check we don't get selection ambiguity: if yes, log error in production env, raise in other modes
"""
* the vregistry handle various type of objects interacting
together. The vregistry handle registration of dynamically loaded
objects and provide a convenient api access to those objects
according to a context
* to interact with the vregistry, object should inherit from the
VObject abstract class
* the registration procedure is delegated to a registerer. Each
registerable vobject must defines its registerer class using the
__registerer__ attribute. A registerer is instantianted at
registration time after what the instance is lost
* the selection procedure has been generalized by delegating to a
selector, which is responsible to score the vobject according to the
current state (req, rset, row, col). At the end of the selection, if
a vobject class has been found, an instance of this class is
returned. The selector is instantiated at vobject registration
:organization: Logilab
:copyright: 2001-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""
__docformat__ = "restructuredtext en"
import sys
from os import listdir, stat
from os.path import dirname, join, realpath, split, isdir
from logging import getLogger
from cubicweb import CW_SOFTWARE_ROOT, set_log_methods
from cubicweb import RegistryNotFound, ObjectNotFound, NoSelectableObject
class vobject_helper(object):
"""object instantiated at registration time to help a wrapped
VObject subclass
"""
def __init__(self, registry, vobject):
self.registry = registry
self.vobject = vobject
self.config = registry.config
self.schema = registry.schema
class registerer(vobject_helper):
"""do whatever is needed at registration time for the wrapped
class, according to current application schema and already
registered objects of the same kind (i.e. same registry name and
same id).
The wrapped class may be skipped, some previously selected object
may be kicked out... After whatever works needed, if the object or
a transformed object is returned, it will be added to previously
registered objects.
"""
def __init__(self, registry, vobject):
super(registerer, self).__init__(registry, vobject)
self.kicked = set()
def do_it_yourself(self, registered):
raise NotImplementedError(str(self.vobject))
def kick(self, registered, kicked):
self.debug('kicking vobject %s', kicked)
registered.remove(kicked)
self.kicked.add(kicked.classid())
def skip(self):
self.debug('no schema compat, skipping %s', self.vobject)
def selector(cls, *args, **kwargs):
"""selector is called to help choosing the correct object for a
particular request and result set by returning a score.
it must implement a .score_method taking a request, a result set and
optionaly row and col arguments which return an int telling how well
the wrapped class apply to the given request and result set. 0 score
means that it doesn't apply.
rset may be None. If not, row and col arguments may be optionally
given if the registry is scoring a given row or a given cell of
the result set (both row and col are int if provided).
"""
raise NotImplementedError(cls)
class autoselectors(type):
"""implements __selectors__ / __select__ compatibility layer so that:
__select__ = chainall(classmethod(A, B, C))
can be replaced by something like:
__selectors__ = (A, B, C)
"""
def __new__(mcs, name, bases, classdict):
if '__select__' in classdict and '__selectors__' in classdict:
raise TypeError("__select__ and __selectors__ "
"can't be used together")
if '__select__' not in classdict and '__selectors__' in classdict:
selectors = classdict['__selectors__']
classdict['__select__'] = classmethod(chainall(*selectors))
return super(autoselectors, mcs).__new__(mcs, name, bases, classdict)
def __setattr__(self, attr, value):
if attr == '__selectors__':
self.__select__ = classmethod(chainall(*value))
super(autoselectors, self).__setattr__(attr, value)
class VObject(object):
"""visual object, use to be handled somehow by the visual components
registry.
The following attributes should be set on concret vobject subclasses:
:__registry__:
name of the registry for this object (string like 'views',
'templates'...)
:id:
object's identifier in the registry (string like 'main',
'primary', 'folder_box')
:__registerer__:
registration helper class
:__select__:
selection helper function
:__selectors__:
tuple of selectors to be chained
(__select__ and __selectors__ are mutually exclusive)
Moreover, the `__abstract__` attribute may be set to True to indicate
that a vobject is abstract and should not be registered
"""
__metaclass__ = autoselectors
# necessary attributes to interact with the registry
id = None
__registry__ = None
__registerer__ = None
__select__ = None
@classmethod
def registered(cls, registry):
"""called by the registry when the vobject has been registered.
