Move _better_reduce from copy.py to copy_reg.py, and also use it in

pickle.py, where it makes save_newobj() unnecessary.  Tests pass.

Lib/copy.py

@@ -51,7 +51,7 @@ __getstate__() and __setstate__().  See the documentation for module
 # XXX need to support copy_reg here too...
 
 import types
-from pickle import _slotnames
+from copy_reg import _better_reduce
 
 class Error(Exception):
     pass
@@ -89,46 +89,6 @@ def copy(x):
     else:
         y = copierfunction(x)
     return y
-
-def __newobj__(cls, *args):
-    return cls.__new__(cls, *args)
-
-def _better_reduce(obj):
-    cls = obj.__class__
-    getnewargs = getattr(obj, "__getnewargs__", None)
-    if getnewargs:
-        args = getnewargs()
-    else:
-        args = ()
-    getstate = getattr(obj, "__getstate__", None)
-    if getstate:
-        try:
-            state = getstate()
-        except TypeError, err:
-            # XXX Catch generic exception caused by __slots__
-            if str(err) != ("a class that defines __slots__ "
-                            "without defining __getstate__ "
-                            "cannot be pickled"):
-                raise # Not that specific exception
-            getstate = None
-    if not getstate:
-        state = getattr(obj, "__dict__", None)
-        names = _slotnames(cls)
-        if names:
-            slots = {}
-            nil = []
-            for name in names:
-                value = getattr(obj, name, nil)
-                if value is not nil:
-                    slots[name] = value
-            if slots:
-                state = (state, slots)
-    listitems = dictitems = None
-    if isinstance(obj, list):
-        listitems = iter(obj)
-    elif isinstance(obj, dict):
-        dictitems = obj.iteritems()
-    return __newobj__, (cls,) + args, state, listitems, dictitems
     
 
 _copy_dispatch = d = {}

Lib/copy_reg.py

@@ -69,6 +69,84 @@ def _reduce(self):
     else:
         return _reconstructor, args
 
+# A better version of _reduce, used by copy and pickle protocol 2
+
+def __newobj__(cls, *args):
+    return cls.__new__(cls, *args)
+
+def _better_reduce(obj):
+    cls = obj.__class__
+    getnewargs = getattr(obj, "__getnewargs__", None)
+    if getnewargs:
+        args = getnewargs()
+    else:
+        args = ()
+    getstate = getattr(obj, "__getstate__", None)
+    if getstate:
+        try:
+            state = getstate()
+        except TypeError, err:
+            # XXX Catch generic exception caused by __slots__
+            if str(err) != ("a class that defines __slots__ "
+                            "without defining __getstate__ "
+                            "cannot be pickled"):
+                raise # Not that specific exception
+            getstate = None
+    if not getstate:
+        state = getattr(obj, "__dict__", None)
+        names = _slotnames(cls)
+        if names:
+            slots = {}
+            nil = []
+            for name in names:
+                value = getattr(obj, name, nil)
+                if value is not nil:
+                    slots[name] = value
+            if slots:
+                state = (state, slots)
+    listitems = dictitems = None
+    if isinstance(obj, list):
+        listitems = iter(obj)
+    elif isinstance(obj, dict):
+        dictitems = obj.iteritems()
+    return __newobj__, (cls,) + args, state, listitems, dictitems
+
+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__:
+                names += [name for name in c.__dict__["__slots__"]
+                               if name not in ("__dict__", "__weakref__")]
+
+    # 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

Lib/pickle.py

@@ -27,7 +27,7 @@ Misc variables:
 __version__ = "$Revision$"       # Code version
 
 from types import *
-from copy_reg import dispatch_table, _reconstructor
+from copy_reg import dispatch_table, _reconstructor, _better_reduce
 from copy_reg import _extension_registry, _inverted_registry, _extension_cache
 import marshal
 import sys
@@ -310,10 +310,7 @@ class Pickler:
             if self.proto >= 2:
                 # Protocol 2 can do better than the default __reduce__
                 if reduce is object.__reduce__:
-                    reduce = None
-                if not reduce:
-                    self.save_newobj(obj)
-                    return
+                    reduce = _better_reduce
             if not reduce:
                 raise PicklingError("Can't pickle %r object: %r" %
                                     (t.__name__, obj))
@@ -433,86 +430,6 @@ class Pickler:
             save(state)
             write(BUILD)
 
-    def save_newobj(self, obj):
-        # Save a new-style class instance, using protocol 2.
-        assert self.proto >= 2          # This only works for protocol 2
-        t = type(obj)
-        getnewargs = getattr(obj, "__getnewargs__", None)
-        if getnewargs:
-            args = getnewargs()         # This better not reference obj
-        else:
-            args = ()
-
-        save = self.save
-        write = self.write
-
-        self.save(t)
-        save(args)
-        write(NEWOBJ)
-        self.memoize(obj)
-
-        if isinstance(obj, list):
-            self._batch_appends(iter(obj))
-        elif isinstance(obj, dict):
-            self._batch_setitems(obj.iteritems())
-
-        getstate = getattr(obj, "__getstate__", None)
-
-        if getstate:
-            # A class may define both __getstate__ and __getnewargs__.
-            # If they are the same function, we ignore __getstate__.
-            # This is for the benefit of protocols 0 and 1, which don't
-            # use __getnewargs__.  Note that the only way to make them
-            # the same function is something like this:
-            #
-            #   class C(object):
-            #       def __getstate__(self):
-            #           return ...
-            #       __getnewargs__ = __getstate__
-            #
-            # No tricks are needed to ignore __setstate__; it simply
-            # won't be called when we don't generate BUILD.
-            # Also note that when __getnewargs__ and __getstate__ are
-            # the same function, we don't do the default thing of
-            # looking for __dict__ and slots either -- it is assumed
-            # that __getnewargs__ returns all the state there is
-            # (which should be a safe assumption since __getstate__
-            # returns the *same* state).
-            if getstate == getnewargs:
-                return
-
-            try:
-                state = getstate()
-            except TypeError, err:
-                # XXX Catch generic exception caused by __slots__
-                if str(err) != ("a class that defines __slots__ "
-                                "without defining __getstate__ "
-                                "cannot be pickled"):
-                    raise # Not that specific exception
-                getstate = None
-
-        if not getstate:
-            state = getattr(obj, "__dict__", None)
-            if not state:
-                state = None
-            # If there are slots, the state becomes a tuple of two
-            # items: the first item the regular __dict__ or None, and
-            # the second a dict mapping slot names to slot values
-            names = _slotnames(t)
-            if names:
-                slots = {}
-                nil = []
-                for name in names:
-                    value = getattr(obj, name, nil)
-                    if value is not nil:
-                        slots[name] = value
-                if slots:
-                    state = (state, slots)
-
-        if state is not None:
-            save(state)
-            write(BUILD)
-
     # Methods below this point are dispatched through the dispatch table
 
     dispatch = {}
@@ -713,7 +630,8 @@ class Pickler:
             tmp = []
             for i in r:
                 try:
-                    tmp.append(items.next())
+                    x = items.next()
+                    tmp.append(x)
                 except StopIteration:
                     items = None
                     break
@@ -865,42 +783,6 @@ class Pickler:
 
 # Pickling helpers
 
-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__:
-                names += [name for name in c.__dict__["__slots__"]
-                               if name not in ("__dict__", "__weakref__")]
-
-    # 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
-
 def _keep_alive(x, memo):
     """Keeps a reference to the object x in the memo.