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copied!<ol> <li><p>I don't see why you should generally avoid to derive from built-in types. It was considered an improvement that the arrival of new-style classes enabled to do this, and even before this the standard library provided the <code>UserDict</code> and <code>UserList</code> classes to derive from. Of course you have to evaluate in every specific case whether inheritance or composition is what you need, but that's how in always is in OOP -- nothing special about built-in types here.</p></li> <li><p>I wouldn't recommend <code>super()</code> in the example. It is only useful if all cooperating methods have the same signature, or at least cooperating signatures. For single inheritance and "diamond-free" multiple inheritance, explicitly calling base-class methods is fine in my opinion. If you want to get things right in multiple inheritance with diamonds, you are forced to use <code>super()</code>, but you have to design your methods carefully, see <a href="http://rhettinger.wordpress.com/2011/05/26/super-considered-super/" rel="nofollow">Raymond Hettinger's "Python's <code>super()</code> considered super!"</a></p> <p>It is generally safe to use <code>super()</code> in cases where all involved methods have exactly the same signature, including methods likes <code>__getattr__()</code> and <code>__setattr__()</code>.</p></li> <li><p>Your example class is a rather questionable implementation of an <code>Enum</code> type, but not for any of the reasons you mentioned in your post. It mixes up two namespaces: The namespace of the attributes of <code>dict</code> and the enumeration entries. Try <code>Enum("clear", "update")</code> to see what I mean. In this particular case, the follwing implementation would be much better:</p> <pre><code>class Enum(object): def __init__(self, *values): vars(self).update({mnemo: num for num, mnemo in enumerate(values)}) </code></pre> <p>This adds the enumeration entries as attributes to a standard instance without deriving from <code>dict</code>. Every custom class instance brings its own dictionary anyway, namely <code>__dict__</code>.</p></li> </ol>

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