def __init__(self, defaults=None, inifile=None, commandline=None, cascade=False):
self._cascade = cascade
self._subsections = OrderedDict()
self._defaults = OrderedDict()
self._load_defaults(defaults)
self._inifile = OrderedDict()
self._load_inifile(inifile)
self._inifilename = inifile
self._inifile_dirty = False
self._commandline = OrderedDict()
self._load_commandline(commandline)
self._parent = None
self._sectionkey = None
class LayeredConfig(object):
"""Provide unified access to nested configuration parameters. The
source Of these configuration parameters can be default
settings in code, a config file (using .ini-file style syntax)
and command line parameters. Comman line paramerrs override
Configuration file parameters, which in turn override default
settings in code (hence **Layered** Config).
Configuration parameters are accessed as regular object
attributes, not dict-style key/value pairs. Configuration
parameter names should therefore be regular python identifiers
(i.e. only consist of alphanumerical chars and '_').
Configuration parameters can be typed (strings, integers,
booleans, dates, lists...). Even though ini-style config files
and command line parameters are non-typed, by specifying default
settings in code, parameters from a config file or the commamd
line can be typed.
Configuration parameters can be changed in code. Such changes
are persisted to the configuration file by calling
:py:meth:`~ferenda.LayeredConfig.write`.
:param defaults: A dict with configuration keys and values. If
any values are dicts, these are turned into
nested config objects.
:type defaults: dict
:param inifile: The name of a ini-style configuration file. The
file should have a top-level section named
__root__, whose keys are turned into top-level
configuration parameters. Any other sections in
this file are turned into nested config
objects.
:param inifile: full path to a .ini-style config file.
:type inifile: str
:param commandline: The contents of sys.argv, or something
similar. Any long-style parameters are
turned into configuration values, and
parameters with hyphens are turned into
nested config objects
(i.e. ``--module-parameter=foo`` results
in self.module.parameter == "foo".
:type commandline: list
:param cascade: If an attempt to get a non-existing parameter
on a sub (nested) configuration object should
attempt to get the parameter on the parent
config object.
:param cascade: If a configuration key is not found,
search parent config object.
:type cascade: bool
Example::
>>> defaults = {'parameter': 'foo', 'other': 'default'}
>>> dir = tempfile.mkdtemp()
>>> inifile = dir + os.sep + "test.ini"
>>> with open(inifile, "w") as fp:
... res = fp.write("[__root__]\\nparameter = bar")
>>> argv = ['--parameter=baz']
>>> conf = LayeredConfig(defaults, inifile, argv)
>>> conf.parameter == 'baz'
True
>>> conf.other == 'default'
True
>>> conf.parameter = 'changed'
>>> conf.other = 'also changed'
>>> LayeredConfig.write(conf)
>>> with open(inifile) as fp:
... res = fp.read()
>>> res == '[__root__]\\nparameter = changed\\nother = also changed\\n\\n'
True
>>> os.unlink(inifile)
>>> os.rmdir(dir)
"""
def __init__(self, defaults=None, inifile=None, commandline=None, cascade=False):
self._cascade = cascade
self._subsections = OrderedDict()
self._defaults = OrderedDict()
self._load_defaults(defaults)
self._inifile = OrderedDict()
self._load_inifile(inifile)
self._inifilename = inifile
self._inifile_dirty = False
self._commandline = OrderedDict()
self._load_commandline(commandline)
self._parent = None
self._sectionkey = None
@staticmethod
def write(config):
"""Write changed properties to inifile (if provided at initialization)."""
root = config
while root._parent:
root = root._parent
if root._inifile_dirty:
with open(root._inifilename, "w") as fp:
root._configparser.write(fp)
def __iter__(self):
l = []
iterables = [self._commandline.keys(),
self._inifile.keys(),
self._defaults.keys()]
if self._cascade and self._parent:
iterables.append(self._parent)
for k in itertools.chain(*iterables):
if k not in l:
l.append(k)
yield k
def __getattribute__(self, name):
if name.startswith("_") or name == "write":
return object.__getattribute__(self, name)
if name in self._subsections:
return self._subsections[name]
if name in self._commandline:
return self._commandline[name]
if self._cascade:
current = self._parent
while current:
if name in current._commandline:
return current._commandline[name]
current = current._parent
if name in self._inifile:
return self._inifile[name]
if self._cascade:
current = self._parent
while current:
if name in current._inifile:
return current._inifile[name]
current = current._parent
if name in self._defaults:
if isinstance(self._defaults[name], type):
return None # it's typed and therefore exists, but has no value
else:
return self._defaults[name]
if self._cascade:
current = self._parent
while current:
if name in current._defaults:
if isinstance(current._defaults[name], type):
return None # it's typed and therefore exists, but has no value
else:
return current._defaults[name]
current = current._parent
raise AttributeError("Configuration key %s doesn't exist" % name)
def __setattr__(self, name, value):
# print("__setattribute__ %s to %s" % (name,value))
if name.startswith("_"):
object.__setattr__(self, name, value)
