Source Code for Module glitter.utils.proxy

  1  """Base classes for descriptors and descriptor owners. 
  2   
  3  @bug: L{Proxy} is currently unaware of its context. 
  4  @author: Stephan Wenger 
  5  @date: 2012-02-29 
  6  """ 
  7   
  8  from inspect import getmembers as _getmembers 
  9  import types as _types 
 10  import numpy as _np 
 11   
 12  import glitter.raw as _gl 
 13  from glitter.utils.dtypes import coerce_array, int32 
 14  from glitter.utils.objects import with_obj 
 15   
 16 -class Proxy(object): 
 17 -    def __init__(self, getter=None, get_args=(), setter=None, set_args=(), dtype=None, shape=(), enum=None, name=None): 
 18          self._getter = getter 
 19          self._get_args = get_args 
 20          self._setter = setter 
 21          self._set_args = set_args 
 22          self._dtype = dtype if dtype else int32 
 23          self._shape = None if shape is None else tuple(shape) if hasattr(shape, "__iter__") else (shape,) 
 24          self._enum = enum 
 25          self._name = name 
 26   
 27 -    def __get__(self, obj, cls): 
 28          _value = _np.empty(self._shape, dtype=self._dtype.as_numpy()) 
 29          args = list(self._get_args) + [_gl.cast(_value.ctypes, self._getter.argtypes[-1])] 
 30          with obj: 
 31              self._getter(*args) 
 32          value = _value.item() if _value.shape is () else _value 
 33          if self._enum is not None: 
 34              if hasattr(value, "__iter__"): 
 35                  value = [self._enum[x] for x in value] 
 36              else: 
 37                  value = self._enum[value] 
 38          return value 
 39   
 40 -    def __set__(self, obj, value): 
 41          if self._setter is None: 
 42              raise AttributeError("can't set attribute") 
 43          if self._enum is not None: 
 44              if hasattr(value, "__iter__"): 
 45                  _value = [self._enum(x)._value for x in value] 
 46              else: 
 47                  _value = self._enum(value)._value 
 48          else: 
 49              _value = value 
 50          _value = coerce_array(_value, dtype=self._dtype) 
 51          if len(self._set_args) + len(_value) == len(self._setter.argtypes): 
 52              args = list(self._set_args) + (list(_value) if _value.ndim == 1 else [x.ctypes for x in _value]) 
 53          elif len(self._set_args) + 1 == len(self._setter.argtypes): 
 54              args = list(self._set_args) + [_value.ctypes] 
 55          else: 
 56              raise RuntimeError("no valid setter invocation found") 
 57          with obj: 
 58              self._setter(*args) 
 59   
 60 -    def __repr__(self): 
 61          if self._name: 
 62              return "proxy for %s" % self._name 
 63          elif self._getter and self._setter: 
 64              return "proxy for %s(%s) / %s(%s)" % ( 
 65                      self._getter.__name__, ", ".join(map(str, self._get_args)), 
 66                      self._setter.__name__, ", ".join(map(str, self._set_args))) 
 67          elif self._getter: 
 68              return "proxy for %s(%s)" % (self._getter.__name__, ", ".join(map(str, self._get_args))) 
 69          elif self._setter: 
 70              return "proxy for %s(%s)" % (self._setter.__name__, ", ".join(map(str, self._set_args))) 
 71          else: 
 72              return "proxy object" 
 73   
 74 -class ListProxy(object): 
 75 -    def __init__(self, lst, insert_callback=None, delete_callback=None): 
 76          self._lst = lst 
 77          self._insert_callback = insert_callback 
 78          self._delete_callback = delete_callback 
 79   
 80 -    def append(self, x): 
 81          self._lst.append(x) 
 82          self._insert_callback(x) 
 83   
 84 -    def extend(self, xs): 
 85          for x in xs: 
 86              self.append(x) 
 87   
 88 -    def remove(self, x): 
 89          self._lst.remove(x) 
 90          self._delete_callback(x) 
 91   
 92 -    def __iadd__(self, xs): 
 93          self.extend(xs) 
 94   
 95 -    def __getitem__(self, key): 
 96          return self._lst[key] 
 97   
 98 -    def __len__(self): 
 99          return len(self._lst) 
100   
101 -class InstanceDescriptorMixin(object): 
102      """Mixin to enable runtime-added descriptors.""" 
103   
104 -    def __getattribute__(self, name): 
105          attr = super(InstanceDescriptorMixin, self).__getattribute__(name) 
106          if hasattr(attr, "__get__") and not callable(attr): 
107              return attr.__get__(self, self.__class__) 
108          else: 
109              return attr 
110   
111 -    def __setattr__(self, name, value): 
112          try: 
113              attr = super(InstanceDescriptorMixin, self).__getattribute__(name) 
114              return attr.__set__(self, value) 
115          except AttributeError: 
116              return super(InstanceDescriptorMixin, self).__setattr__(name, value) 
117   
118 -class PropertyProxy(object): 
119 -    def __init__(self, obj, name): 
120          self._obj = obj 
121          self._name = name 
122   
123 -    def __get__(self, obj, cls): 
124          return getattr(self._obj, self._name) 
125   
126 -    def __set__(self, obj, value): 
127          setattr(self._obj, self._name, value) 
128   
129 -    def __delete__(self, obj): 
130          delattr(self._obj, self._name) 
131   
132 -class ItemProxy(object): 
133 -    def __init__(self, obj, idx): 
134          self._obj = obj 
135          self._idx = idx 
136   
137 -    def __get__(self, obj, cls): 
138          return self._obj[self._idx] 
139   
140 -    def __set__(self, obj, value): 
141          self._obj[self._idx] = value 
142   
143 -    def __delete__(self, obj): 
144          del self._obj[self._idx] 
145   
146 -def add_proxies(parent, obj): 
147      """Add proxies for methods and properties of C{obj} to C{parent}.""" 
148   
149      # add functions and methods 
150      for key, value in _getmembers(obj): 
151          if key.startswith("_"): 
152              continue 
153          if isinstance(value, (_types.FunctionType, _types.MethodType)): 
154              setattr(parent, key, with_obj(parent, value)) 
155   
156      # add properties and other descriptors (can be accessed via the class only) 
157      for key, value in _getmembers(type(obj)): 
158          if key.startswith("_"): 
159              continue 
160          if hasattr(value, "__get__") and not callable(value): # exclude member functions 
161              setattr(parent, key, PropertyProxy(obj, key)) 
162   
163      # add instance descriptors if applicable 
164      if isinstance(obj, InstanceDescriptorMixin): 
165          for key, value in obj.__dict__.items(): 
166              if key.startswith("_"): 
167                  continue 
168              if hasattr(value, "__get__"): 
169                  setattr(parent, key, PropertyProxy(obj, key)) 
170           
171  __all__ = ["Proxy", "ListProxy", "InstanceDescriptorMixin", "PropertyProxy", "ItemProxy", "add_proxies"] 
172