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    <p>The <a href="http://docs.python.org/library/functions.html#property"><code>property</code> decorator</a> only works with <em>new-style</em> classes; that is to say, classes that inherit from <code>object</code>. Acquisition (which gives you access to the global <code>REQUEST</code> object via attribute access) on the other hand is very much 'old-skool' python and the two do not work well together, as <code>property</code> <em>ignores</em> acquisition wrappers, which are needed to acquire the <code>REQUEST</code> object.</p> <p>Zope has it's own <code>property</code>-like method that pre-dates new-style classes and the <code>property</code> decorater, called <a href="http://wiki.zope.org/zope2/ComputedAttribute"><code>ComputedAttribute</code></a>, which actually predates the <code>property</code> decorator and new-style classes by many years. A <code>ComputedAttribute</code>-wrapped function does know how to behave with an <code>Acquisition</code>-wrapped object, though.</p> <p>You can use <code>ComputedAttibute</code> much like the <code>property</code> decorator:</p> <pre><code>from ComputedAttribute import ComputedAttribute class SomeClass(): @ComputedAttribute def someProperty(self): return 'somevalue' </code></pre> <p>The <code>ComputedAttribute</code> wrapper function also can be configured with a level of wrapping, which is what we need when dealing with Acquisition wrappers. You cannot use the <code>ComputedAttribute</code> as a decorator in that case:</p> <pre><code>class SomeClass(): def someValue(self): return self.REQUEST someValue = ComputedAttribute(someValue, 1) </code></pre> <p>It is easy enough to define a new function to do the decorating for us though:</p> <pre><code>from ComputedAttribute import ComputedAttribute def computed_attribute_decorator(level=0): def computed_attribute_wrapper(func): return ComputedAttribute(func, level) return computed_attribute_wrapper </code></pre> <p>Stick this in a utility module somewhere, after which you can then use it as a callable decorator to mark something as an Acquisition-aware property:</p> <pre><code>class SomeClass(): @computed_attribute_decorator(level=1) def someValue(self): return self.REQUEST </code></pre> <p>Note that unlike <code>property</code>, <code>ComputedAttribute</code> can only be used for getters; there is no support for setters or deleters.</p>
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    1. POZope: cannot access REQUEST under property decorator
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    1. USMartijn Pieters
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    1. COThank you so much! I'm using Zope for a couple of years already and never stumbled over the ComputedAttribute method.
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