##// END OF EJS Templates
skip permission -> 403 test on Windows...
skip permission -> 403 test on Windows The test actually passes on my VM (Win 7), but not on Jenkins (Server 2012). I haven't figured out how to identify the subset of Windows systems where it won't work, but since the problem appears to be in the test, not the tested code, skipping on Windows seems the right way to go.

File last commit:

r19466:7ffd6d06
r20575:7211fc10
Show More
configurable.py
369 lines | 13.4 KiB | text/x-python | PythonLexer
# encoding: utf-8
"""A base class for objects that are configurable."""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
from __future__ import print_function
import logging
from copy import deepcopy
from .loader import Config, LazyConfigValue
from IPython.utils.traitlets import HasTraits, Instance
from IPython.utils.text import indent, wrap_paragraphs
from IPython.utils.py3compat import iteritems
#-----------------------------------------------------------------------------
# Helper classes for Configurables
#-----------------------------------------------------------------------------
class ConfigurableError(Exception):
pass
class MultipleInstanceError(ConfigurableError):
pass
#-----------------------------------------------------------------------------
# Configurable implementation
#-----------------------------------------------------------------------------
class Configurable(HasTraits):
config = Instance(Config, (), {})
parent = Instance('IPython.config.configurable.Configurable')
def __init__(self, **kwargs):
"""Create a configurable given a config config.
Parameters
----------
config : Config
If this is empty, default values are used. If config is a
:class:`Config` instance, it will be used to configure the
instance.
parent : Configurable instance, optional
The parent Configurable instance of this object.
Notes
-----
Subclasses of Configurable must call the :meth:`__init__` method of
:class:`Configurable` *before* doing anything else and using
:func:`super`::
class MyConfigurable(Configurable):
def __init__(self, config=None):
super(MyConfigurable, self).__init__(config=config)
# Then any other code you need to finish initialization.
This ensures that instances will be configured properly.
"""
parent = kwargs.pop('parent', None)
if parent is not None:
# config is implied from parent
if kwargs.get('config', None) is None:
kwargs['config'] = parent.config
self.parent = parent
config = kwargs.pop('config', None)
if config is not None:
# We used to deepcopy, but for now we are trying to just save
# by reference. This *could* have side effects as all components
# will share config. In fact, I did find such a side effect in
# _config_changed below. If a config attribute value was a mutable type
# all instances of a component were getting the same copy, effectively
# making that a class attribute.
# self.config = deepcopy(config)
self.config = config
else:
# allow _config_default to return something
self._load_config(self.config)
# This should go second so individual keyword arguments override
# the values in config.
super(Configurable, self).__init__(**kwargs)
#-------------------------------------------------------------------------
# Static trait notifiations
#-------------------------------------------------------------------------
@classmethod
def section_names(cls):
"""return section names as a list"""
return [c.__name__ for c in reversed(cls.__mro__) if
issubclass(c, Configurable) and issubclass(cls, c)
]
def _find_my_config(self, cfg):
"""extract my config from a global Config object
will construct a Config object of only the config values that apply to me
based on my mro(), as well as those of my parent(s) if they exist.
If I am Bar and my parent is Foo, and their parent is Tim,
this will return merge following config sections, in this order::
[Bar, Foo.bar, Tim.Foo.Bar]
With the last item being the highest priority.
"""
cfgs = [cfg]
if self.parent:
cfgs.append(self.parent._find_my_config(cfg))
my_config = Config()
for c in cfgs:
for sname in self.section_names():
# Don't do a blind getattr as that would cause the config to
# dynamically create the section with name Class.__name__.
if c._has_section(sname):
my_config.merge(c[sname])
return my_config
def _load_config(self, cfg, section_names=None, traits=None):
"""load traits from a Config object"""
if traits is None:
traits = self.traits(config=True)
if section_names is None:
section_names = self.section_names()
my_config = self._find_my_config(cfg)
for name, config_value in iteritems(my_config):
if name in traits:
if isinstance(config_value, LazyConfigValue):
# ConfigValue is a wrapper for using append / update on containers
# without having to copy the
initial = getattr(self, name)
config_value = config_value.get_value(initial)
# We have to do a deepcopy here if we don't deepcopy the entire
# config object. If we don't, a mutable config_value will be
# shared by all instances, effectively making it a class attribute.
setattr(self, name, deepcopy(config_value))
def _config_changed(self, name, old, new):
"""Update all the class traits having ``config=True`` as metadata.
For any class trait with a ``config`` metadata attribute that is
``True``, we update the trait with the value of the corresponding
config entry.
"""
# Get all traits with a config metadata entry that is True
traits = self.traits(config=True)
# We auto-load config section for this class as well as any parent
# classes that are Configurable subclasses. This starts with Configurable
# and works down the mro loading the config for each section.
section_names = self.section_names()
self._load_config(new, traits=traits, section_names=section_names)
def update_config(self, config):
"""Fire the traits events when the config is updated."""
# Save a copy of the current config.
newconfig = deepcopy(self.config)
# Merge the new config into the current one.
newconfig.merge(config)
# Save the combined config as self.config, which triggers the traits
# events.
self.config = newconfig
@classmethod
def class_get_help(cls, inst=None):
"""Get the help string for this class in ReST format.
