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annotate pyikriam/utils.py @ 363:3b2658751efa

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author "Rex Tsai <chihchun@kalug.linux.org.tw>"
date Sun, 01 Mar 2009 11:09:44 +0800
parents 7551342718b6
children
rev   line source
160
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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1 ## \brief decorator is a class decorate another of another object.
7551342718b6 Refactory pyikriam with patterns.
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2 #
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3 # Access of attributes/methods that can not be found in an instance
7551342718b6 Refactory pyikriam with patterns.
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4 # of a class of this meta-class, decorator, are delegated to the backend
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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5 # of the instance.
7551342718b6 Refactory pyikriam with patterns.
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6 #
7551342718b6 Refactory pyikriam with patterns.
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7 # A backend object always passed as first parameter when
7551342718b6 Refactory pyikriam with patterns.
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8 # instantiate an instance of a class with decorator as meta-class.
7551342718b6 Refactory pyikriam with patterns.
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9 # For example,
7551342718b6 Refactory pyikriam with patterns.
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10 # \code
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11 # class foo(object):
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12 # __metaclass__ = decorator
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13 #
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14 # backend.data = 3
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15 # obj = foo(backend)
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16 # print obj.data
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17 # backend.data = 4
7551342718b6 Refactory pyikriam with patterns.
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18 # print obj.data
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19 # \endcode
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20 # it print out 3 and 4 respectively.
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21 #
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22 class decorator(type):
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23 def __init__(clz, name, base, dict):
7551342718b6 Refactory pyikriam with patterns.
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24 super(decorator, clz).__init__(name, base, dict)
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25 clz.__getattr__ = decorator.__dele_getattr
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26 pass
7551342718b6 Refactory pyikriam with patterns.
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27
7551342718b6 Refactory pyikriam with patterns.
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28 @staticmethod
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29 def set_backend(obj, backend):
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30 obj.__backend = backend
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31 pass
7551342718b6 Refactory pyikriam with patterns.
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32
7551342718b6 Refactory pyikriam with patterns.
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33 @staticmethod
7551342718b6 Refactory pyikriam with patterns.
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34 def __dele_getattr(obj, name):
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35 return getattr(obj.__backend, name)
7551342718b6 Refactory pyikriam with patterns.
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36 pass
7551342718b6 Refactory pyikriam with patterns.
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37
7551342718b6 Refactory pyikriam with patterns.
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38
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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39 ## \brief Decorator to make functions or methods dynamic programming.
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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40 #
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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41 # dyna_prog result of functions or methods with their arguments as key.
7551342718b6 Refactory pyikriam with patterns.
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42 # It supposes result of a function always the same if the same arguments
7551342718b6 Refactory pyikriam with patterns.
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43 # are passed. It cache result of cached function to avoid really calling
7551342718b6 Refactory pyikriam with patterns.
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44 # function every time.
7551342718b6 Refactory pyikriam with patterns.
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45 class dyna_prog(object):
7551342718b6 Refactory pyikriam with patterns.
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46 class functor(object):
7551342718b6 Refactory pyikriam with patterns.
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47 def __init__(self, instance, method):
7551342718b6 Refactory pyikriam with patterns.
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48 self._method = method
7551342718b6 Refactory pyikriam with patterns.
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49 self._instance = instance
7551342718b6 Refactory pyikriam with patterns.
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50 self._cache = {}
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51 pass
7551342718b6 Refactory pyikriam with patterns.
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52
7551342718b6 Refactory pyikriam with patterns.
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53 def __call__(self, *args):
7551342718b6 Refactory pyikriam with patterns.
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54 try:
7551342718b6 Refactory pyikriam with patterns.
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55 return self._cache[args]
7551342718b6 Refactory pyikriam with patterns.
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56 except KeyError:
7551342718b6 Refactory pyikriam with patterns.
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57 pass
7551342718b6 Refactory pyikriam with patterns.
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58 instance = self._instance
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59 result = self._method(instance, *args)
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60 return self._cache.setdefault(args, result)
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61
7551342718b6 Refactory pyikriam with patterns.
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62 def clear(self):
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63 self._cache.clear()
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64 pass
7551342718b6 Refactory pyikriam with patterns.
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65
7551342718b6 Refactory pyikriam with patterns.
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66 def __init__(self, method):
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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67 super(dyna_prog, self).__init__()
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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68 self._method = method
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69 self._functors = {}
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70 pass
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71
7551342718b6 Refactory pyikriam with patterns.
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72 def __get__(self, instance, owner):
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73 try:
7551342718b6 Refactory pyikriam with patterns.
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74 return self._functors[instance]
7551342718b6 Refactory pyikriam with patterns.
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75 except KeyError:
7551342718b6 Refactory pyikriam with patterns.
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76 pass
7551342718b6 Refactory pyikriam with patterns.
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77 functor_o = dyna_prog.functor(instance, self._method)
7551342718b6 Refactory pyikriam with patterns.
Thinker K.F. Li <thinker@branda.to>
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78 return self._functors.setdefault(instance, functor_o)
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79 pass
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80