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# -*- coding: utf-8 -*-
# baseconfig.py
# Copyright (C) 2013 LEAP
#
# 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/>.
"""
Implements the abstract base class for configuration
"""
import copy
import logging
import functools
import os
from abc import ABCMeta, abstractmethod
from leap.common.check import leap_assert, leap_check
from leap.common.files import mkdir_p
from leap.common.config.pluggableconfig import PluggableConfig
from leap.common.config.prefixers import get_platform_prefixer
logger = logging.getLogger(__name__)
class NonExistingSchema(Exception):
"""
Raised if the schema needed to verify the config is None.
"""
class BaseConfig:
"""
Abstract base class for any JSON based configuration.
"""
__metaclass__ = ABCMeta
"""
Standalone is a class wide parameter.
:param standalone: if True it will return the prefix for a
standalone application. Otherwise, it will
return the system
default for configuration storage.
:type standalone: bool
"""
standalone = False
def __init__(self):
self._data = {}
self._config_checker = None
@abstractmethod
def _get_spec(self):
"""
Returns the spec object for the specific configuration.
"""
return None
def _safe_get_value(self, key):
"""
Tries to return a value only if the config has already been loaded.
:rtype: depends on the config structure, dict, str, array, int
:return: returns the value for the specified key in the config
"""
leap_assert(self._config_checker, "Load the config first")
return self._config_checker.config.get(key, None)
def get_path_prefix(self):
"""
Returns the platform dependant path prefixer
"""
return get_platform_prefixer().get_path_prefix(
standalone=self.standalone)
def loaded(self):
"""
Returns True if the configuration has been already
loaded. False otherwise
"""
return self._config_checker is not None
def save(self, path_list):
"""
Saves the current configuration to disk.
:param path_list: list of components that form the relative
path to configuration. The absolute path
will be calculated depending on the platform.
:type path_list: list
:return: True if saved to disk correctly, False otherwise
"""
config_path = os.path.join(self.get_path_prefix(), *(path_list[:-1]))
mkdir_p(config_path)
try:
self._config_checker.serialize(os.path.join(config_path,
path_list[-1]))
except Exception as e:
logger.warning("%s" % (e,))
raise
return True
def load(self, path="", data=None, mtime=None, relative=True):
"""
Loads the configuration from disk.
It may raise NonExistingSchema exception.
:param path: if relative=True, this is a relative path
to configuration. The absolute path
will be calculated depending on the platform
:type path: str
:param relative: if True, path is relative. If False, it's absolute.
:type relative: bool
:return: True if loaded from disk correctly, False otherwise
:rtype: bool
"""
if relative is True:
config_path = os.path.join(
self.get_path_prefix(), path)
else:
config_path = path
schema = self._get_spec()
leap_check(schema is not None,
"There is no schema to use.", NonExistingSchema)
self._config_checker = PluggableConfig(format="json")
self._config_checker.options = copy.deepcopy(schema)
try:
if data is None:
self._config_checker.load(fromfile=config_path, mtime=mtime)
else:
self._config_checker.load(data, mtime=mtime)
except Exception as e:
logger.error("Something went wrong while loading " +
"the config from %s\n%s" % (config_path, e))
self._config_checker = None
return False
return True
class LocalizedKey(object):
"""
Decorator used for keys that are localized in a configuration.
"""
def __init__(self, func, **kwargs):
self._func = func
def __call__(self, instance, lang=None):
"""
Tries to return the string for the specified language, otherwise
returns the default language string.
:param lang: language code
:type lang: str
:return: localized value from the possible values returned by
self._func
It returns None in case that the provider does not provides
a matching pair of default_language and string for
that language.
e.g.:
'default_language': 'es',
'description': {'en': 'test description'}
Note that the json schema can't check that.
"""
descriptions = self._func(instance)
config_lang = instance.get_default_language()
if lang is None:
lang = config_lang
for key in descriptions.keys():
if lang.startswith(key):
config_lang = key
break
description_lang = descriptions.get(config_lang)
if description_lang is None:
logger.error("There is a misconfiguration in the "
"provider's language strings.")
return description_lang
def __get__(self, instance, instancetype):
"""
Implement the descriptor protocol to make decorating instance
method possible.
"""
# Return a partial function with the first argument is the instance
# of the class decorated.
return functools.partial(self.__call__, instance)
if __name__ == "__main__":
try:
config = BaseConfig() # should throw TypeError for _get_spec
except Exception as e:
assert isinstance(e, TypeError), "Something went wrong"
print "Abstract BaseConfig class is working as expected"
|
