Lib/copy_reg.py

   1 """Helper to provide extensibility for pickle/cPickle.
   2
   3 This is only useful to add pickle support for extension types defined in
   4 C, not for instances of user-defined classes.
   5 """
   6
   7 from types import ClassType as _ClassType
   8
   9 __all__ = ["pickle","constructor"]
  10
  11 dispatch_table = {}
  12 safe_constructors = {}
  13
  14 def pickle(ob_type, pickle_function, constructor_ob=None):
  15     if type(ob_type) is _ClassType:
  16         raise TypeError("copy_reg is not intended for use with classes")
  17
  18     if not callable(pickle_function):
  19         raise TypeError("reduction functions must be callable")
  20     dispatch_table[ob_type] = pickle_function
  21
  22     if constructor_ob is not None:
  23         constructor(constructor_ob)
  24
  25 def constructor(object):
  26     if not callable(object):
  27         raise TypeError("constructors must be callable")
  28     safe_constructors[object] = 1
  29
  30 # Example: provide pickling support for complex numbers.
  31
  32 def pickle_complex(c):
  33     return complex, (c.real, c.imag)
  34
  35 pickle(type(1j), pickle_complex, complex)
  36
  37 # Support for picking new-style objects
  38
  39 def _reconstructor(cls, base, state):
  40     obj = base.__new__(cls, state)
  41     base.__init__(obj, state)
  42     return obj
  43 _reconstructor.__safe_for_unpickling__ = 1
  44
  45 _HEAPTYPE = 1<<9
  46
  47 def _reduce(self):
  48     for base in self.__class__.__mro__:
  49         if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE:
  50             break
  51     else:
  52         base = object # not really reachable
  53     if base is object:
  54         state = None
  55     else:
  56         state = base(self)
  57     args = (self.__class__, base, state)
  58     try:
  59         getstate = self.__getstate__
  60     except AttributeError:
  61         try:
  62             dict = self.__dict__
  63         except AttributeError:
  64             dict = None
  65     else:
  66         dict = getstate()
  67     if dict:
  68         return _reconstructor, args, dict
  69     else:
  70         return _reconstructor, args