tiramisu/tiramisu/config.py

# -*- coding: utf-8 -*-
# Copyright (C) 2012-2013 Team tiramisu (see AUTHORS for all contributors)
#
# This program 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 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# The original `Config` design model is unproudly borrowed from
# the rough pypy's guys: http://codespeak.net/svn/pypy/dist/pypy/config/
# the whole pypy projet is under MIT licence
# ____________________________________________________________
"options handler global entry point"
import weakref


from .error import PropertiesOptionError, ConfigError, ConflictError
from .option import OptionDescription, Option, SymLinkOption, \
    DynSymLinkOption
from .option.baseoption import valid_name
from .setting import groups, Settings, default_encoding, undefined
from .storage import get_storages, get_storage, set_storage, \
    _impl_getstate_setting, get_storages_validation
from .value import Values, Multi
from .i18n import _


class SubConfig(object):
    """Sub configuration management entry.
    Tree if OptionDescription's responsability. SubConfig are generated
    on-demand. A Config is also a SubConfig.
    Root Config is call context below
    """
    __slots__ = ('_impl_context', '_impl_descr', '_impl_path')

    def __init__(self, descr, context, subpath=None):
        """ Configuration option management master class

        :param descr: describes the configuration schema
        :type descr: an instance of ``option.OptionDescription``
        :param context: the current root config
        :type context: `Config`
        :type subpath: `str` with the path name
        """
        # main option description
        error = False
        try:
            if descr is not None and not descr.impl_is_optiondescription():  # pragma: optional cover
                error = True
        except AttributeError:
            error = True
        if error:
            raise TypeError(_('descr must be an optiondescription, not {0}'
                              ).format(type(descr)))
        self._impl_descr = descr
        # sub option descriptions
        if not isinstance(context, weakref.ReferenceType):  # pragma: optional cover
            raise ValueError('context must be a Weakref')
        self._impl_context = context
        self._impl_path = subpath

    def cfgimpl_reset_cache(self, only_expired=False, only=('values',
                                                            'settings')):
        "remove cache (in context)"
        self._cfgimpl_get_context().cfgimpl_reset_cache(only_expired, only)  # pragma: optional cover

    def cfgimpl_get_home_by_path(self, path, force_permissive=False):
        """:returns: tuple (config, name)"""
        path = path.split('.')
        for step in path[:-1]:
            self = self.getattr(step,
                                force_permissive=force_permissive)
        return self, path[-1]

    #def __hash__(self):
    #FIXME
    #    return hash(self.cfgimpl_get_description().impl_getkey(self))

    #def __eq__(self, other):
    #FIXME
    #    "Config's comparison"
    #    if not isinstance(other, Config):
    #        return False
    #    return self.cfgimpl_get_description().impl_getkey(self) == \
    #        other.cfgimpl_get_description().impl_getkey(other)

    #def __ne__(self, other):
    #FIXME
    #    "Config's comparison"
    #    if not isinstance(other, Config):
    #        return True
    #    return not self == other

    # ______________________________________________________________________
    def __iter__(self, force_permissive=False):
        """Pythonesque way of parsing group's ordered options.
        iteration only on Options (not OptionDescriptions)"""
        for child in self.cfgimpl_get_description()._impl_getchildren(
                context=self._cfgimpl_get_context()):
            if not child.impl_is_optiondescription():
                try:
                    name = child.impl_getname()
                    yield name, self.getattr(name,
                                             force_permissive=force_permissive)
                except GeneratorExit:  # pragma: optional cover
                    raise StopIteration
                except PropertiesOptionError:  # pragma: optional cover
                    pass  # option with properties

    def iter_all(self, force_permissive=False):
        """A way of parsing options **and** groups.
        iteration on Options and OptionDescriptions."""
        for child in self.cfgimpl_get_description().impl_getchildren():
            try:
                yield child.impl_getname(), self.getattr(child.impl_getname(),
                                                         force_permissive=force_permissive)
            except GeneratorExit:  # pragma: optional cover
                raise StopIteration
            except PropertiesOptionError:  # pragma: optional cover
                pass  # option with properties

    def iter_groups(self, group_type=None, force_permissive=False):
        """iteration on groups objects only.
        All groups are returned if `group_type` is `None`, otherwise the groups
        can be filtered by categories (families, or whatever).

