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Move with statement so history db cache is written out in one transaction (two if output history is being logged).
Move with statement so history db cache is written out in one transaction (two if output history is being logged).

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configurable.py
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#!/usr/bin/env python
# encoding: utf-8
"""
A base class for objects that are configurable.
Authors:
* Brian Granger
* Fernando Perez
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2010 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from copy import deepcopy
import datetime
from weakref import WeakValueDictionary
from IPython.utils.importstring import import_item
from loader import Config
from IPython.utils.traitlets import HasTraits, Instance
#-----------------------------------------------------------------------------
# Helper classes for Configurables
#-----------------------------------------------------------------------------
class ConfigurableError(Exception):
pass
#-----------------------------------------------------------------------------
# Configurable implementation
#-----------------------------------------------------------------------------
class Configurable(HasTraits):
config = Instance(Config,(),{})
created = None
def __init__(self, **kwargs):
"""Create a conigurable 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.
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)
# Then any other code you need to finish initialization.
This ensures that instances will be configured properly.
"""
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
# This should go second so individual keyword arguments override
# the values in config.
super(Configurable, self).__init__(**kwargs)
self.created = datetime.datetime.now()
#-------------------------------------------------------------------------
# Static trait notifiations
#-------------------------------------------------------------------------
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 = [cls.__name__ for cls in \
reversed(self.__class__.__mro__) if
issubclass(cls, Configurable) and issubclass(self.__class__, cls)]
for sname in section_names:
# Don't do a blind getattr as that would cause the config to
# dynamically create the section with name self.__class__.__name__.
if new._has_section(sname):
my_config = new[sname]
for k, v in traits.iteritems():
# Don't allow traitlets with config=True to start with
# uppercase. Otherwise, they are confused with Config
# subsections. But, developers shouldn't have uppercase
# attributes anyways! (PEP 6)
if k[0].upper()==k[0] and not k.startswith('_'):
raise ConfigurableError('Configurable traitlets with '
'config=True must start with a lowercase so they are '
'not confused with Config subsections: %s.%s' % \
(self.__class__.__name__, k))
try:
# Here we grab the value from the config
# If k has the naming convention of a config
# section, it will be auto created.
config_value = my_config[k]
except KeyError:
pass
else:
# print "Setting %s.%s from %s.%s=%r" % \
# (self.__class__.__name__,k,sname,k,config_value)
# 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, k, deepcopy(config_value))