printed = False
        for section in sections:
            if printed:
                print >> stream, '\n'
            format_section(stream, section.upper(), options_by_section[section],
                           encoding)
            printed = True

    def generate_manpage(self, pkginfo, section=1, stream=None):
        """write a man page for the current configuration into the given
        stream or stdout
        """
        self._monkeypatch_expand_default()
        try:
            optparse.generate_manpage(self.cmdline_parser, pkginfo,
                                      section, stream=stream or sys.stdout,
                                      level=self._maxlevel)
        finally:
            self._unmonkeypatch_expand_default()

    # initialization methods ##################################################

    def load_provider_defaults(self):
        """initialize configuration using default values"""
        for provider in self.options_providers:
            provider.load_defaults()

    def load_file_configuration(self, config_file=None):
        """load the configuration from file"""
        self.read_config_file(config_file)
        self.load_config_file()

    def read_config_file(self, config_file=None):
        """read the configuration file but do not load it (i.e. dispatching
        values to each options provider)
        """
        helplevel = 1
        while helplevel <= self._maxlevel:
            opt = '-'.join(['long'] * helplevel) + '-help'
            if opt in self._all_options:
                break # already processed
            def helpfunc(option, opt, val, p, level=helplevel):
                print self.help(level)
                sys.exit(0)
            helpmsg = '%s verbose help.' % ' '.join(['more'] * helplevel)
            optdict = {'action' : 'callback', 'callback' : helpfunc,
                       'help' : helpmsg}
            provider = self.options_providers[0]
            self.add_optik_option(provider, self.cmdline_parser, opt, optdict)
            provider.options += ( (opt, optdict), )
            helplevel += 1
        if config_file is None:
            config_file = self.config_file
        if config_file is not None:
            config_file = expanduser(config_file)
        if config_file and exists(config_file):
            parser = self.cfgfile_parser
            parser.read([config_file])
            # normalize sections'title
            for sect, values in parser._sections.items():
                if not sect.isupper() and values:
                    parser._sections[sect.upper()] = values
        elif not self.quiet:
            msg = 'No config file found, using default configuration'
            print >> sys.stderr, msg
            return

    def input_config(self, onlysection=None, inputlevel=0, stream=None):
        """interactively get configuration values by asking to the user and generate
        a configuration file
        """
        if onlysection is not None:
            onlysection = onlysection.upper()
        for provider in self.options_providers:
            for section, option, optdict in provider.all_options():
                if onlysection is not None and section != onlysection:
                    continue
                if not 'type' in optdict:
                    # ignore action without type (callback, store_true...)
                    continue
                provider.input_option(option, optdict, inputlevel)
        # now we can generate the configuration file
        if stream is not None:
            self.generate_config(stream)

    def load_config_file(self):
        """dispatch values previously read from a configuration file to each
        options provider)
        """
        parser = self.cfgfile_parser
        for provider in self.options_providers:
            for section, option, optdict in provider.all_options():
                try:
                    value = parser.get(section, option)
                    provider.set_option(option, value, optdict=optdict)
                except (NoSectionError, NoOptionError), ex:
                    continue

    def load_configuration(self, **kwargs):
        """override configuration according to given parameters
        """
        for opt, opt_value in kwargs.items():
            opt = opt.replace('_', '-')
            provider = self._all_options[opt]
            provider.set_option(opt, opt_value)

    def load_command_line_configuration(self, args=None):
        """override configuration according to command line parameters

        return additional arguments
        """
        self._monkeypatch_expand_default()
        try:
            if args is None:
                args = sys.argv[1:]
            else:
                args = list(args)
            (options, args) = self.cmdline_parser.parse_args(args=args)
            for provider in self._nocallback_options.keys():
                config = provider.config
                for attr in config.__dict__.keys():
                    value = getattr(options, attr, None)
                    if value is None:
                        continue
                    setattr(config, attr, value)
            return args
        finally:
            self._unmonkeypatch_expand_default()


