[source storage] refactor source sql generation and results handling to allow repository side callbacks
for instance with the BytesFileSystemStorage, before this change:
* fspath, _fsopen function were stored procedures executed on the database
-> files had to be available both on the repository *and* the database host
* we needed implementation for each handled database
Now, those function are python callbacks executed when necessary on the
repository side, on data comming from the database.
The litle cons are:
* you can't do anymore restriction on mapped attributes
* you can't write queries which will return in the same rset column
some mapped attributes (or not mapped the same way) / some not
This seems much acceptable since:
* it's much more easy to handle when you start having the db on another host
than the repo
* BFSS works seemlessly on any backend now
* you don't bother that much about the cons (at least in the bfss case):
you usually don't do any restriction on Bytes...
Bonus points: BFSS is more efficient (no queries under the cover as it
was done in the registered procedure) and we have a much nicer/efficient
fspath implementation.
IMO, that rocks :D
"""CubicWeb is a generic framework to quickly build applications which describes
relations between entitites.
:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: Library General Public License version 2 - http://www.gnu.org/licenses
"""
__docformat__ = "restructuredtext en"
import __builtin__
# '_' is available in builtins to mark internationalized string but should
# not be used to do the actual translation
if not hasattr(__builtin__, '_'):
__builtin__._ = unicode
CW_SOFTWARE_ROOT = __path__[0]
import sys, os, logging
from StringIO import StringIO
from logilab.common.logging_ext import set_log_methods
if os.environ.get('APYCOT_ROOT'):
logging.basicConfig(level=logging.CRITICAL)
else:
logging.basicConfig()
from cubicweb.__pkginfo__ import version as __version__
set_log_methods(sys.modules[__name__], logging.getLogger('cubicweb'))
# make all exceptions accessible from the package
from cubicweb._exceptions import *
# convert eid to the right type, raise ValueError if it's not a valid eid
typed_eid = int
#def log_thread(f, w, a):
# print f.f_code.co_filename, f.f_code.co_name
#import threading
#threading.settrace(log_thread)
class Binary(StringIO):
"""customize StringIO to make sure we don't use unicode"""
def __init__(self, buf=''):
assert isinstance(buf, (str, buffer)), \
"Binary objects must use raw strings, not %s" % buf.__class__
StringIO.__init__(self, buf)
def write(self, data):
assert isinstance(data, (str, buffer)), \
"Binary objects must use raw strings, not %s" % data.__class__
StringIO.write(self, data)
# use this dictionary to rename entity types while keeping bw compat
ETYPE_NAME_MAP = {}
# XXX cubic web cube migration map. See if it's worth keeping this mecanism
# to help in cube renaming
CW_MIGRATION_MAP = {}
def neg_role(role):
if role == 'subject':
return 'object'
return 'subject'
def role(obj):
try:
return obj.role
except AttributeError:
return neg_role(obj.target)
def target(obj):
try:
return obj.target
except AttributeError:
return neg_role(obj.role)
class CubicWebEventManager(object):
"""simple event / callback manager.
Typical usage to register a callback::
>>> from cubicweb import CW_EVENT_MANAGER
>>> CW_EVENT_MANAGER.bind('after-registry-reload', mycallback)
Typical usage to emit an event::
>>> from cubicweb import CW_EVENT_MANAGER
>>> CW_EVENT_MANAGER.emit('after-registry-reload')
emit() accepts an additional context parameter that will be passed
to the callback if specified (and only in that case)
"""
def __init__(self):
self.callbacks = {}
def bind(self, event, callback, *args, **kwargs):
self.callbacks.setdefault(event, []).append( (callback, args, kwargs) )
def emit(self, event, context=None):
for callback, args, kwargs in self.callbacks.get(event, ()):
if context is None:
callback(*args, **kwargs)
else:
callback(context, *args, **kwargs)
CW_EVENT_MANAGER = CubicWebEventManager()
def onevent(event):
"""decorator to ease event / callback binding
>>> from cubicweb import onevent
>>> @onevent('before-registry-reload')
... def mycallback():
... print 'hello'
...
>>>
"""
def _decorator(func):
CW_EVENT_MANAGER.bind(event, func)
return func
return _decorator