        :param group_type: if defined, is an instance of `groups.GroupType`
                           or `groups.MasterGroupType` that lives in
                           `setting.groups`
        """
        if group_type is not None and not isinstance(group_type,
                                                     groups.GroupType):  # pragma: optional cover
            raise TypeError(_("unknown group_type: {0}").format(group_type))
        for child in self.cfgimpl_get_description()._impl_getchildren(
                context=self._cfgimpl_get_context()):
            if child.impl_is_optiondescription():
                try:
                    if group_type is None or (group_type is not None and
                                              child.impl_get_group_type()
                                              == group_type):
                        name = child.impl_getname()
                        yield name, self.getattr(name, force_permissive=force_permissive)
                except GeneratorExit:  # pragma: optional cover
                    raise StopIteration
                except PropertiesOptionError:  # pragma: optional cover
                    pass
    # ______________________________________________________________________

    def __str__(self):
        "Config's string representation"
        lines = []
        for name, grp in self.iter_groups():
            lines.append("[{0}]".format(name))
        for name, value in self:
            try:
                lines.append("{0} = {1}".format(name, value))
            except UnicodeEncodeError:  # pragma: optional cover
                lines.append("{0} = {1}".format(name,
                                                value.encode(default_encoding)))
        return '\n'.join(lines)

    __repr__ = __str__

    def _cfgimpl_get_context(self):
        """context could be None, we need to test it
        context is None only if all reference to `Config` object is deleted
        (for example we delete a `Config` and we manipulate a reference to
        old `SubConfig`, `Values`, `Multi` or `Settings`)
        """
        context = self._impl_context()
        if context is None:  # pragma: optional cover
            raise ConfigError(_('the context does not exist anymore'))
        return context

    def cfgimpl_get_description(self):
        if self._impl_descr is None:  # pragma: optional cover
            raise ConfigError(_('no option description found for this config'
                                ' (may be GroupConfig)'))
        else:
            return self._impl_descr

    def cfgimpl_get_settings(self):
        return self._cfgimpl_get_context()._impl_settings

    def cfgimpl_get_values(self):
        return self._cfgimpl_get_context()._impl_values

    # ____________________________________________________________
    # attribute methods
    def __setattr__(self, name, value):
        "attribute notation mechanism for the setting of the value of an option"
        self._setattr(name, value)

    def _setattr(self, name, value, force_permissive=False):
        if name.startswith('_impl_'):
            object.__setattr__(self, name, value)
            return
        if '.' in name:  # pragma: optional cover
            homeconfig, name = self.cfgimpl_get_home_by_path(name)
            return homeconfig._setattr(name, value, force_permissive)
        context = self._cfgimpl_get_context()
        child = self.cfgimpl_get_description().__getattr__(name,
                                                           context=context)
        if isinstance(child, OptionDescription):
            raise TypeError(_("can't assign to an OptionDescription"))  # pragma: optional cover
        elif isinstance(child, SymLinkOption) and \
                not isinstance(child, DynSymLinkOption):  # pragma: no dynoptiondescription cover
            path = context.cfgimpl_get_description().impl_get_path_by_opt(
                child._impl_getopt())
            context._setattr(path, value, force_permissive=force_permissive)
        else:
            subpath = self._get_subpath(name)
            self.cfgimpl_get_values().setitem(child, value, subpath,
                                              force_permissive=force_permissive)

    def __delattr__(self, name):
        context = self._cfgimpl_get_context()
        child = self.cfgimpl_get_description().__getattr__(name, context)
        self.cfgimpl_get_values().__delitem__(child)

    def __getattr__(self, name):
        return self.getattr(name)

    def _getattr(self, name, force_permissive=False, validate=True):  # pragma: optional cover
        """use getattr instead of _getattr
        """
        return self.getattr(name, force_permissive, validate)

    def _get_subpath(self, name):
        if self._impl_path is None:
            subpath = name
        else:
            subpath = self._impl_path + '.' + name
        return subpath

