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copied!<p><strong>Method replacement for object instance</strong></p> <p>You can replace methods of already created object instances. It allows you to create object instance with different (exceptional) functionality:</p> <pre><code>>>> class C(object): ... def fun(self): ... print "C.a", self ... >>> inst = C() >>> inst.fun() # C.a method is executed C.a <__main__.C object at 0x00AE74D0> >>> instancemethod = type(C.fun) >>> >>> def fun2(self): ... print "fun2", self ... >>> inst.fun = instancemethod(fun2, inst, C) # Now we are replace C.a by fun2 >>> inst.fun() # ... and fun2 is executed fun2 <__main__.C object at 0x00AE74D0> </code></pre> <p>As we can <code>C.a</code> was replaced by <code>fun2()</code> in <code>inst</code> instance (<code>self</code> didn't change).</p> <p>Alternatively we may use <code>new</code> module, but it's depreciated since Python 2.6:</p> <pre><code>>>> def fun3(self): ... print "fun3", self ... >>> import new >>> inst.fun = new.instancemethod(fun3, inst, C) >>> inst.fun() fun3 <__main__.C object at 0x00AE74D0> </code></pre> <p><strong>Node:</strong> This solution shouldn't be used as general replacement of inheritance mechanism! But it may be very handy in some specific situations (debugging, mocking).</p> <p><strong>Warning:</strong> This solution will not work for built-in types and for new style classes using slots.</p>

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