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copied!<p>The other answer is right, your question is more about namespaces and references than about inheritance. </p> <p>All variables in Python are references, and all object instance is a namespace. So you can do:</p> <pre><code>class C(): def __init__(self, x): self.x = x class Shared(object): def __init__(self, value): self.value = value # instances: >>> shared1 = Shared(1) >>> shared2 = Shared(2) >>> c1 = C(shared1) >>> c2 = C(shared1) >>> c3 = C(shared2) >>> c4 = C(shared2) # c1 and c2 sharing a reference to shared1 >>> c1.x.value 1 >>> c2.x.value 1 # change c2.x will reflect on c1 >>> c2.x.value = 3 >>> c1.x.value 3 # but not on c3, because shared1 and shared2 are distinct namespaces >>> c3.x.value 2 </code></pre> <p>UPDATE:</p> <p>But watch out, it is easy to make a mistake:</p> <pre><code>>>> c4.x = 4 >>> c3.x.value 2 >>> c4.x.value Traceback (most recent call last): File "<interactive input>", line 1, in <module> AttributeError: 'int' object has no attribute 'value' >>> </code></pre> <p>I think the state of the art would be using <a href="http://docs.python.org/library/functions.html#property" rel="nofollow">properties</a> to hide the <a href="http://docs.python.org/tutorial/classes.html#private-variables" rel="nofollow"><code>__shared_instance</code></a> in a private instance variable - so you can use c1.x instead of c1.x.value and avoid a typo like the example above.</p>

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