    def getattr(self, name, force_permissive=False, validate=True,
                _setting_properties=undefined, index=None):
        """
        attribute notation mechanism for accessing the value of an option
        :param name: attribute name
        :return: option's value if name is an option name, OptionDescription
                 otherwise
        """
        # attribute access by passing a path,
        # for instance getattr(self, "creole.general.family.adresse_ip_eth0")
        if '.' in name:
            homeconfig, name = self.cfgimpl_get_home_by_path(
                name, force_permissive=force_permissive)
            return homeconfig.getattr(name, force_permissive=force_permissive,
                                      validate=validate,
                                      _setting_properties=_setting_properties,
                                      index=index)
        context = self._cfgimpl_get_context()
        option = self.cfgimpl_get_description().__getattr__(name,
                                                            context=context)
        subpath = self._get_subpath(name)
        if isinstance(option, DynSymLinkOption):
            return self.cfgimpl_get_values()._get_cached_value(
                option, path=subpath,
                validate=validate,
                force_permissive=force_permissive,
                setting_properties=_setting_properties, index=index)
        elif isinstance(option, SymLinkOption):  # pragma: no dynoptiondescription cover
            path = context.cfgimpl_get_description().impl_get_path_by_opt(
                option._impl_getopt())
            return context.getattr(path, validate=validate,
                                   force_permissive=force_permissive,
                                   _setting_properties=_setting_properties,
                                   index=index)
        elif option.impl_is_optiondescription():
            self.cfgimpl_get_settings().validate_properties(
                option, True, False, path=subpath,
                force_permissive=force_permissive,
                setting_properties=_setting_properties)
            return SubConfig(option, self._impl_context, subpath)
        else:
            return self.cfgimpl_get_values()._get_cached_value(
                option, path=subpath,
                validate=validate,
                force_permissive=force_permissive,
                setting_properties=_setting_properties,
                index=index)

    def find(self, bytype=None, byname=None, byvalue=undefined, type_='option',
             check_properties=True, force_permissive=False):
        """
            finds a list of options recursively in the config

            :param bytype: Option class (BoolOption, StrOption, ...)
            :param byname: filter by Option.impl_getname()
            :param byvalue: filter by the option's value
            :returns: list of matching Option objects
        """
        return self._cfgimpl_get_context()._find(bytype, byname, byvalue,
                                                 first=False,
                                                 type_=type_,
                                                 _subpath=self.cfgimpl_get_path(False),
                                                 check_properties=check_properties,
                                                 force_permissive=force_permissive)

    def find_first(self, bytype=None, byname=None, byvalue=undefined,
                   type_='option', display_error=True, check_properties=True,
                   force_permissive=False):
        """
            finds an option recursively in the config

            :param bytype: Option class (BoolOption, StrOption, ...)
            :param byname: filter by Option.impl_getname()
            :param byvalue: filter by the option's value
            :returns: list of matching Option objects
        """
        return self._cfgimpl_get_context()._find(
            bytype, byname, byvalue, first=True, type_=type_,
            _subpath=self.cfgimpl_get_path(False), display_error=display_error,
            check_properties=check_properties,
            force_permissive=force_permissive)

    def _find(self, bytype, byname, byvalue, first, type_='option',
              _subpath=None, check_properties=True, display_error=True,
              force_permissive=False, only_path=undefined,
              only_option=undefined, setting_properties=undefined):
        """
        convenience method for finding an option that lives only in the subtree

        :param first: return only one option if True, a list otherwise
        :return: find list or an exception if nothing has been found
        """

        def _filter_by_value():
            if byvalue is undefined:
                return True
            try:
                value = self.getattr(path, force_permissive=force_permissive,
                                     _setting_properties=setting_properties)
                if isinstance(value, Multi):
                    return byvalue in value
                else:
                    return value == byvalue
            # a property is a restriction upon the access of the value
            except PropertiesOptionError:  # pragma: optional cover
                return False

        if type_ not in ('option', 'path', 'value'):  # pragma: optional cover
            raise ValueError(_('unknown type_ type {0}'
                               'for _find').format(type_))
        find_results = []
        # if value and/or check_properties are set, need all avalaible option
        # If first one has no good value or not good property check second one
        # and so on
        only_first = first is True and byvalue is None and \
            check_properties is None
        if only_path is not undefined:
            options = [(only_path, only_option)]
        else:
            options = self.cfgimpl_get_description().impl_get_options_paths(
                bytype, byname, _subpath, only_first,
                self._cfgimpl_get_context())
        for path, option in options:
            if not _filter_by_value():
                continue
            #remove option with propertyerror, ...
            if byvalue is undefined and check_properties:
                try:
                    value = self.getattr(path,
                                         force_permissive=force_permissive,
                                         _setting_properties=setting_properties)
                except PropertiesOptionError:  # pragma: optional cover
                    # a property restricts the access of the value
                    continue
            if type_ == 'value':
                retval = value
            elif type_ == 'path':
                retval = path
            elif type_ == 'option':
                retval = option
            if first:
                return retval
            else:
                find_results.append(retval)
        return self._find_return_results(find_results, display_error)

