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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 logging
import functools
import os
import errno
import copy
from abc import ABCMeta, abstractmethod
from leap.config.prefixers import get_platform_prefixer
from leap.config.pluggableconfig import PluggableConfig
logger = logging.getLogger(__name__)
class BaseConfig:
"""
Abstract base class for any JSON based configuration
"""
__metaclass__ = ABCMeta
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
"""
assert self._config_checker, "Load the config first"
return self._config_checker.config[key]
def get_path_prefix(self, standalone=False):
"""
Returns the platform dependant path prefixer
@param standalone: if True it will return the prefix for a
standalone application. Otherwise, it will return the system
default for configuration storage.
@param type: bool
"""
return get_platform_prefixer().get_path_prefix(standalone=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: relative path to configuration. The absolute path
will be calculated depending on the platform.
@type path: list
@return: True if saved to disk correctly, False otherwise
"""
config_path = os.path.join(self.get_path_prefix(), *(path_list[:-1]))
try:
os.makedirs(config_path)
except OSError as e:
if e.errno == errno.EEXIST and os.path.isdir(config_path):
pass
else:
raise
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):
"""
Loads the configuration from disk
@type path: str
@param path: relative path to configuration. The absolute path
will be calculated depending on the platform
@return: True if loaded to disk correctly, False otherwise
"""
# TODO: retrieve standalone option from app-level config
config_path = os.path.join(self.get_path_prefix(),
path)
self._config_checker = PluggableConfig(format="json")
self._config_checker.options = copy.deepcopy(self._get_spec())
try:
if data is None:
self._config_checker.load(fromfile=config_path)
else:
self._config_checker.load(data)
except Exception as e:
logger.warning("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="en"):
"""
Tries to return the string for the specified language, otherwise
informs the problem and returns an empty string
@param lang: language code
@param type: str
@return: localized value from the possible values returned by
self._func
"""
descriptions = self._func(instance)
description_lang = ""
if lang in descriptions.keys():
description_lang = descriptions[lang]
else:
logger.warning("Unknown language: %s" % (lang,))
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"
|