    # help methods ############################################################

    def add_help_section(self, title, description, level=0):
        """add a dummy option section for help purpose """
        group = optparse.OptionGroup(self.cmdline_parser,
                                     title=title.capitalize(),
                                     description=description)
        group.level = level
        self._maxlevel = max(self._maxlevel, level)
        self.cmdline_parser.add_option_group(group)

    def _monkeypatch_expand_default(self):
        # monkey patch optparse to deal with our default values
        try:
            self.__expand_default_backup = optparse.HelpFormatter.expand_default
            optparse.HelpFormatter.expand_default = expand_default
        except AttributeError:
            # python < 2.4: nothing to be done
            pass
    def _unmonkeypatch_expand_default(self):
        # remove monkey patch
        if hasattr(optparse.HelpFormatter, 'expand_default'):
            # unpatch optparse to avoid side effects
            optparse.HelpFormatter.expand_default = self.__expand_default_backup

    def help(self, level=0):
        """return the usage string for available options """
        self.cmdline_parser.formatter.output_level = level
        self._monkeypatch_expand_default()
        try:
            return self.cmdline_parser.format_help()
        finally:
            self._unmonkeypatch_expand_default()


class Method(object):
    """used to ease late binding of default method (so you can define options
    on the class using default methods on the configuration instance)
    """
    def __init__(self, methname):
        self.method = methname
        self._inst = None

    def bind(self, instance):
        """bind the method to its instance"""
        if self._inst is None:
            self._inst = instance

    def __call__(self, *args, **kwargs):
        assert self._inst, 'unbound method'
        return getattr(self._inst, self.method)(*args, **kwargs)


class OptionsProviderMixIn(object):
    """Mixin to provide options to an OptionsManager"""

    # those attributes should be overridden
    priority = -1
    name = 'default'
    options = ()
    level = 0

    def __init__(self):
        self.config = optparse.Values()
        for option in self.options:
            try:
                option, optdict = option
            except ValueError:
                raise Exception('Bad option: %r' % option)
            if isinstance(optdict.get('default'), Method):
                optdict['default'].bind(self)
            elif isinstance(optdict.get('callback'), Method):
                optdict['callback'].bind(self)
        self.load_defaults()

    def load_defaults(self):
        """initialize the provider using default values"""
        for opt, optdict in self.options:
            action = optdict.get('action')
            if action != 'callback':
                # callback action have no default
                default = self.option_default(opt, optdict)
                if default is REQUIRED:
                    continue
                self.set_option(opt, default, action, optdict)

    def option_default(self, opt, optdict=None):
        """return the default value for an option"""
        if optdict is None:
            optdict = self.get_option_def(opt)
        default = optdict.get('default')
        if callable(default):
            default = default()
        return default

    def option_name(self, opt, optdict=None):
        """get the config attribute corresponding to opt
        """
        if optdict is None:
            optdict = self.get_option_def(opt)
        return optdict.get('dest', opt.replace('-', '_'))

    def option_value(self, opt):
        """get the current value for the given option"""
        return getattr(self.config, self.option_name(opt), None)

    def set_option(self, opt, value, action=None, optdict=None):
        """method called to set an option (registered in the options list)
        """
        # print "************ setting option", opt," to value", value
        if optdict is None:
            optdict = self.get_option_def(opt)
        if value is not None:
            value = convert(value, optdict, opt)
        if action is None:
            action = optdict.get('action', 'store')
        if optdict.get('type') == 'named': # XXX need specific handling
            optname = self.option_name(opt, optdict)
            currentvalue = getattr(self.config, optname, None)
            if currentvalue:
                currentvalue.update(value)
                value = currentvalue
        if action == 'store':
            setattr(self.config, self.option_name(opt, optdict), value)
        elif action in ('store_true', 'count'):
            setattr(self.config, self.option_name(opt, optdict), 0)
        elif action == 'store_false':
            setattr(self.config, self.option_name(opt, optdict), 1)
        elif action == 'append':
            opt = self.option_name(opt, optdict)
            _list = getattr(self.config, opt, None)
            if _list is None:
                if isinstance(value, (list, tuple)):
                    _list = value
                elif value is not None:
                    _list = []
                    _list.append(value)
                setattr(self.config, opt, _list)
            elif isinstance(_list, tuple):
                setattr(self.config, opt, _list + (value,))
            else:
                _list.append(value)
        elif action == 'callback':
            optdict['callback'](None, opt, value, None)
        else:
            raise UnsupportedAction(action)