    def _find_return_results(self, find_results, display_error):
        if find_results == []:  # pragma: optional cover
            if display_error:
                raise AttributeError(_("no option found in config"
                                       " with these criteria"))
            else:
                # translation is slow
                raise AttributeError()
        else:
            return find_results

    def make_dict(self, flatten=False, _currpath=None, withoption=None,
                  withvalue=undefined, force_permissive=False,
                  setting_properties=undefined):
        """exports the whole config into a `dict`, for example:

        >>> print cfg.make_dict()
        {'od2.var4': None, 'od2.var5': None, 'od2.var6': None}



        :param flatten: returns a dict(name=value) instead of a dict(path=value)
                        ::

                            >>> print cfg.make_dict(flatten=True)
                            {'var5': None, 'var4': None, 'var6': None}

        :param withoption: returns the options that are present in the very same
                           `OptionDescription` than the `withoption` itself::

                                >>> print cfg.make_dict(withoption='var1')
                                {'od2.var4': None, 'od2.var5': None,
                                'od2.var6': None,
                                'od2.var1': u'value',
                                'od1.var1': None,
                                'od1.var3': None,
                                'od1.var2': None}

        :param withvalue: returns the options that have the value `withvalue`
                          ::

                            >>> print c.make_dict(withoption='var1',
                                                  withvalue=u'value')
                            {'od2.var4': None,
                            'od2.var5': None,
                            'od2.var6': None,
                            'od2.var1': u'value'}

        :returns: dict of Option's name (or path) and values
        """
        pathsvalues = []
        if _currpath is None:
            _currpath = []
        if withoption is None and withvalue is not undefined:  # pragma: optional cover
            raise ValueError(_("make_dict can't filtering with value without "
                               "option"))
        if setting_properties is undefined:
            setting_properties = self.cfgimpl_get_settings()._getproperties(
                read_write=False)
        if withoption is not None:
            context = self._cfgimpl_get_context()
            for path in context._find(bytype=None, byname=withoption,
                                      byvalue=withvalue, first=False,
                                      type_='path', _subpath=self.cfgimpl_get_path(False),
                                      force_permissive=force_permissive,
                                      setting_properties=setting_properties):
                path = '.'.join(path.split('.')[:-1])
                opt = context.unwrap_from_path(path, force_permissive=True)
                mypath = self.cfgimpl_get_path()
                if mypath is not None:
                    if mypath == path:
                        withoption = None
                        withvalue = undefined
                        break
                    else:
                        tmypath = mypath + '.'
                        if not path.startswith(tmypath):  # pragma: optional cover
                            raise AttributeError(_('unexpected path {0}, '
                                                   'should start with {1}'
                                                   '').format(path, mypath))
                        path = path[len(tmypath):]
                self._make_sub_dict(opt, path, pathsvalues, _currpath, flatten,
                                    force_permissive=force_permissive,
                                    setting_properties=setting_properties)
        #withoption can be set to None below !
        if withoption is None:
            for opt in self.cfgimpl_get_description().impl_getchildren():
                path = opt.impl_getname()
                self._make_sub_dict(opt, path, pathsvalues, _currpath, flatten,
                                    force_permissive=force_permissive,
                                    setting_properties=setting_properties)
        if _currpath == []:
            options = dict(pathsvalues)
            return options
        return pathsvalues

    def _make_sub_dict(self, opt, path, pathsvalues, _currpath, flatten,
                       setting_properties, force_permissive=False):
        try:
            if opt.impl_is_optiondescription():
                pathsvalues += self.getattr(path,
                                            force_permissive=force_permissive,
                                            _setting_properties=setting_properties).make_dict(
                                                flatten,
                                                _currpath + path.split('.'),
                                                force_permissive=force_permissive,
                                                setting_properties=setting_properties)
            else:
                value = self.getattr(opt.impl_getname(),
                                     force_permissive=force_permissive,
                                     _setting_properties=setting_properties)
                if flatten:
                    name = opt.impl_getname()
                else:
                    name = '.'.join(_currpath + [opt.impl_getname()])
                pathsvalues.append((name, value))
        except PropertiesOptionError:  # pragma: optional cover
            pass

