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authorGeorg Brandl <georg@python.org>2008-05-20 07:49:57 (GMT)
committerGeorg Brandl <georg@python.org>2008-05-20 07:49:57 (GMT)
commitdffbf5f5421cbeb20237280c0bd70f989269f844 (patch)
tree51a520dcf10d589bd145d9117b010dab6bc28e3b /Lib/copy_reg.py
parent06d2a2cb0e105019e8bd5e29a3c81c6874e6396a (diff)
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Revert copy_reg -> copyreg rename.
Diffstat (limited to 'Lib/copy_reg.py')
-rw-r--r--Lib/copy_reg.py201
1 files changed, 201 insertions, 0 deletions
diff --git a/Lib/copy_reg.py b/Lib/copy_reg.py
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index 0000000..db17150
--- /dev/null
+++ b/Lib/copy_reg.py
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+"""Helper to provide extensibility for pickle/cPickle.
+
+This is only useful to add pickle support for extension types defined in
+C, not for instances of user-defined classes.
+"""
+
+from types import ClassType as _ClassType
+
+__all__ = ["pickle", "constructor",
+ "add_extension", "remove_extension", "clear_extension_cache"]
+
+dispatch_table = {}
+
+def pickle(ob_type, pickle_function, constructor_ob=None):
+ if type(ob_type) is _ClassType:
+ raise TypeError("copy_reg is not intended for use with classes")
+
+ if not hasattr(pickle_function, '__call__'):
+ raise TypeError("reduction functions must be callable")
+ dispatch_table[ob_type] = pickle_function
+
+ # The constructor_ob function is a vestige of safe for unpickling.
+ # There is no reason for the caller to pass it anymore.
+ if constructor_ob is not None:
+ constructor(constructor_ob)
+
+def constructor(object):
+ if not hasattr(object, '__call__'):
+ raise TypeError("constructors must be callable")
+
+# Example: provide pickling support for complex numbers.
+
+try:
+ complex
+except NameError:
+ pass
+else:
+
+ def pickle_complex(c):
+ return complex, (c.real, c.imag)
+
+ pickle(complex, pickle_complex, complex)
+
+# Support for pickling new-style objects
+
+def _reconstructor(cls, base, state):
+ if base is object:
+ obj = object.__new__(cls)
+ else:
+ obj = base.__new__(cls, state)
+ if base.__init__ != object.__init__:
+ base.__init__(obj, state)
+ return obj
+
+_HEAPTYPE = 1<<9
+
+# Python code for object.__reduce_ex__ for protocols 0 and 1
+
+def _reduce_ex(self, proto):
+ assert proto < 2
+ for base in self.__class__.__mro__:
+ if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE:
+ break
+ else:
+ base = object # not really reachable
+ if base is object:
+ state = None
+ else:
+ if base is self.__class__:
+ raise TypeError, "can't pickle %s objects" % base.__name__
+ state = base(self)
+ args = (self.__class__, base, state)
+ try:
+ getstate = self.__getstate__
+ except AttributeError:
+ if getattr(self, "__slots__", None):
+ raise TypeError("a class that defines __slots__ without "
+ "defining __getstate__ cannot be pickled")
+ try:
+ dict = self.__dict__
+ except AttributeError:
+ dict = None
+ else:
+ dict = getstate()
+ if dict:
+ return _reconstructor, args, dict
+ else:
+ return _reconstructor, args
+
+# Helper for __reduce_ex__ protocol 2
+
+def __newobj__(cls, *args):
+ return cls.__new__(cls, *args)
+
+def _slotnames(cls):
+ """Return a list of slot names for a given class.
+
+ This needs to find slots defined by the class and its bases, so we
+ can't simply return the __slots__ attribute. We must walk down
+ the Method Resolution Order and concatenate the __slots__ of each
+ class found there. (This assumes classes don't modify their
+ __slots__ attribute to misrepresent their slots after the class is
+ defined.)
+ """
+
+ # Get the value from a cache in the class if possible
+ names = cls.__dict__.get("__slotnames__")
+ if names is not None:
+ return names
+
+ # Not cached -- calculate the value
+ names = []
+ if not hasattr(cls, "__slots__"):
+ # This class has no slots
+ pass
+ else:
+ # Slots found -- gather slot names from all base classes
+ for c in cls.__mro__:
+ if "__slots__" in c.__dict__:
+ slots = c.__dict__['__slots__']
+ # if class has a single slot, it can be given as a string
+ if isinstance(slots, basestring):
+ slots = (slots,)
+ for name in slots:
+ # special descriptors
+ if name in ("__dict__", "__weakref__"):
+ continue
+ # mangled names
+ elif name.startswith('__') and not name.endswith('__'):
+ names.append('_%s%s' % (c.__name__, name))
+ else:
+ names.append(name)
+
+ # Cache the outcome in the class if at all possible
+ try:
+ cls.__slotnames__ = names
+ except:
+ pass # But don't die if we can't
+
+ return names
+
+# A registry of extension codes. This is an ad-hoc compression
+# mechanism. Whenever a global reference to <module>, <name> is about
+# to be pickled, the (<module>, <name>) tuple is looked up here to see
+# if it is a registered extension code for it. Extension codes are
+# universal, so that the meaning of a pickle does not depend on
+# context. (There are also some codes reserved for local use that
+# don't have this restriction.) Codes are positive ints; 0 is
+# reserved.
+
+_extension_registry = {} # key -> code
+_inverted_registry = {} # code -> key
+_extension_cache = {} # code -> object
+# Don't ever rebind those names: cPickle grabs a reference to them when
+# it's initialized, and won't see a rebinding.
+
+def add_extension(module, name, code):
+ """Register an extension code."""
+ code = int(code)
+ if not 1 <= code <= 0x7fffffff:
+ raise ValueError, "code out of range"
+ key = (module, name)
+ if (_extension_registry.get(key) == code and
+ _inverted_registry.get(code) == key):
+ return # Redundant registrations are benign
+ if key in _extension_registry:
+ raise ValueError("key %s is already registered with code %s" %
+ (key, _extension_registry[key]))
+ if code in _inverted_registry:
+ raise ValueError("code %s is already in use for key %s" %
+ (code, _inverted_registry[code]))
+ _extension_registry[key] = code
+ _inverted_registry[code] = key
+
+def remove_extension(module, name, code):
+ """Unregister an extension code. For testing only."""
+ key = (module, name)
+ if (_extension_registry.get(key) != code or
+ _inverted_registry.get(code) != key):
+ raise ValueError("key %s is not registered with code %s" %
+ (key, code))
+ del _extension_registry[key]
+ del _inverted_registry[code]
+ if code in _extension_cache:
+ del _extension_cache[code]
+
+def clear_extension_cache():
+ _extension_cache.clear()
+
+# Standard extension code assignments
+
+# Reserved ranges
+
+# First Last Count Purpose
+# 1 127 127 Reserved for Python standard library
+# 128 191 64 Reserved for Zope
+# 192 239 48 Reserved for 3rd parties
+# 240 255 16 Reserved for private use (will never be assigned)
+# 256 Inf Inf Reserved for future assignment
+
+# Extension codes are assigned by the Python Software Foundation.