zc.freeze 1.2

便利性

该包确实提供了两个 IFreezing 的默认实现和一些便利功能。

一个 IFreezing 实现是为直接了解此 API 的对象设计的（与从适配器和其它组件组装的功能相反）。

>>> import zc.freeze
>>> v = zc.freeze.Freezing()
>>> from zc.freeze import interfaces
>>> from zope.interface.verify import verifyObject
>>> verifyObject(interfaces.IFreezing, v)
True
>>> verifyObject(interfaces.IFreezable, v)
True
>>> v._z_frozen
False
>>> v._z_frozen = True
Traceback (most recent call last):
...
AttributeError: can't set attribute
>>> import pytz
>>> import datetime
>>> before = datetime.datetime.now(pytz.utc)
>>> v._z_freeze()
>>> before <= v._z_freeze_timestamp <= datetime.datetime.now(pytz.utc)
True
>>> v._z_frozen
True
>>> interfaces.IObjectFrozenEvent.providedBy(events[-1])
True
>>> events[-1].object is v
True
>>> v._z_freeze()
Traceback (most recent call last):
...
FrozenError

另一个可用的实现是适配器，并将信息存储在注解中。这里有一个快速演示。

>>> import zope.annotation.interfaces
>>> from zope import interface, component
>>> class Demo(object):
...     interface.implements(zope.annotation.interfaces.IAnnotatable)
...
>>> import UserDict
>>> class DemoAnnotations(UserDict.UserDict):
...     interface.implements(zope.annotation.interfaces.IAnnotations)
...     component.adapts(Demo)
...     def __init__(self, context):
...         self.context = context
...         self.data = getattr(context, '_z_demo', None)
...         if self.data is None:
...             self.data = context._z_demo = {}
...
>>> component.provideAdapter(DemoAnnotations)
>>> component.provideAdapter(zc.freeze.FreezingAdapter)
>>> d = Demo()
>>> verifyObject(interfaces.IFreezing, interfaces.IFreezing(d))
True
>>> verifyObject(interfaces.IFreezable, interfaces.IFreezing(d))
True
>>> interfaces.IFreezing(d)._z_frozen
False
>>> interfaces.IFreezing(d)._z_frozen = True
Traceback (most recent call last):
...
AttributeError: can't set attribute
>>> before = datetime.datetime.now(pytz.utc)
>>> interfaces.IFreezing(d)._z_freeze()
>>> (before <= interfaces.IFreezing(d)._z_freeze_timestamp <=
...  datetime.datetime.now(pytz.utc))
True
>>> interfaces.IFreezing(d)._z_frozen
True
>>> interfaces.IObjectFrozenEvent.providedBy(events[-1])
True
>>> events[-1].object is d
True
>>> interfaces.IFreezing(d)._z_freeze()
Traceback (most recent call last):
...
FrozenError

zc.freeze 模块还包含三个用于编写具有冻结感知属性的辅助函数。

一个“方法”函数可以生成一个具有冻结感知的方法，如果对象已冻结，将引发 FrozenError。

“setproperty”和“delproperty”函数可以生成一个具有冻结感知的描述符，如果在冻结对象上调用 set 或 del 方法，将引发 FrozenError。这些都是可读写属性。

“makeProperty”生成一个具有冻结感知的描述符，执行简单的 get/set 操作，但在尝试在冻结对象上设置时引发 FrozenError。

>>> class BiggerDemo(Demo):
...     counter = 0
...     @zc.freeze.method
...     def increase(self):
...         self.counter += 1
...     _complex = 1
...     @property
...     def complex_property(self):
...         return str(self._complex)
...     @zc.freeze.setproperty
...     def complex_property(self, value):
...         self._complex = value * 2
...     zc.freeze.makeProperty('simple_property')
...
>>> d = BiggerDemo()
>>> d.counter
0
>>> d.complex_property
'1'
>>> d.simple_property # None
>>> d.increase()
>>> d.counter
1
>>> d.complex_property = 4
>>> d.complex_property
'8'
>>> d.simple_property = 'hi'
>>> d.simple_property
'hi'
>>> interfaces.IFreezing(d)._z_frozen
False
>>> interfaces.IFreezing(d)._z_freeze()
>>> interfaces.IFreezing(d)._z_frozen
True
>>> d.counter
1
>>> d.increase()
Traceback (most recent call last):
...
FrozenError
>>> d.counter
1
>>> d.complex_property
'8'
>>> d.complex_property = 10
Traceback (most recent call last):
...
FrozenError
>>> d.complex_property
'8'
>>> d.simple_property
'hi'
>>> d.simple_property = 'bye'
Traceback (most recent call last):
...
FrozenError
>>> d.simple_property
'hi'

1.2 (2011-04-08)

• 更新测试以与 ZTK 1.0 一起运行。

• 使用 Python 的 doctest 模块而不是已弃用的 zope.testing.doctest。

• 依赖于 zope.locking 的较新版本。

1.1

（支持 Zope 3.4/eggs）

1.0

（支持 Zope 3.3/no eggs）