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copied!<p>I assume you are using Python 2? In Python 3, <code>C.m is C.m</code> (but <code>C().m is C().m</code> is still false). If you enter just <code>C.m</code> at the REPL, I bet you see something like <code><UnboundMethod... ></code>. An UnboundMethod wrapper does very little, except checking <code>isinstance(self, cls)</code>. (Seems pretty pointless to create a wrapper for this? It is, so it was dropped in Python 3 - <code>C.m</code> is just a function). A fresh wrapper instance is created on-demand whenever the method is accessed - <code>C.m</code> creates one, another <code>C.m</code> creates another one. Since they're different instances, <code>C.m is not C.m</code>.</p> <p>Closely related are the bound methods, which allow you to do <code>f = obj.method; f(*args)</code> but also cause <code>instance.method is not instance.method</code>. Upon instanciation, all functions defined in the class (read: all methods, except of course monkeypatched ones) become properties of the instance. When you access them, you instead get a fresh instance of a wrapper (the bound method) around the plain function. This wrapper remembers the instance (<code>self</code>) and when called with <code>(arg1, arg2, ..., argN)</code> just hands these on to the function - with <code>self</code> added as first argument. You usually don't notice because you call the method right away - but this is what allows passing <code>self</code> implicitly without resorting to language-level trickery.</p> <p>See <a href="http://python-history.blogspot.com/2009/02/first-class-everything.html" rel="nofollow">the history of Python</a> for more details and, well, history.</p>

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