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# IVLE - Informatics Virtual Learning Environment
# Copyright (C) 2007-2009 The University of Melbourne
#
# 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 St, Fifth Floor, Boston, MA 02110-1301 USA
# Author: Matt Giuca, Will Grant
"""
Provides programmatic access to the IVLE configuration file.
"""
import os
import glob
import inspect
from configobj import ConfigObj
from validate import Validator
__all__ = ["ConfigError", "Config"]
class ConfigError(Exception):
"""
An error reading or writing the configuration file.
"""
pass
def search_confdir():
"""
Search for the config file, and return it as a filename.
1. Environment var IVLECONF (path to directory)
2. /etc/ivle/ivle.conf
Raises a ConfigError on error.
"""
if 'IVLECONF' in os.environ:
fname = os.path.join(os.environ['IVLECONF'])
if os.path.exists(fname):
return fname
if os.path.exists('/etc/ivle'):
return '/etc/ivle'
raise ConfigError("Could not find IVLE config directory")
def get_plugin(pluginstr):
plugin_path, classname = pluginstr.split('#')
# Load the plugin module from somewhere in the Python path
# (Note that plugin_path is a fully-qualified Python module name).
return (plugin_path,
getattr(__import__(plugin_path, fromlist=[classname]), classname))
_NO_VALUE = []
class Config(ConfigObj):
"""
The configuration object. Can be instantiated with no arguments (will
implicitly find the ivle.conf file and load it).
Automatically validates the file against the spec (found in
./ivle-spec.conf relative to this module).
"""
def __init__(self, blank=False, plugins=True, *args, **kwargs):
"""Initialises a new Config object. Searches for the config file,
loads it, and validates it.
@param blank: If blank=True, will create a blank config instead, and
not search for the config file.
@param plugins: If True, will find and index plugins.
@raise ConfigError: If the config file cannot be found.
"""
specfile = os.path.join(os.path.dirname(__file__), 'ivle-spec.conf')
if blank:
super(Config, self).__init__(configspec=specfile, *args, **kwargs)
else:
confdir = search_confdir()
conffile = os.path.join(confdir, 'ivle.conf')
super(Config, self).__init__(infile=conffile, configspec=specfile,
*args, **kwargs)
# XXX This doesn't raise errors if it doesn't validate
self.validate(Validator())
if not plugins:
return
self.plugins = {}
self.plugin_configs = {}
# Go through the plugin config files, looking for plugins.
for pconfn in glob.glob(os.path.join(confdir, 'plugins.d/*.conf')):
pconf = ConfigObj(pconfn)
for plugin_section in pconf:
# We have a plugin path. Resolve it into a class...
plugin_path, plugin = get_plugin(plugin_section)
self.plugins[plugin_path] = plugin
# ... and add it to the registry.
self.plugin_configs[plugin] = pconf[plugin_section]
# Create a registry mapping plugin classes to paths.
self.reverse_plugins = dict([(v, k) for (k, v) in
self.plugins.items()])
# Create an index of plugins by base class.
self.plugin_index = {}
for plugin in self.plugins.values():
# Getmro returns a tuple of all the super-classes of the plugin
for base in inspect.getmro(plugin):
if base not in self.plugin_index:
self.plugin_index[base] = []
self.plugin_index[base].append(plugin)
def set_by_path(self, path, value=_NO_VALUE, comment=None):
"""Writes a value to an option, given a '/'-separated path.
@param path: '/'-separated path to configuration option.
@param value: Optional - value to write to the option.
@param comment: Optional - comment string (lines separated by '\n's).
Note: If only a comment is being inserted, and the value does not
exist, fails silently.
"""
path = path.split('/')
# Iterate over each segment of the path, and find the section in conf
# file to insert the value into (use all but the last path segment)
conf_section = self
for seg in path[:-1]:
# Create the section if it isn't there
if seg not in conf_section:
conf_section[seg] = {}
conf_section = conf_section[seg]
# The final path segment names the key to insert into
keyname = path[-1]
if value is not _NO_VALUE:
conf_section[keyname] = value
if comment is not None:
try:
conf_section[keyname]
except KeyError:
pass # Fail silently
else:
conf_section.comments[keyname] = comment.split('\n')
def get_by_path(self, path):
"""Gets an option's value, given a '/'-separated path.
@param path: '/'-separated path to configuration option.
@raise KeyError: if no config option is at that path.
"""
# Iterate over each segment of the path, and find the value in conf file
value = self
for seg in path.split('/'):
value = value[seg] # May raise KeyError
return value
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