It must return the object that will be actually registered (this
may be the right hook to create an instance for example). By
default the vobject is returned without any transformation.
"""
return cls
@classmethod
def selected(cls, *args, **kwargs):
"""called by the registry when the vobject has been selected.
It must return the object that will be actually returned by the
.select method (this may be the right hook to create an
instance for example). By default the selected object is
returned without any transformation.
"""
return cls
@classmethod
def classid(cls):
"""returns a unique identifier for the vobject"""
return '%s.%s' % (cls.__module__, cls.__name__)
class VRegistry(object):
"""class responsible to register, propose and select the various
elements used to build the web interface. Currently, we have templates,
views, actions and components.
"""
def __init__(self, config):#, cache_size=1000):
self.config = config
# dictionnary of registry (themself dictionnary) by name
self._registries = {}
self._lastmodifs = {}
def reset(self):
self._registries = {}
self._lastmodifs = {}
def __getitem__(self, key):
return self._registries[key]
def get(self, key, default=None):
return self._registries.get(key, default)
def items(self):
return self._registries.items()
def values(self):
return self._registries.values()
def __contains__(self, key):
return key in self._registries
def register_vobject_class(self, cls, _kicked=set()):
"""handle vobject class registration
vobject class with __abstract__ == True in their local dictionnary or
with a name starting starting by an underscore are not registered.
Also a vobject class needs to have __registry__ and id attributes set
to a non empty string to be registered.
Registration is actually handled by vobject's registerer.
"""
if (cls.__dict__.get('__abstract__') or cls.__name__[0] == '_'
or not cls.__registry__ or not cls.id):
return
# while reloading a module :
# if cls was previously kicked, it means that there is a more specific
# vobject defined elsewhere re-registering cls would kick it out
if cls.classid() in _kicked:
self.debug('not re-registering %s because it was previously kicked',
cls.classid())
else:
regname = cls.__registry__
if cls.id in self.config['disable-%s' % regname]:
return
registry = self._registries.setdefault(regname, {})
vobjects = registry.setdefault(cls.id, [])
registerer = cls.__registerer__(self, cls)
cls = registerer.do_it_yourself(vobjects)
#_kicked |= registerer.kicked
if cls:
vobject = cls.registered(self)
try:
vname = vobject.__name__
except AttributeError:
vname = vobject.__class__.__name__
self.debug('registered vobject %s in registry %s with id %s',
vname, cls.__registry__, cls.id)
vobjects.append(vobject)
def unregister_module_vobjects(self, modname):
"""removes registered objects coming from a given module
returns a dictionnary classid/class of all classes that will need
to be updated after reload (i.e. vobjects referencing classes defined
in the <modname> module)
"""
unregistered = {}
# browse each registered object
for registry, objdict in self.items():
for oid, objects in objdict.items():
for obj in objects[:]:
objname = obj.classid()
# if the vobject is defined in this module, remove it
if objname.startswith(modname):
unregistered[objname] = obj
objects.remove(obj)
self.debug('unregistering %s in %s registry',
objname, registry)
# if not, check if the vobject can be found in baseclasses
# (because we also want subclasses to be updated)
else:
if not isinstance(obj, type):
obj = obj.__class__
for baseclass in obj.__bases__:
if hasattr(baseclass, 'classid'):
baseclassid = baseclass.classid()
if baseclassid.startswith(modname):
unregistered[baseclassid] = baseclass
# update oid entry
if objects:
objdict[oid] = objects
else:
del objdict[oid]
return unregistered
def update_registered_subclasses(self, oldnew_mapping):
"""updates subclasses of re-registered vobjects
if baseviews.PrimaryView is changed, baseviews.py will be reloaded
automatically and the new version of PrimaryView will be registered.
