z3c.proxy 0.6.1

Container proxy implementation for Zope3

This package provides a proxy container implementation for Zope3.

Contents

• z3c.proxy

  • ObjectMover

  • ObjectCopier

  • ProxyAwareContainerItemRenamer

• CHANGES

  • 0.6.1 (2010-08-23)

  • 0.6.0 (2010-08-23)

  • 0.5.0 (2008-04-12)

z3c.proxy

We can proxy a regular container derived from zope’s btree container for example:

>>> from zope.container.interfaces import IContainer
>>> from zope.container.btree import BTreeContainer
>>> container = BTreeContainer()
>>> container.__name__, container.__parent__ = u'c1', u'p1'

>>> from z3c.proxy import interfaces
>>> from z3c.proxy.container import LocationProxy
>>> from z3c.proxy.container import ContainerLocationProxy
>>> proxy = ContainerLocationProxy(container)

The name and the parent of the proxy is None. The proxy provides IContainer:

>>> proxy.__name__ is None
True
>>> proxy.__parent__ is None
True
>>> IContainer.providedBy(proxy)
True
>>> interfaces.IContainerLocationProxy.providedBy(proxy)
True

First we check the empty proxy:

>>> proxy['x']
Traceback (most recent call last):
...
KeyError: 'x'

>>> 'x' in proxy
False

>>> proxy.has_key('x')
0

>>> [key for key in proxy.keys()]
[]

>>> [item for item in proxy.items()]
[]

>>> proxy.get('x') is None
True

>>> iterator = iter(proxy)
>>> iterator.next()
Traceback (most recent call last):
...
StopIteration

>>> proxy.values()
[]

>>> len(proxy)
0

>>> del proxy['x']
Traceback (most recent call last):
...
KeyError: 'x'

>>> from zope.container.contained import Contained
>>> proxy['x'] = x = Contained()

Now we added our first item. This item should be added to the container. Its name will be x and its parent is the container itself:

>>> x is container['x']
True

>>> x.__name__
u'x'

>>> x.__parent__ is container
True

If we lookup ‘x’ within the proxy we do not get the blank ‘x’ but rather the proxied ‘x’. The proxy is not ‘x’ but only equal to ‘x’:

>>> x is proxy['x']
False

>>> x == proxy['x']
True

>>> x1 = proxy['x']
>>> from zope.proxy import isProxy
>>> isProxy(x1)
True

>>> isinstance(x1, LocationProxy)
True

The proxied ‘x’ has still the same name but not the same parent:

>>> x1.__name__
u'x'

>>> x1.__parent__ is container
False

>>> x1.__parent__ is proxy
True

If we add a second item to the container, it should appear in the proxy, too. But this item is proxied as container location proxy:

>>> container['y'] = y = BTreeContainer()
>>> y1 = proxy['y']
>>> y1 is y
False

>>> y1 == y
True

>>> isinstance(y1, ContainerLocationProxy)
True

The container location proxy is able to proxy the location of nested objects:

>>> proxy['y']['z'] = z = Contained()
>>> container['y']['z'] is z
True

>>> z1 = y1['z']
>>> z1 is z
False

>>> z1 == z
True

>>> isinstance(z1, LocationProxy)
True

>>> z1.__parent__ is y1
True

Finaly we check all other methods of the proxy:

>>> 'x' in proxy
True

>>> proxy.has_key('x')
1

>>> keys = [key for key in proxy.keys()]; keys.sort(); keys
[u'x', u'y']

>>> items = [item for item in proxy.items()]; items.sort()
>>> items == [(u'x', x), (u'y', y)]
True

>>> proxy.get('x') == x
True

>>> iterator = iter(proxy)
>>> iterator.next() in proxy
True

>>> iterator.next() in proxy
True

>>> iterator.next()
Traceback (most recent call last):
...
StopIteration

>>> values = proxy.values(); values.sort();
>>> x in values, y in values
(True, True)

>>> len(proxy)
2

>>> del proxy['x']
>>> 'x' in proxy
False

ObjectMover

To use an object mover, pass a contained object to the class. The contained object should implement IContained. It should be contained in a container that has an adapter to INameChooser.

Setup test container and proxies:

>>> from zope.interface import implements
>>> from zope.container.interfaces import INameChooser
>>> from zope.copypastemove import ExampleContainer
>>> from z3c.proxy.container import ProxyAwareObjectMover

>>> class ContainerLocationProxyStub(ContainerLocationProxy):
...
...     implements(INameChooser)
...
...     def chooseName(self, name, ob):
...        while name in self:
...            name += '_'
...        return name

>>> container = ExampleContainer()
>>> container2 = ExampleContainer()

>>> ob = Contained()
>>> proxy = ContainerLocationProxyStub(container)
>>> proxy[u'foo'] = ob
>>> ob = proxy[u'foo']
>>> mover = ProxyAwareObjectMover(ob)

In addition to moving objects, object movers can tell you if the object is movable:

>>> mover.moveable()
1

which, at least for now, they always are. A better question to ask is whether we can move to a particular container. Right now, we can always move to a container of the same class:

>>> proxy2 = ContainerLocationProxyStub(container2)
>>> mover.moveableTo(proxy2)
1

>>> mover.moveableTo({})
Traceback (most recent call last):
...
TypeError: Container is not a valid Zope container.