    def cfgimpl_get_path(self, dyn=True):
        descr = self.cfgimpl_get_description()
        if not dyn and descr.impl_is_dynoptiondescription():
            context_descr = self._cfgimpl_get_context().cfgimpl_get_description()
            return context_descr.impl_get_path_by_opt(descr._impl_getopt())
        return self._impl_path


class _CommonConfig(SubConfig):
    "abstract base class for the Config, GroupConfig and the MetaConfig"
    __slots__ = ('_impl_values', '_impl_settings', '_impl_meta', '_impl_test')

    def _impl_build_all_caches(self):
        descr = self.cfgimpl_get_description()
        if not descr.impl_already_build_caches():
            descr.impl_build_cache()
            descr.impl_build_cache_option()

    def read_only(self):
        "read only is a global config's setting, see `settings.py`"
        self.cfgimpl_get_settings().read_only()

    def read_write(self):
        "read write is a global config's setting, see `settings.py`"
        self.cfgimpl_get_settings().read_write()

    def getowner(self, opt, index=None, force_permissive=False):
        """convenience method to retrieve an option's owner
        from the config itself
        """
        if not isinstance(opt, Option) and \
                not isinstance(opt, SymLinkOption) and \
                not isinstance(opt, DynSymLinkOption):  # pragma: optional cover
            raise TypeError(_('opt in getowner must be an option not {0}'
                              '').format(type(opt)))
        return self.cfgimpl_get_values().getowner(opt, index=index,
                                                  force_permissive=force_permissive)

    def unwrap_from_path(self, path, force_permissive=False):
        """convenience method to extract and Option() object from the Config()
        and it is **fast**: finds the option directly in the appropriate
        namespace

        :returns: Option()
        """
        context = self._cfgimpl_get_context()
        if '.' in path:
            homeconfig, path = self.cfgimpl_get_home_by_path(
                path, force_permissive=force_permissive)
            return homeconfig.cfgimpl_get_description().__getattr__(path, context=context)
        return self.cfgimpl_get_description().__getattr__(path, context=context)

    def cfgimpl_get_path(self, dyn=True):
        return None

    def cfgimpl_get_meta(self):
        if self._impl_meta is not None:
            return self._impl_meta()

    # information
    def impl_set_information(self, key, value):
        """updates the information's attribute

        :param key: information's key (ex: "help", "doc"
        :param value: information's value (ex: "the help string")
        """
        self._impl_values.set_information(key, value)

    def impl_get_information(self, key, default=undefined):
        """retrieves one information's item

        :param key: the item string (ex: "help")
        """
        return self._impl_values.get_information(key, default)

    # ----- state
    def __getstate__(self):
        if self._impl_meta is not None:
            raise ConfigError(_('cannot serialize Config with MetaConfig'))  # pragma: optional cover
        slots = set()
        for subclass in self.__class__.__mro__:
            if subclass is not object:
                slots.update(subclass.__slots__)
        slots -= frozenset(['_impl_context', '_impl_meta', '__weakref__'])
        state = {}
        for slot in slots:
            try:
                state[slot] = getattr(self, slot)
            except AttributeError:  # pragma: optional cover
                pass
        storage = self._impl_values._p_._storage
        if not storage.serializable:
            raise ConfigError(_('this storage is not serialisable, could be a '
                              'none persistent storage'))  # pragma: optional cover
        state['_storage'] = {'session_id': storage.session_id,
                             'persistent': storage.persistent}
        state['_impl_setting'] = _impl_getstate_setting()
        return state

    def __setstate__(self, state):
        for key, value in state.items():
            if key not in ['_storage', '_impl_setting']:
                setattr(self, key, value)
        set_storage('config', **state['_impl_setting'])
        self._impl_context = weakref.ref(self)
        self._impl_settings.context = weakref.ref(self)
        self._impl_values.context = weakref.ref(self)
        storage = get_storage('config', test=self._impl_test, **state['_storage'])
        self._impl_values._impl_setstate(storage)
        self._impl_settings._impl_setstate(storage)
        self._impl_meta = None

