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copied!<p>I found the answer the the problem. It has to do with the renaming of attributes in class-private variables. This can be seen for <a href="http://docs.python.org/3.0/tutorial/classes.html#private-variables" rel="nofollow">python 3 here</a> under Private Variables and for <a href="http://docs.python.org/2/tutorial/classes.html#private-variables-and-class-local-references" rel="nofollow">python 2 here</a> section 9.6 Private Variables and Class-local References.</p> <p>In the code with the function as a method (the second listing above), the <code>f.__case</code> was renamed to <code>f._switch__case</code>. If every instance of <code>__case</code> is replaced with <code>_switch__case</code> except for the <code>@staticmethod</code> function, the code works as it should. I'm not 100% sure why Python is designed this way, but I'm guessing it has something to do with preserving namespace, but I'm not sure why it is necessary as <code>class</code> has its own namespace.</p> <p>Below is the corrected code:</p> <pre><code>class switch: def __init__(self): self.__case_map = {} def set_case(key,f): self.__case_map[key] = f a = [getattr(self,e) for e in dir(self) if getattr(self,e) is not None and hasattr(getattr(self,e),'_switch__case')] for f in a: cases = getattr(f,'_switch__case') if isinstance(cases,tuple) or isinstance(cases,list): for c in cases: set_case(c,f) else: set_case(cases,f) def match(self,value): try: self.__case_map[value] except KeyError: return self.__case_map['_default'] return self.__case_map[value] @staticmethod def case(comparision): def __assign_case(f): f.__case = comparision return f return __assign_case class b(switch): @switch.case((1,3)) def event_one(self): print('Event handler for 1,3 in b') @switch.case(2) def event_two(self): print('Event handler for 2 in b') @switch.case('_default') def default(self): print('No match was found, using default case') a = b() a.match(1)() a.match(2)() a.match(5)() </code></pre>

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