ftw.dictstorage 1.3.0 on PyPI

Introduction

This package provides a layer for storing key/value pairs. The storage can be configured dynamically by providing a IConfig adapter of the context on which the dict storage is used.

Examples

The adapter defaults to using a non-persistent dict:

>>> from ftw.dictstorage.interfaces import IDictStorage

>>> context = layer['example_context']
>>> print context
<ftw.dictstorage.testing.ExampleContext object at ...>

>>> storage = IDictStorage(context)
>>> storage['key'] = 'value'
>>> print storage['key']
value

>>> print storage.storage
{'key': 'value'}

>>> print IDictStorage(context).storage
{}

For configuring a custom storage, implement your own IConfig which uses custom IDictStorage:

>>> from ftw.dictstorage.interfaces import IConfig
>>> from ftw.dictstorage.base import DictStorage
>>> from zope.component import provideAdapter, adapts
>>> from zope.interface import Interface, alsoProvides, implements

>>> context = layer['example_context']
>>> class IMyContext(Interface):
...     pass
>>> alsoProvides(context, IMyContext)

>>> class ContextStorageConfig(object):
...     implements(IConfig)
...     adapts(IMyContext)
...
...     def __init__(self, context):
...         self.context = context
...
...     def get_storage(self):
...         if not hasattr(self.context, '_dictstorage'):
...             self.context._dictstorage = {}
...         return self.context._dictstorage
>>> provideAdapter(ContextStorageConfig)

>>> class ContextDictStorage(DictStorage):
...     implements(IDictStorage)
...     adapts(IMyContext, IConfig)
...
...     def __init__(self, context, config):
...         self.context = context
...         self.config = config
...         self._storage = config.get_storage()
...
...     @property
...     def storage(self):
...         return self._storage
...
>>> provideAdapter(ContextDictStorage)

>>> storage = IDictStorage(context)
>>> storage['foo'] = 'bar'
>>> print storage['foo']
bar

>>> print context._dictstorage
{'foo': 'bar'}

>>> print IDictStorage(context)['foo']
bar