forum/modules/decorators.py

   1 import inspect
   2
   3 class DecoratableObject(object):
   4     MODE_OVERRIDE = 0
   5     MODE_PARAMS = 1
   6     MODE_RESULT = 2
   7
   8     def __init__(self, fn, is_method=False):
   9         self._callable = fn
  10         self.is_method = is_method
  11
  12         self._params_decoration = None
  13         self._result_decoration = None
  14
  15     def _decorate(self, fn, mode, **kwargs):
  16         if mode == self.MODE_OVERRIDE:
  17             self._decorate_full(fn, **kwargs)
  18         elif mode == self.MODE_PARAMS:
  19             self._decorate_params(fn)
  20         elif mode == self.MODE_RESULT:
  21             self._decorate_result(fn, **kwargs)
  22
  23     def _decorate_full(self, fn, needs_origin=True):
  24         origin = self._callable
  25
  26         if needs_origin:
  27             if self.is_method:
  28                 self._callable = lambda inst, *args, **kwargs: fn(inst, origin, *args, **kwargs)
  29             else:
  30                 self._callable = lambda *args, **kwargs: fn(origin, *args, **kwargs)
  31         else:
  32             self._callable = fn
  33
  34     def _decorate_params(self, fn):
  35         if not self._params_decoration:
  36             self._params_decoration = []
  37
  38         self._params_decoration.append(fn)
  39
  40     def _decorate_result(self, fn, needs_params=False):
  41         if not self._result_decoration:
  42             self._result_decoration = []
  43
  44         fn._needs_params = needs_params
  45         self._result_decoration.append(fn)
  46
  47     def __call__(self, *args, **kwargs):
  48         if self._params_decoration:
  49             for dec in self._params_decoration:
  50                 try:
  51                     args, kwargs = dec(*args, **kwargs)
  52                 except ReturnImediatelyException, e:
  53                     return e.ret
  54
  55         res = self._callable(*args, **kwargs)
  56
  57         if self._result_decoration:
  58             for dec in self._result_decoration:
  59                 if dec._needs_params:
  60                     res = dec(res, *args, **kwargs)
  61                 else:
  62                     res = dec(res)
  63
  64         return res
  65
  66 class ReturnImediatelyException(Exception):
  67     def __init__(self, ret):
  68         super(Exception, self).__init__()
  69         self.ret = ret
  70
  71 def _check_decoratable(origin, install=True):
  72     if not hasattr(origin, '_decoratable_obj'):
  73         if inspect.ismethod(origin) and not hasattr(origin, '_decoratable_obj'):
  74             decoratable = DecoratableObject(origin)
  75
  76             def decoratable_method(self, *args, **kwargs):
  77                 return decoratable(self, *args, **kwargs)
  78
  79             decoratable_method._decoratable_obj = decoratable
  80
  81             def decoratable_decorate(fn, mode, **kwargs):
  82                 decoratable._decorate(fn, mode, **kwargs)
  83
  84             decoratable_method._decorate = decoratable_decorate
  85
  86             if install:
  87                 setattr(origin.im_class, origin.__name__, decoratable_method)
  88
  89             return decoratable_method
  90
  91         elif inspect.isfunction(origin):
  92             decoratable = DecoratableObject(origin)
  93
  94             def decorated(*args, **kwargs):
  95                 return decoratable(*args, **kwargs)
  96
  97             decorated._decoratable_obj = decoratable
  98
  99             if install:
 100                 setattr(inspect.getmodule(origin), origin.__name__, decorated)
 101
 102             decorated.__name__ = origin.__name__
 103             decorated.__module__ = origin.__module__
 104
 105             return decorated
 106
 107     return origin
 108
 109
 110 def decorate(origin, needs_origin=True):
 111     origin = _check_decoratable(origin)
 112
 113     def decorator(fn):
 114         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_OVERRIDE, needs_origin=needs_origin)
 115
 116     return decorator
 117
 118
 119 def _decorate_params(origin):
 120     origin = _check_decoratable(origin)
 121
 122     def decorator(fn):
 123         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_PARAMS)
 124
 125     return decorator
 126
 127 decorate.params = _decorate_params
 128
 129 def _decorate_result(origin, needs_params=False):
 130     origin = _check_decoratable(origin)
 131
 132     def decorator(fn):
 133         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_RESULT, needs_params=needs_params)
 134
 135     return decorator
 136
 137 decorate.result = _decorate_result
 138
 139 def _decorate_with(fn):
 140     def decorator(origin):
 141         origin = _check_decoratable(origin)
 142         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_OVERRIDE, needs_origin=True)
 143         return origin
 144     return decorator
 145
 146 decorate.withfn = _decorate_with
 147
 148 def _decorate_result_with(fn, needs_params=False):
 149     def decorator(origin):
 150         origin = _check_decoratable(origin)
 151         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_RESULT, needs_params=needs_params)
 152         return origin
 153     return decorator
 154
 155 decorate.result.withfn = _decorate_result_with
 156
 157 def _decorate_params_with(fn):
 158     def decorator(origin):
 159         origin = _check_decoratable(origin)
 160         origin._decoratable_obj._decorate(fn, DecoratableObject.MODE_PARAMS)
 161         return origin
 162     return decorator
 163
 164 decorate.params.withfn = _decorate_params_with