    def _gen_fake_values(self):
        fake_config = Config(self._impl_descr, persistent=False,
                             force_values=get_storages_validation(),
                             force_settings=self.cfgimpl_get_settings())
        fake_config.cfgimpl_get_values()._p_._values = self.cfgimpl_get_values()._p_._values
        return fake_config

    def duplicate(self):
        config = Config(self._impl_descr)
        config.cfgimpl_get_values()._p_._values = self.cfgimpl_get_values()._p_._values
        config.cfgimpl_get_settings()._p_._properties = self.cfgimpl_get_settings()._p_.get_modified_properties()
        config.cfgimpl_get_settings()._p_._permissives = self.cfgimpl_get_settings()._p_.get_modified_permissives()
        return config


# ____________________________________________________________
class Config(_CommonConfig):
    "main configuration management entry"
    __slots__ = ('__weakref__', '_impl_test', '_impl_name')

    def __init__(self, descr, session_id=None, persistent=False,
                 name=undefined, force_values=None, force_settings=None):
        """ Configuration option management master class

        :param descr: describes the configuration schema
        :type descr: an instance of ``option.OptionDescription``
        :param context: the current root config
        :type context: `Config`
        :param session_id: session ID is import with persistent Config to
        retrieve good session
        :type session_id: `str`
        :param persistent: if persistent, don't delete storage when leaving
        :type persistent: `boolean`
        """
        if force_settings is not None and force_values is not None:
            self._impl_settings = force_settings
            self._impl_values = Values(self, force_values)
        else:
            settings, values = get_storages(self, session_id, persistent)
            if name is undefined:
                name = 'config'
                if session_id is not None:
                    name += session_id
            if name is not None and not valid_name(name):  # pragma: optional cover
                raise ValueError(_("invalid name: {0} for config").format(name))
            self._impl_settings = Settings(self, settings)
            self._impl_values = Values(self, values)
        super(Config, self).__init__(descr, weakref.ref(self))
        self._impl_build_all_caches()
        self._impl_meta = None
        #undocumented option used only in test script
        self._impl_test = False
        self._impl_name = name

    def cfgimpl_reset_cache(self,
                            only_expired=False,
                            only=('values', 'settings')):
        if 'values' in only:
            self.cfgimpl_get_values().reset_cache(only_expired=only_expired)
        if 'settings' in only:
            self.cfgimpl_get_settings().reset_cache(only_expired=only_expired)

    def impl_getname(self):
        return self._impl_name


class GroupConfig(_CommonConfig):
    __slots__ = ('__weakref__', '_impl_children', '_impl_name')

    def __init__(self, children, session_id=None, persistent=False,
                 _descr=None, name=undefined):
        if not isinstance(children, list):
            raise ValueError(_("groupconfig's children must be a list"))
        names = []
        for child in children:
            if not isinstance(child, _CommonConfig):
                raise ValueError(_("groupconfig's children must be Config, MetaConfig or GroupConfig"))
            name_ = child._impl_name
            if name_ is None:
                raise ValueError(_('name must be set to config before creating groupconfig'))
            names.append(name_)
        if len(names) != len(set(names)):
            for idx in xrange(1, len(names) + 1):
                name = names.pop(0)
                if name in names:
                    raise ConflictError(_('config name must be uniq in '
                                          'groupconfig for {0}').format(name))
        self._impl_children = children
        settings, values = get_storages(self, session_id, persistent)
        self._impl_settings = Settings(self, settings)
        self._impl_values = Values(self, values)
        super(GroupConfig, self).__init__(_descr, weakref.ref(self))
        self._impl_meta = None
        #undocumented option used only in test script
        self._impl_test = False
        if name is undefined:
            name = session_id
        self._impl_name = name

    def cfgimpl_get_children(self):
        return self._impl_children

    #def cfgimpl_get_context(self):
    #    "a meta config is a config which has a setting, that is itself"
    #    return self

    def cfgimpl_reset_cache(self,
                            only_expired=False,
                            only=('values', 'settings')):
        if 'values' in only:
            self.cfgimpl_get_values().reset_cache(only_expired=only_expired)
        if 'settings' in only:
            self.cfgimpl_get_settings().reset_cache(only_expired=only_expired)
        for child in self._impl_children:
            child.cfgimpl_reset_cache(only_expired=only_expired, only=only)

    def set_value(self, path, value):
        """Setattr not in current GroupConfig, but in each children
        """
        for child in self._impl_children:
            try:
                if isinstance(child, MetaConfig):
                    child.set_value(path, value, only_config=True)
                elif isinstance(child, GroupConfig):
                    child.set_value(path, value)
                else:
                    setattr(child, path, value)
            except PropertiesOptionError:
                pass

    def find_firsts(self, byname=None, bypath=undefined, byoption=undefined,
                    byvalue=undefined, display_error=True, _sub=False,
                    check_properties=True):
        """Find first not in current GroupConfig, but in each children
        """
        ret = []

