#!/usr/bin/env python
#
# config.py
# Allow configuration options to be set.
#
# Copyright (C) 2016 Gregory M. Green
#
# 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 2 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
from __future__ import print_function, division
import json
import os
class ConfigError(Exception):
pass
class Configuration(object):
"""
A class that stores the package configuration.
"""
def __init__(self, fname):
self._success = False
self.fname = fname
self.load()
def load(self):
if os.path.isfile(self.fname):
with open(self.fname, 'r') as f:
try:
self._options = json.load(f)
self._success = True
except ValueError as error:
print(('The config file appears to be corrupted:\n\n'
' {fname}\n\n'
'Either fix the config file manually, or overwrite '
'it with a blank configuration as follows:\n\n'
' from dustmaps.config import config\n'
' config.reset()\n\n'
'Note that this will delete your configuration! For '
'example, if you have specified a data directory, '
'then dustmaps will forget about its location.'
).format(fname=self.fname))
self._options = {}
else:
self._options = {}
self._success = True
def save(self, force=False):
"""
Saves the configuration to a JSON, in the standard config location.
Args:
force (Optional[:obj:`bool`]): Continue writing, even if the original
config file was not loaded properly. This is dangerous, because
it could cause the previous configuration options to be lost.
Defaults to :obj:`False`.
Raises:
:obj:`ConfigError`: if the configuration file was not successfully
loaded on initialization of the class, and
:obj:`force` is :obj:`False`.
"""
if (not self._success) and (not force):
raise ConfigError((
'The config file appears to be corrupted:\n\n'
' {fname}\n\n'
'Before attempting to save the configuration, please either '
'fix the config file manually, or overwrite it with a blank '
'configuration as follows:\n\n'
' from dustmaps.config import config\n'
' config.reset()\n\n'
).format(fname=self.fname))
with open(self.fname, 'w') as f:
json.dump(self._options, f, indent=2)
def __setitem__(self, key, value):
self._options[key] = value
self.save()
def __getitem__(self, key):
return self._options.get(key, None)
def get(self, key, default=None):
"""
Gets a configuration option, returning a default value if the specified
key isn't set.
"""
return self._options.get(key, default)
def remove(self, key):
"""
Deletes a key from the configuration.
"""
self._options.pop(key, None)
self.save()
def reset(self):
"""
Resets the configuration, and overwrites the existing configuration
file.
"""
self._options = {}
self.save(force=True)
self._success = True
# The package configuration filename
config_fname = os.path.expanduser('~/.dustmapsrc')
#: The package configuration. This is the object that the user should interact
#: with in order to change settings. For example, to set the directory where
#: large files (e.g., dust maps) will be stored:
#:
#: .. code-block:: python
#:
#: from dustmaps.config import config
#: config['data_dir'] = '/path/to/data/directory'
config = Configuration(config_fname)