But all existing subclasses must also be notified of this change, and
that's what this method does
:param oldnew_mapping: a dict mapping old version of a class to
the new version
"""
# browse each registered object
for objdict in self.values():
for objects in objdict.values():
for obj in objects:
if not isinstance(obj, type):
obj = obj.__class__
# build new baseclasses tuple
newbases = tuple(oldnew_mapping.get(baseclass, baseclass)
for baseclass in obj.__bases__)
# update obj's baseclasses tuple (__bases__) if needed
if newbases != obj.__bases__:
self.debug('updating %s.%s base classes',
obj.__module__, obj.__name__)
obj.__bases__ = newbases
def registry(self, name):
"""return the registry (dictionary of class objects) associated to
this name
"""
try:
return self._registries[name]
except KeyError:
raise RegistryNotFound(name), None, sys.exc_info()[-1]
def registry_objects(self, name, oid=None):
"""returns objects registered with the given oid in the given registry.
If no oid is given, return all objects in this registry
"""
registry = self.registry(name)
if oid:
try:
return registry[oid]
except KeyError:
raise ObjectNotFound(oid), None, sys.exc_info()[-1]
else:
result = []
for objs in registry.values():
result += objs
return result
def select(self, vobjects, *args, **kwargs):
"""return an instance of the most specific object according
to parameters
raise NoSelectableObject if not object apply
"""
score, winners = 0, []
for vobject in vobjects:
vobjectscore = vobject.__select__(*args, **kwargs)
if vobjectscore > score:
score, winners = vobjectscore, [vobject]
elif vobjectscore > 0 and vobjectscore == score:
winners.append(vobject)
if not winners:
raise NoSelectableObject('args: %s\nkwargs: %s %s'
% (args, kwargs.keys(), [repr(v) for v in vobjects]))
if len(winners) > 1:
if self.config.mode == 'installed':
self.error('select ambiguity, args: %s\nkwargs: %s %s',
args, kwargs.keys(), [repr(v) for v in winners])
else:
raise Exception('select ambiguity, args: %s\nkwargs: %s %s'
% (args, kwargs.keys(), [repr(v) for v in winners]))
winner = winners[0]
# return the result of the .selected method of the vobject
return winner.selected(*args, **kwargs)
def possible_objects(self, registry, *args, **kwargs):
"""return an iterator on possible objects in a registry for this result set
actions returned are classes, not instances
"""
for vobjects in self.registry(registry).values():
try:
yield self.select(vobjects, *args, **kwargs)
except NoSelectableObject:
continue
def select_object(self, registry, cid, *args, **kwargs):
"""return the most specific component according to the resultset"""
return self.select(self.registry_objects(registry, cid), *args, **kwargs)
def object_by_id(self, registry, cid, *args, **kwargs):
"""return the most specific component according to the resultset"""
objects = self[registry][cid]
assert len(objects) == 1, objects
return objects[0].selected(*args, **kwargs)
# intialization methods ###################################################
def register_objects(self, path, force_reload=None):
if force_reload is None:
force_reload = self.config.mode == 'dev'
elif not force_reload:
# force_reload == False usually mean modules have been reloaded
# by another connection, so we want to update the registry
# content even if there has been no module content modification
self.reset()