        #if MetaConfig, all children have same OptionDescription in context
        #so search only one time the option for all children
        if bypath is undefined and byname is not None and \
                isinstance(self, MetaConfig):
            bypath = self._find(bytype=None, byvalue=undefined, byname=byname,
                                first=True, type_='path',
                                check_properties=None,
                                display_error=display_error)
            byname = None
            byoption = self.cfgimpl_get_description(
            ).impl_get_opt_by_path(bypath)

        for child in self._impl_children:
            try:
                if isinstance(child, GroupConfig):
                    ret.extend(child.find_firsts(byname=byname, bypath=bypath,
                                                 byoption=byoption,
                                                 byvalue=byvalue,
                                                 check_properties=check_properties,
                                                 display_error=False,
                                                 _sub=True))
                else:
                    child._find(None, byname, byvalue, first=True,
                                type_='path', display_error=False,
                                check_properties=check_properties,
                                only_path=bypath, only_option=byoption)
                    ret.append(child)
            except AttributeError:
                pass
        if _sub:
            return ret
        else:
            return GroupConfig(self._find_return_results(ret, display_error))

    def __repr__(self):
        return object.__repr__(self)

    def __str__(self):
        ret = ''
        for child in self._impl_children:
            ret += '({0})\n'.format(child._impl_name)
        try:
            ret += super(GroupConfig, self).__str__()
        except ConfigError:
            pass
        return ret

    def getattr(self, name, force_permissive=False, validate=True,
                _setting_properties=undefined):
        for child in self._impl_children:
            if name == child._impl_name:
                return child
        return super(GroupConfig, self).getattr(name, force_permissive,
                                                validate,
                                                _setting_properties=_setting_properties)


class MetaConfig(GroupConfig):
    __slots__ = tuple()

    def __init__(self, children, session_id=None, persistent=False,
                 name=undefined):
        descr = None
        for child in children:
            if not isinstance(child, _CommonConfig):
                raise TypeError(_("metaconfig's children "
                                  "should be config, not {0}"
                                  ).format(type(child)))
            if child.cfgimpl_get_meta() is not None:
                raise ValueError(_("child has already a metaconfig's"))
            if descr is None:
                descr = child.cfgimpl_get_description()
            elif not descr is child.cfgimpl_get_description():
                raise ValueError(_('all config in metaconfig must '
                                   'have the same optiondescription'))
            child._impl_meta = weakref.ref(self)

        super(MetaConfig, self).__init__(children, session_id, persistent,
                                         descr, name)

    def set_value(self, path, value, force_default=False,
                  force_dont_change_value=False, force_default_if_same=False,
                  only_config=False):
        """only_config: could be set if you want modify value in all Config included in
                        this MetaConfig
        """
        if only_config:
            if force_default or force_default_if_same or force_dont_change_value:
                raise ValueError(_('force_default, force_default_if_same or '
                                   'force_dont_change_value cannot be set with'
                                   ' only_config'))
            return super(MetaConfig, self).set_value(path, value)
        if force_default or force_default_if_same or force_dont_change_value:
            if force_default and force_dont_change_value:
                raise ValueError(_('force_default and force_dont_change_value'
                                   ' cannot be set together'))
            opt = self.cfgimpl_get_description().impl_get_opt_by_path(path)
            for child in self._impl_children:
                if force_default_if_same or force_default:
                    if force_default_if_same:
                        if not child.cfgimpl_get_values()._contains(path):
                            child_value = undefined
                        else:
                            child_value = child.getattr(path)
                    if force_default or value == child_value:
                        child.cfgimpl_get_values().reset(opt, path=path,
                                                         validate=False)
                        continue
                if force_dont_change_value:
                    child_value = child.getattr(path)
                    if value != child_value:
                        setattr(child, path, child_value)

        setattr(self, path, value)