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    <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: &gt;&gt;&gt; shared1 = Shared(1) &gt;&gt;&gt; shared2 = Shared(2) &gt;&gt;&gt; c1 = C(shared1) &gt;&gt;&gt; c2 = C(shared1) &gt;&gt;&gt; c3 = C(shared2) &gt;&gt;&gt; c4 = C(shared2) # c1 and c2 sharing a reference to shared1 &gt;&gt;&gt; c1.x.value 1 &gt;&gt;&gt; c2.x.value 1 # change c2.x will reflect on c1 &gt;&gt;&gt; c2.x.value = 3 &gt;&gt;&gt; c1.x.value 3 # but not on c3, because shared1 and shared2 are distinct namespaces &gt;&gt;&gt; c3.x.value 2 </code></pre> <p>UPDATE:</p> <p>But watch out, it is easy to make a mistake:</p> <pre><code>&gt;&gt;&gt; c4.x = 4 &gt;&gt;&gt; c3.x.value 2 &gt;&gt;&gt; c4.x.value Traceback (most recent call last): File "&lt;interactive input&gt;", line 1, in &lt;module&gt; AttributeError: 'int' object has no attribute 'value' &gt;&gt;&gt; </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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    1. CO@Paulo Scardine: I think this is exactly what I have suggested as a work around. If this is the state of the art I will do it like this. Thank you for confirming that!
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    2. CO@r6d9: see my update, unutbu's answer has an implementation.
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    3. CO@Paulo Scardine: See my comment to unutbu's answer, what do you think?
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