Of course, once we’ve decided we can move an object, we can use the mover to do so:

>>> mover.moveTo(proxy2)
u'foo'

>>> list(proxy)
[]

>>> list(proxy2)
[u'foo']

>>> ob = proxy2[u'foo']
>>> ob.__parent__ is proxy2
True

We can also specify a name:

>>> mover.moveTo(proxy2, u'bar')
u'bar'

>>> list(proxy2)
[u'bar']

>>> ob = proxy2[u'bar']
>>> ob.__parent__ is proxy2
True

>>> ob.__name__
u'bar'

But we may not use the same name given, if the name is already in use:

>>> proxy2[u'splat'] = 1
>>> mover.moveTo(proxy2, u'splat')
u'splat_'

>>> l = list(proxy2)
>>> l.sort()
>>> l
[u'splat', u'splat_']

>>> ob = proxy2[u'splat_']
>>> ob.__name__
u'splat_'

If we try to move to an invalid container, we’ll get an error:

>>> mover.moveTo({})
Traceback (most recent call last):
...
TypeError: Container is not a valid Zope container.

ObjectCopier

To use an object copier, pass a contained object to the class. The contained object should implement IContained. It should be contained in a container that has an adapter to INameChooser.

Setup test container and proxies:

>>> from z3c.proxy.container import ProxyAwareObjectCopier
>>> class ContainerLocationProxyStub(ContainerLocationProxy):
...
...     implements(INameChooser)
...
...     def chooseName(self, name, ob):
...        while name in self:
...            name += '_'
...        return name

>>> container = ExampleContainer()
>>> container2 = ExampleContainer()

>>> proxy = ContainerLocationProxyStub(container)
>>> proxy[u'foo'] = ob = Contained()
>>> ob = proxy[u'foo']
>>> copier = ProxyAwareObjectCopier(ob)

In addition to moving objects, object copiers can tell you if the object is movable:

>>> copier.copyable()
1

which, at least for now, they always are. A better question to ask is whether we can copy to a particular container. Right now, we can always copy to a container of the same class:

>>> proxy2 = ContainerLocationProxyStub(container2)
>>> copier.copyableTo(proxy2)
1

>>> copier.copyableTo({})
Traceback (most recent call last):
...
TypeError: Container is not a valid Zope container.

Of course, once we’ve decided we can copy an object, we can use the copier to do so:

>>> copier.copyTo(proxy2)
u'foo'

>>> list(proxy)
[u'foo']

>>> list(proxy2)
[u'foo']

>>> ob.__parent__ is proxy
1

>>> proxy2[u'foo'] is ob
0

>>> proxy2[u'foo'].__parent__ is proxy2
1

>>> proxy2[u'foo'].__name__
u'foo'

We can also specify a name:

>>> copier.copyTo(proxy2, u'bar')
u'bar'

>>> l = list(proxy2)
>>> l.sort()
>>> l
[u'bar', u'foo']

>>> ob.__parent__ is proxy
1

>>> proxy2[u'bar'] is ob
0

>>> proxy2[u'bar'].__parent__ is proxy2
1

>>> proxy2[u'bar'].__name__
u'bar'

But we may not use the same name given, if the name is already in use:

>>> copier.copyTo(proxy2, u'bar')
u'bar_'

>>> l = list(proxy2)
>>> l.sort()
>>> l
[u'bar', u'bar_', u'foo']

>>> proxy2[u'bar_'].__name__
u'bar_'

If we try to copy to an invalid container, we’ll get an error:

>>> copier.copyTo({})
Traceback (most recent call last):
...
TypeError: Container is not a valid Zope container.

ProxyAwareContainerItemRenamer

This adapter uses IObjectMover to move an item within the same container to a different name. We need to first setup an adapter for IObjectMover:

Setup test container and proxies:

>>> from zope.container.sample import SampleContainer
>>> from zope.copypastemove import ContainerItemRenamer
>>> from zope.copypastemove import IObjectMover
>>> from z3c.proxy.container import ProxyAwareContainerItemRenamer

>>> import zope.component
>>> from zope.container.interfaces import IContained
>>> zope.component.provideAdapter(ProxyAwareObjectMover, [IContained],
...     IObjectMover)

>>> class ContainerLocationProxyStub(ContainerLocationProxy):
...
...     implements(INameChooser)
...
...     def chooseName(self, name, ob):
...        while name in self:
...            name += '_'
...        return name

To rename an item in a container, instantiate a ContainerItemRenamer with the container:

>>> container = SampleContainer()
>>> proxy = ContainerLocationProxyStub(container)
>>> renamer = ProxyAwareContainerItemRenamer(container)

For this example, we’ll rename an item ‘foo’:

>>> from z3c.proxy.container import _unproxy
>>> foo = Contained()
>>> proxy['foo'] = foo
>>> proxy['foo'] == _unproxy(foo)
True

to ‘bar’:

>>> renamer.renameItem('foo', 'bar')
>>> proxy['foo'] is foo
Traceback (most recent call last):
KeyError: 'foo'

>>> proxy['bar'] == _unproxy(foo)
True

If the item being renamed isn’t in the container, a NotFoundError is raised:

>>> renamer.renameItem('foo', 'bar') # doctest:+ELLIPSIS
Traceback (most recent call last):
ItemNotFoundError: (<...SampleContainer...>, 'foo')

If the new item name already exists, a DuplicationError is raised:

>>> renamer.renameItem('bar', 'bar')
Traceback (most recent call last):
DuplicationError: bar is already in use

CHANGES

0.6.1 (2010-08-23)

• Added doctest to long_description to render on PyPI.

0.6.0 (2010-08-23)

• Replaced zope.app.container by zope.container.

• Using Python’s doctest module instead of deprecated zope.testing.doctestunit.

0.5.0 (2008-04-12)

• Initial Release