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copied!<p>As per my comment on @Mark's answer, I like the factory approach he's advocating. However, I wouldn't do it exactly his way, because he makes a new class afresh every time. Rather, this is a nice use case for mixin MI and <code>super</code>, as follows:</p> <pre><code>class MyConnectionPlugin(object): def __init__(self, *args, **kw): super(MyConnectionPlugin, self).__init__(*args, **kw) # etc etc -- rest of initiatizations, other methods class SecureConnection(MyConnectionPlugin, httplib.HTTPSConnection, object): pass class PlainConnection(MyConnectionPlugin, httplib.HTTPConnection, object): pass def ConnectionClass(secure): if secure: return SecureConnection else: return PlainConnection conn = ConnectionClass(whatever_expression())() </code></pre> <p>etc.</p> <p>Now, alternatives ARE possible, since a Python object can change its own <code>__class__</code>, and so forth. However, like shooting flies with a rhino rifle, using excessive force (extremely powerful, deep, and near-magical language features) to solve problems that can be nicely solved with reasonable restraint (the equivalent of a flyswatter), is NOT recommended;-).</p> <p><strong>Edit</strong>: the extra injection of <code>object</code> in the bases is needed only to compensate for the sad fact that in Python 2.* the HTTPConnection class is old-style and therefore doesn't play well with others -- witness...:</p> <pre><code>>>> import httplib >>> class Z(object): pass ... >>> class Y(Z, httplib.HTTPConnection): pass ... >>> Y.mro() [<class '__main__.Y'>, <class '__main__.Z'>, <type 'object'>, <class httplib.HTTPConnection at 0x264ae0>] >>> class X(Z, httplib.HTTPConnection, object): pass ... >>> X.mro() [<class '__main__.X'>, <class '__main__.Z'>, <class httplib.HTTPConnection at 0x264ae0>, <type 'object'>] >>> </code></pre> <p>The method-resolution order (aka MRO) in class Y (without the further injection of an <code>object</code> base) has object before the class from httplib (so <code>super</code> doesn't do the right thing), but the extra injection jiggles the MRO to compensate. Alas, such care is needed in Python 2.* when dealing with bad old legacy-style classes; fortunately, in Python 3, the legacy style has disappeared and every class "plays well with others" as it should!-)</p>

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