return
# First make sure that the higher-priority
# commandline-derived data doesn't shadow the new value.
if name in self._commandline:
del self._commandline[name]
# then update our internal representation
if name not in self._inifile:
self._inifile[name] = None
if value != self._inifile[name]:
self._inifile[name] = value
root = self
while root._parent:
root = root._parent
if root._inifilename:
root._inifile_dirty = True
# and finally update our associated cfgparser object so that we later
# can write() out the inifile. This lasts part is a bit complicated as
# we need to find the root LayeredConfig object where the cfgparser
# object resides.
root = self
sectionkeys = []
while root._parent:
# print("root._parent is not None")
sectionkeys.append(root._sectionkey)
root = root._parent
branch = root._configparser
if branch:
section = "".join(sectionkeys) # doesn't really work with more than 1 level
# print("Setting %s %s %s" % (section,name,str(value)))
if not section:
section = "__root__"
root._configparser.set(section, name, str(value))
else:
# If there is no _configparser object, then this
# LayeredConfig instance was created without one. There is
# no way to persist configuration values, so we're done
pass
def _load_defaults(self, defaults):
if not defaults:
return
for (k, v) in defaults.items():
if isinstance(v, dict):
self._subsections[k] = LayeredConfig(
defaults=v, cascade=self._cascade)
self._subsections[k]._sectionkey = k
self._subsections[k]._parent = self
else:
self._defaults[k] = v
def _load_inifile(self, inifilename):
if not inifilename:
self._configparser = None
return
if not os.path.exists(inifilename):
logging.warn("INI file %s does not exist" % inifilename)
self._configparser = None
return
self._configparser = configparser.ConfigParser(dict_type=OrderedDict)
self._configparser.read(inifilename)
if self._configparser.has_section('__root__'):
self._load_inifile_section('__root__')
for sectionkey in self._configparser.sections():
# Do we have a LayeredConfig object for sectionkey already?
if sectionkey not in self._subsections:
self._subsections[
sectionkey] = LayeredConfig(cascade=self._cascade)
self._subsections[sectionkey]._sectionkey = sectionkey
self._subsections[sectionkey]._parent = self
if self._subsections[sectionkey]._configparser is None:
self._subsections[
sectionkey]._configparser = self._configparser
self._subsections[sectionkey]._load_inifile_section(sectionkey)
# return cfgparser
def _type_value(self, key, value):
"""Find appropriate method/class constructor to convert a
string value to the correct type IF we know the correct
type."""
def boolconvert(value):
# not all bools should be converted, see test_typed_commandline
if value == "True":
return True
elif value == "False":
return False
else:
return value
def listconvert(value):
# this function is called with both string represenations
# of entire lists and simple (unquoted) strings. The
# ast.literal_eval handles the first case, and if the
# value can't be parsed as a python expression, it is
# returned verbatim (not wrapped in a list, for reasons)
try:
return ast.literal_eval(value)
except (SyntaxError, ValueError):
return value
def datetimeconvert(value):
try:
return datetime.datetime.strptime(value, "%Y-%m-%d %H:%M:%S.%f")
except ValueError:
return datetime.datetime.strptime(value, "%Y-%m-%d %H:%M:%S")
# find the appropriate defaults object. In the case of
# cascading, could be any parent that has a key key.
defaults = self._defaults # base case
if self._cascade:
cfg_obj = self
while cfg_obj is not None:
if key in cfg_obj._defaults:
defaults = cfg_obj._defaults
break # done!
if hasattr(cfg_obj, '_parent'):
cfg_obj = cfg_obj._parent
else:
cfg_obj = None
if key in defaults:
if type(defaults[key]) == type:
# print("Using class for %s" % key)
t = defaults[key]
else:
# print("Using instance for %s" % key)
t = type(defaults[key])
else:
t = str
if t == bool:
t = boolconvert
elif t == list:
t = listconvert
elif t == datetime.datetime:
t = datetimeconvert
# print("Converting %r to %r" % (value,t(value)))
return t(value)
def _load_inifile_section(self, sectionname):
for (key, value) in self._configparser.items(sectionname):
self._inifile[key] = self._type_value(key, value)
# For now: only support long arguments with = separating the parameter and the value, ie
# "./foo.py --longarg=value" works, "./foo.py --longarg value" or even
# "./foo.py --longarg = value" doesn't work.
def _load_commandline(self, commandline):
if not commandline:
return
for arg in commandline:
if arg.startswith("--"):
if "=" in arg:
(param, value) = arg.split("=", 1)
else:
(param, value) = (arg, True) # assume bool, not str
# '--param' => ['param']
# '--module-param' => ['module','param']
# Note: Options may not contains hyphens (ie they can't
# be called "parse-force") since this clashes with hyphen
# as the sectionkey separator.
parts = param[2:].split("-")
self._load_commandline_part(parts, value)
def _load_commandline_part(self, parts, value):
if len(parts) == 1:
key = parts[0]
if type(value) != bool: # bools are created implicitly for value-less options
value = self._type_value(key, value)
# create a new value, or append to an existing list?
if key in self._commandline:
if not isinstance(self._commandline[key], list):
self._commandline[key] = [self._commandline[key]]
self._commandline[key].append(value)
else:
self._commandline[key] = value
else:
(sectionkey) = parts[0]
if sectionkey not in self._subsections:
self._subsections[
sectionkey] = LayeredConfig(cascade=self._cascade)
self._subsections[sectionkey]._sectionkey = sectionkey
self._subsections[sectionkey]._parent = self
self._subsections[sectionkey]._load_commandline_part(parts[1:], value)