    def input_option(self, option, optdict, inputlevel=99):
        default = self.option_default(option, optdict)
        if default is REQUIRED:
            defaultstr = '(required): '
        elif optdict.get('level', 0) > inputlevel:
            return
        elif optdict['type'] == 'password' or default is None:
            defaultstr = ': '
        else:
            defaultstr = '(default: %s): ' % format_option_value(optdict, default)
        print ':%s:' % option
        print optdict.get('help') or option
        inputfunc = INPUT_FUNCTIONS[optdict['type']]
        value = inputfunc(optdict, defaultstr)
        while default is REQUIRED and not value:
            print 'please specify a value'
            value = inputfunc(optdict, '%s: ' % option)
        if value is None and default is not None:
            value = default
        self.set_option(option, value, optdict=optdict)

    def get_option_def(self, opt):
        """return the dictionary defining an option given it's name"""
        assert self.options
        for option in self.options:
            if option[0] == opt:
                return option[1]
        raise OptionError('no such option %s in section %r'
                          % (opt, self.name), opt)


    def all_options(self):
        """return an iterator on available options for this provider
        option are actually described by a 3-uple:
        (section, option name, option dictionary)
        """
        for section, options in self.options_by_section():
            if section is None:
                if self.name is None:
                    continue
                section = self.name.upper()
            for option, optiondict, value in options:
                yield section, option, optiondict

    def options_by_section(self):
        """return an iterator on options grouped by section

        (section, [list of (optname, optdict, optvalue)])
        """
        sections = {}
        for optname, optdict in self.options:
            sections.setdefault(optdict.get('group'), []).append(
                (optname, optdict, self.option_value(optname)))
        if None in sections:
            yield None, sections.pop(None)
        for section, options in sections.items():
            yield section.upper(), options

    def options_and_values(self, options=None):
        if options is None:
            options = self.options
        for optname, optdict in options:
            yield (optname, optdict, self.option_value(optname))


class ConfigurationMixIn(OptionsManagerMixIn, OptionsProviderMixIn):
    """basic mixin for simple configurations which don't need the
    manager / providers model
    """
    def __init__(self, *args, **kwargs):
        if not args:
            kwargs.setdefault('usage', '')
        kwargs.setdefault('quiet', 1)
        OptionsManagerMixIn.__init__(self, *args, **kwargs)
        OptionsProviderMixIn.__init__(self)
        if not getattr(self, 'option_groups', None):
            self.option_groups = []
            for option, optdict in self.options:
                try:
                    gdef = (optdict['group'].upper(), '')
                except KeyError:
                    continue
                if not gdef in self.option_groups:
                    self.option_groups.append(gdef)
        self.register_options_provider(self, own_group=0)

    def register_options(self, options):
        """add some options to the configuration"""
        options_by_group = {}
        for optname, optdict in options:
            options_by_group.setdefault(optdict.get('group', self.name.upper()), []).append((optname, optdict))
        for group, options in options_by_group.items():
            self.add_option_group(group, None, options, self)
        self.options += tuple(options)

    def load_defaults(self):
        OptionsProviderMixIn.load_defaults(self)

    def __iter__(self):
        return iter(self.config.__dict__.iteritems())

    def __getitem__(self, key):
        try:
            return getattr(self.config, self.option_name(key))
        except (optparse.OptionValueError, AttributeError):
            raise KeyError(key)

    def __setitem__(self, key, value):
        self.set_option(key, value)

