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copied!<p>In Python 2, <em>type</em> and <em>class</em> are not the same thing, specifically, for old-style classes, <code>type(obj)</code> <a href="https://stackoverflow.com/questions/1549801/differences-between-isinstance-and-type-in-python">is not the same object</a> as <code>obj.__class__</code>. So it is possible because instances of old-style classes are actually of a different type (<code>instance</code>) than their class:</p> <pre><code>>>> class A(): pass >>> class B(A): pass >>> b = B() >>> assert b.__class__ is B >>> issubclass(b.__class__, A) # same as issubclass(B, A) True >>> issubclass(type(b), A) False >>> type(b) <type 'instance'> >>> b.__class__ <class __main__.B at 0x10043aa10> </code></pre> <p>This is resolved in new-style classes: </p> <pre><code>>>> class NA(object): pass >>> class NB(NA): pass >>> nb = NB() >>> issubclass(type(nb), NA) True >>> type(nb) <class '__main__.NB'> >>> nb.__class__ <class '__main__.NB'> </code></pre> <p>Old-style class is not a type, new-style class is:</p> <pre><code>>>> isinstance(A, type) False >>> isinstance(NA, type) True </code></pre> <p>Old style classes are declared deprecated. In Python 3, there are only new-style classes; <code>class A()</code> is equivalent to <code>class A(object)</code> and your code will yield <code>True</code> in both checks.</p> <p>Take a look at this question for some more discussion: <a href="https://stackoverflow.com/questions/54867/old-style-and-new-style-classes-in-python">What is the difference between old style and new style classes in Python?</a></p>

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