Add posting-date. Add note about the copy module. Remove TBD -- this

PEP is complete AFAIAC.

pep-0307.txt

@@ -7,7 +7,7 @@ Status: Active
 Type: Standards Track
 Content-Type: text/plain
 Created: 31-Jan-2003
-Post-History: None
+Post-History: 7-Feb-2003
 
 
 Introduction
@@ -599,9 +599,49 @@ Extension registry API
     It is up to applications to respect these.
 
 
-TBD
+The copy module
 
-    The rest of this PEP is still under construction!
+    Traditionally, the copy module has supported an extended subset of
+    the pickling APIs for customizing the copy() and deepcopy()
+    operations.
+
+    In particular, besides checking for a __copy__ or __deepcopy__
+    method, copy() and deepcopy() have always looked for __reduce__,
+    and for classic classes, have looked for __getinitargs__,
+    __getstate__ and __setstate__.
+
+    In Python 2.2, the default __reduce__ inherited from 'object' made
+    copying simple new-style classes possible, but slots and various
+    other special cases were not covered.
+
+    In Python 2.3, several changes are made to the copy module:
+
+    - The four- and five-argument return values of __reduce__ are
+      supported.
+
+    - Before looking for a __reduce__ method, the
+      copy_reg.dispatch_table is consulted, just like for pickling.
+
+    - When the __reduce__ method is inherited from object, it is
+      (unconditionally) replaced by a better one that uses the same 
+      APIs as pickle protocol 2: __getnewargs__, __getstate__, and
+      __setstate__, handling list and dict subclasses, and handling
+      slots.
+
+    As a consequence of the latter change, certain new-style classes
+    that were copyable under Python 2.2 are not copyable under Python
+    2.3.  (These classes are also not picklable using pickle protocol
+    2.)  A minimal example of such a class:
+
+        class C(object):
+            def __new__(cls, a):
+                return object.__new__(cls)
+
+    The problem only occurs when __new__ is overridden and has at
+    least one mandatory argument in addition to the class argument.
+
+    To fix this, a __getnewargs__ method should be added that returns
+    the appropriate argument tuple (excluding the class).
 
 
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