If `inst` is given, it's current trait values will be used in place of
class defaults.
"""
assert inst is None or isinstance(inst, cls)
final_help = []
final_help.append(u'%s options' % cls.__name__)
final_help.append(len(final_help[0])*u'-')
for k, v in sorted(cls.class_traits(config=True).items()):
help = cls.class_get_trait_help(v, inst)
final_help.append(help)
return '\n'.join(final_help)
@classmethod
def class_get_trait_help(cls, trait, inst=None):
"""Get the help string for a single trait.
If `inst` is given, it's current trait values will be used in place of
the class default.
"""
assert inst is None or isinstance(inst, cls)
lines = []
header = "--%s.%s=<%s>" % (cls.__name__, trait.name, trait.__class__.__name__)
lines.append(header)
if inst is not None:
lines.append(indent('Current: %r' % getattr(inst, trait.name), 4))
else:
try:
dvr = repr(trait.get_default_value())
except Exception:
dvr = None # ignore defaults we can't construct
if dvr is not None:
if len(dvr) > 64:
dvr = dvr[:61]+'...'
lines.append(indent('Default: %s' % dvr, 4))
if 'Enum' in trait.__class__.__name__:
# include Enum choices
lines.append(indent('Choices: %r' % (trait.values,)))
help = trait.get_metadata('help')
if help is not None:
help = '\n'.join(wrap_paragraphs(help, 76))
lines.append(indent(help, 4))
return '\n'.join(lines)
@classmethod
def class_print_help(cls, inst=None):
"""Get the help string for a single trait and print it."""
print(cls.class_get_help(inst))
@classmethod
def class_config_section(cls):
"""Get the config class config section"""
def c(s):
"""return a commented, wrapped block."""
s = '\n\n'.join(wrap_paragraphs(s, 78))
return '# ' + s.replace('\n', '\n# ')
# section header
breaker = '#' + '-'*78
s = "# %s configuration" % cls.__name__
lines = [breaker, s, breaker, '']
# get the description trait
desc = cls.class_traits().get('description')
if desc:
desc = desc.default_value
else:
# no description trait, use __doc__
desc = getattr(cls, '__doc__', '')
if desc:
lines.append(c(desc))
lines.append('')
parents = []
for parent in cls.mro():
# only include parents that are not base classes
# and are not the class itself
# and have some configurable traits to inherit
if parent is not cls and issubclass(parent, Configurable) and \
parent.class_traits(config=True):
parents.append(parent)
if parents:
pstr = ', '.join([ p.__name__ for p in parents ])
lines.append(c('%s will inherit config from: %s'%(cls.__name__, pstr)))
lines.append('')
for name, trait in iteritems(cls.class_traits(config=True)):
help = trait.get_metadata('help') or ''
lines.append(c(help))
lines.append('# c.%s.%s = %r'%(cls.__name__, name, trait.get_default_value()))
lines.append('')
return '\n'.join(lines)
class SingletonConfigurable(Configurable):
"""A configurable that only allows one instance.
This class is for classes that should only have one instance of itself
or *any* subclass. To create and retrieve such a class use the
:meth:`SingletonConfigurable.instance` method.
"""
_instance = None
@classmethod
def _walk_mro(cls):
"""Walk the cls.mro() for parent classes that are also singletons
For use in instance()
"""
for subclass in cls.mro():
if issubclass(cls, subclass) and \
issubclass(subclass, SingletonConfigurable) and \
subclass != SingletonConfigurable:
yield subclass
@classmethod
def clear_instance(cls):
"""unset _instance for this class and singleton parents.
"""
if not cls.initialized():
return
for subclass in cls._walk_mro():
if isinstance(subclass._instance, cls):
# only clear instances that are instances
# of the calling class
subclass._instance = None
@classmethod
def instance(cls, *args, **kwargs):
"""Returns a global instance of this class.
This method create a new instance if none have previously been created
and returns a previously created instance is one already exists.
The arguments and keyword arguments passed to this method are passed
on to the :meth:`__init__` method of the class upon instantiation.
Examples
--------
Create a singleton class using instance, and retrieve it::
>>> from IPython.config.configurable import SingletonConfigurable
>>> class Foo(SingletonConfigurable): pass
>>> foo = Foo.instance()
>>> foo == Foo.instance()
True
Create a subclass that is retrived using the base class instance::
>>> class Bar(SingletonConfigurable): pass
>>> class Bam(Bar): pass
>>> bam = Bam.instance()
>>> bam == Bar.instance()
True
"""
# Create and save the instance
if cls._instance is None:
inst = cls(*args, **kwargs)
# Now make sure that the instance will also be returned by
# parent classes' _instance attribute.
for subclass in cls._walk_mro():
subclass._instance = inst
if isinstance(cls._instance, cls):
return cls._instance
else:
raise MultipleInstanceError(
'Multiple incompatible subclass instances of '
'%s are being created.' % cls.__name__
)
@classmethod
def initialized(cls):
"""Has an instance been created?"""
return hasattr(cls, "_instance") and cls._instance is not None
class LoggingConfigurable(Configurable):
"""A parent class for Configurables that log.
Subclasses have a log trait, and the default behavior
is to get the logger from the currently running Application.
"""
log = Instance('logging.Logger')
def _log_default(self):
from IPython.utils import log
return log.get_logger()