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copied!<p>millimoose gets the green check, but I thought I'd add a bit.</p> <p><strong>tl;dr</strong> </p> <p>Bound method objects are transient. That is, they are created anew each time you grab them.</p> <pre><code>class Foo(object): def bar(object): pass foo = Foo() m1 = foo.bar m2 = foo.bar print (id(m1)) print (id(m2)) # 38121264 # 38952752 </code></pre> <p><strong>More Detail: Descriptor Protocol</strong></p> <p>Bound method objects are created anew each time you grab them because the function object stored on the class implements the <a href="http://docs.python.org/howto/descriptor.html" rel="noreferrer">descriptor protocol</a>.</p> <p>The bar function is stored in the class dict:</p> <pre><code>class Foo(object): def bar(object): pass print (Foo.__dict__['bar']) # <function bar at 0x00000000025F2208> </code></pre> <p>When a Foo instance attempts to access bar, it doesn't have it. So it looks it up on its class and finds it in the class dict. The function object implements a <strong>__get__</strong> method, as per the descriptor protocol. So what is actually called to get the bound method is this:</p> <pre><code>print(Foo.__dict__['bar'].__get__(foo, Foo)) # <bound method Foo.bar of <__main__.Foo object at 0x00000000025719B0>> </code></pre> <p>Which is equivalent to:</p> <pre><code>print (foo.bar) # <bound method Foo.bar of <__main__.Foo object at 0x00000000025719B0>> </code></pre> <p>You can get at the original function like so:</p> <pre><code>print (foo.bar.im_func) # Python 2.x # <function bar at 0x00000000025F2208> print (foo.bar.__func__) # Python 3.x # <function bar at 0x00000000025F2208> </code></pre>

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