    def get(self, key, default=None):
        try:
            return getattr(self.config, self.option_name(key))
        except (OptionError, AttributeError):
            return default


class Configuration(ConfigurationMixIn):
    """class for simple configurations which don't need the
    manager / providers model and prefer delegation to inheritance

    configuration values are accessible through a dict like interface
    """

    def __init__(self, config_file=None, options=None, name=None,
                 usage=None, doc=None, version=None):
        if options is not None:
            self.options = options
        if name is not None:
            self.name = name
        if doc is not None:
            self.__doc__ = doc
        super(Configuration, self).__init__(config_file=config_file, usage=usage, version=version)


class OptionsManager2ConfigurationAdapter(object):
    """Adapt an option manager to behave like a
    `logilab.common.configuration.Configuration` instance
    """
    def __init__(self, provider):
        self.config = provider

    def __getattr__(self, key):
        return getattr(self.config, key)

    def __getitem__(self, key):
        provider = self.config._all_options[key]
        try:
            return getattr(provider.config, provider.option_name(key))
        except AttributeError:
            raise KeyError(key)

    def __setitem__(self, key, value):
        self.config.global_set_option(self.config.option_name(key), value)

    def get(self, key, default=None):
        provider = self.config._all_options[key]
        try:
            return getattr(provider.config, provider.option_name(key))
        except AttributeError:
            return default


def read_old_config(newconfig, changes, configfile):
    """initialize newconfig from a deprecated configuration file

    possible changes:
    * ('renamed', oldname, newname)
    * ('moved', option, oldgroup, newgroup)
    * ('typechanged', option, oldtype, newvalue)
    """
    # build an index of changes
    changesindex = {}
    for action in changes:
        if action[0] == 'moved':
            option, oldgroup, newgroup = action[1:]
            changesindex.setdefault(option, []).append((action[0], oldgroup, newgroup))
            continue
        if action[0] == 'renamed':
            oldname, newname = action[1:]
            changesindex.setdefault(newname, []).append((action[0], oldname))
            continue
        if action[0] == 'typechanged':
            option, oldtype, newvalue = action[1:]
            changesindex.setdefault(option, []).append((action[0], oldtype, newvalue))
            continue
        if action[1] in ('added', 'removed'):
            continue # nothing to do here
        raise Exception('unknown change %s' % action[0])
    # build a config object able to read the old config
    options = []
    for optname, optdef in newconfig.options:
        for action in changesindex.pop(optname, ()):
            if action[0] == 'moved':
                oldgroup, newgroup = action[1:]
                optdef = optdef.copy()
                optdef['group'] = oldgroup
            elif action[0] == 'renamed':
                optname = action[1]
            elif action[0] == 'typechanged':
                oldtype = action[1]
                optdef = optdef.copy()
                optdef['type'] = oldtype
        options.append((optname, optdef))
    if changesindex:
        raise Exception('unapplied changes: %s' % changesindex)
    oldconfig = Configuration(options=options, name=newconfig.name)
    # read the old config
    oldconfig.load_file_configuration(configfile)
    # apply values reverting changes
    changes.reverse()
    done = set()
    for action in changes:
        if action[0] == 'renamed':
            oldname, newname = action[1:]
            newconfig[newname] = oldconfig[oldname]
            done.add(newname)
        elif action[0] == 'typechanged':
            optname, oldtype, newvalue = action[1:]
            newconfig[optname] = newvalue
            done.add(optname)
    for optname, optdef in newconfig.options:
        if optdef.get('type') and not optname in done:
            newconfig.set_option(optname, oldconfig[optname], optdict=optdef)


def merge_options(options):
    """preprocess options to remove duplicate"""
    alloptions = {}
    options = list(options)
    for i in range(len(options)-1, -1, -1):
        optname, optdict = options[i]
        if optname in alloptions:
            options.pop(i)
            alloptions[optname].update(optdict)
        else:
            alloptions[optname] = optdict
    return tuple(options)