Storage

A storage is a component dedicated to store contents. It behaves like a container and provides the interface dolmen.storage.IStorage.

Out of the box, two IStorage components are available, based on ZODB BTrees:

>>> from dolmen.storage import IStorage
>>> from dolmen.storage import container
>>> from zope.container.interfaces import IContainer

>>> otree = container.OOBTreeStorage()
>>> itree = container.IOBTreeStorage()

>>> IStorage.extends(IContainer)
True

>>> from zope.interface import verify
>>> verify.verifyObject(IStorage, otree)
True
>>> verify.verifyObject(IStorage, itree)
True

Delegated storage

A delegated storage is a component behaving like a Storage but delegating all the container-level methods to a storage attribute:

>>> from dolmen.storage import IDelegatedStorage, DelegatedStorage

>>> class MyStorage(DelegatedStorage):
...     def __init__(self):
...         self.storage = container.OOBTreeStorage()
>>> container = MyStorage()

>>> verify.verifyObject(IDelegatedStorage, container)
True

>>> container['manfred'] = 'mammoth'
>>> 'manfred' in container
True
>>> 'manfred' in container.storage
True

The storage attribute has to be a valid IStorage:

>>> class FailingStorage(DelegatedStorage):
...     def __init__(self):
...         self.storage = list()
>>> container = FailingStorage()
Traceback (most recent call last):
...
SchemaNotProvided

Annotation Storage

The annotation storage provides a way to delegate the storage in an annotation container:

>>> import grokcore.component as grok
>>> from dolmen.storage import AnnotationStorage
>>> from zope.annotation.interfaces import IAnnotations
>>> from zope.annotation.interfaces import IAttributeAnnotatable

>>> class Mammoth(object):
...    '''A furry creature
...    '''
...    grok.implements(IAttributeAnnotatable)

>>> class NamedStorage(AnnotationStorage):
...    grok.name('some.name')

>>> manfred = Mammoth()
>>> named_storage = NamedStorage(manfred)
>>> IDelegatedStorage.providedBy(named_storage)
True

>>> named_storage['test'] = 'This is a simple test'
>>> list(named_storage.values())
['This is a simple test']

>>> annotations = IAnnotations(manfred).get("some.name")
>>> annotations == named_storage.storage
True
>>> annotations['test']
'This is a simple test'

Annotation property

The annotation property allows a direct access to an annotation storage or value via a FieldProperty-like property:

>>> from zope.schema import TextLine
>>> from zope.interface import Interface
>>> from dolmen.storage import AnnotationProperty

>>> class WildMammoth(object):
...    '''A furry creature
...    '''
...    grok.implements(IAttributeAnnotatable)

>>> class IRidingMount(Interface):
...    rider = TextLine(title=u'Name of the rider', default=None)

>>> class MammothRiding(grok.Adapter):
...    rider = AnnotationProperty(IRidingMount['rider'])

>>> wooly = WildMammoth()
>>> annotator = MammothRiding(wooly)
>>> annotator.rider = u'Grok'

>>> IAnnotations(wooly).get("rider")
u'Grok'

0.4 (2010-12-23)

• The delegated AnnotationStorage now uses a zope.location.LocationProxy to avoid writting the location information directly on the storage object. This removes all related read/write conflicts.

0.3 (2010-02-21)

• Cleaned all dependencies. Now, dolmen.storage is 100% zope.app free.

0.2 (2009-12-26)

• ZTK compatibility imports change.

0.1 (2009-10-19)

• Initial release