# need to clean sys.path this to avoid import confusion pb (i.e.
# having the same module loaded as 'cubicweb.web.views' subpackage and
# as views' or 'web.views' subpackage
# this is mainly for testing purpose, we should'nt need this in
# production environment
for webdir in (join(dirname(realpath(__file__)), 'web'),
join(dirname(__file__), 'web')):
if webdir in sys.path:
sys.path.remove(webdir)
if CW_SOFTWARE_ROOT in sys.path:
sys.path.remove(CW_SOFTWARE_ROOT)
# load views from each directory in the application's path
change = False
for fileordirectory in path:
if isdir(fileordirectory):
if self.read_directory(fileordirectory, force_reload):
change = True
else:
directory, filename = split(fileordirectory)
if self.load_file(directory, filename, force_reload):
change = True
if change:
for registry, objects in self.items():
self.debug('available in registry %s: %s', registry,
sorted(objects))
return change
def read_directory(self, directory, force_reload=False):
"""read a directory and register available views"""
modified_on = stat(realpath(directory))[-2]
# only read directory if it was modified
_lastmodifs = self._lastmodifs
if directory in _lastmodifs and modified_on <= _lastmodifs[directory]:
return False
self.info('loading directory %s', directory)
for filename in listdir(directory):
if filename[-3:] == '.py':
try:
self.load_file(directory, filename, force_reload)
except OSError:
# this typically happens on emacs backup files (.#foo.py)
self.warning('Unable to load file %s. It is likely to be a backup file',
filename)
except Exception, ex:
if self.config.mode in ('dev', 'test'):
raise
self.exception('%r while loading file %s', ex, filename)
_lastmodifs[directory] = modified_on
return True
def load_file(self, directory, filename, force_reload=False):
"""load visual objects from a python file"""
from logilab.common.modutils import load_module_from_modpath, modpath_from_file
filepath = join(directory, filename)
modified_on = stat(filepath)[-2]
modpath = modpath_from_file(join(directory, filename))
modname = '.'.join(modpath)
unregistered = {}
_lastmodifs = self._lastmodifs
if filepath in _lastmodifs:
# only load file if it was modified
if modified_on <= _lastmodifs[filepath]:
return
else:
# if it was modified, unregister all exisiting objects
# from this module, and keep track of what was unregistered
unregistered = self.unregister_module_vobjects(modname)
# load the module
module = load_module_from_modpath(modpath, use_sys=not force_reload)
registered = self.load_module(module)
# if something was unregistered, we need to update places where it was
# referenced
if unregistered:
# oldnew_mapping = {}
oldnew_mapping = dict((unregistered[name], registered[name])
for name in unregistered if name in registered)
self.update_registered_subclasses(oldnew_mapping)
_lastmodifs[filepath] = modified_on
return True
def load_module(self, module):
registered = {}
self.info('loading %s', module)
for objname, obj in vars(module).items():
if objname.startswith('_'):
continue
self.load_ancestors_then_object(module.__name__, registered, obj)
return registered
def load_ancestors_then_object(self, modname, registered, obj):
# skip imported classes
if getattr(obj, '__module__', None) != modname:
return
# skip non registerable object
try:
if not issubclass(obj, VObject):
return
except TypeError:
return
objname = '%s.%s' % (modname, obj.__name__)
if objname in registered:
return
registered[objname] = obj
for parent in obj.__bases__:
self.load_ancestors_then_object(modname, registered, parent)
self.load_object(obj)
def load_object(self, obj):
try:
self.register_vobject_class(obj)
except Exception, ex:
if self.config.mode in ('test', 'dev'):
raise
self.exception('vobject %s registration failed: %s', obj, ex)
# init logging
set_log_methods(VObject, getLogger('cubicweb'))
set_log_methods(VRegistry, getLogger('cubicweb.registry'))
set_log_methods(registerer, getLogger('cubicweb.registration'))
# advanced selector building functions ########################################
def chainall(*selectors):
"""return a selector chaining given selectors. If one of
the selectors fail, selection will fail, else the returned score
will be the sum of each selector'score
"""
assert selectors
def selector(cls, *args, **kwargs):
score = 0
for selector in selectors:
partscore = selector(cls, *args, **kwargs)
if not partscore:
return 0
score += partscore
return score
return selector
def chainfirst(*selectors):
"""return a selector chaining given selectors. If all
the selectors fail, selection will fail, else the returned score
will be the first non-zero selector score
"""
assert selectors
def selector(cls, *args, **kwargs):
for selector in selectors:
partscore = selector(cls, *args, **kwargs)
if partscore:
return partscore
return 0
return selector