[Python-checkins] python/dist/src/Lib pickle.py,1.131,1.132

[gvanrossum@users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1:/tmp/cvs-serv25315

Modified Files:
	pickle.py 
Log Message:
Add a magical feature to save_reduce so that __reduce__ can cause
NEWOBJ to be generated.


Index: pickle.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/pickle.py,v
retrieving revision 1.131
retrieving revision 1.132
diff -C2 -d -r1.131 -r1.132
*** pickle.py	31 Jan 2003 16:43:39 -0000	1.131
--- pickle.py	31 Jan 2003 16:51:45 -0000	1.132
***************
*** 366,372 ****
          write = self.write
  
!         save(func)
!         save(args)
!         write(REDUCE)
  
          if state is not None:
--- 366,409 ----
          write = self.write
  
!         # Protocol 2 special case: if func's name is __newobj__, use NEWOBJ
!         if self.proto >= 2 and getattr(func, "__name__", "") == "__newobj__":
!             # A __reduce__ implementation can direct protocol 2 to
!             # use the more efficient NEWOBJ opcode, while still
!             # allowing protocol 0 and 1 to work normally.  For this to
!             # work, the function returned by __reduce__ should be
!             # called __newobj__, and its first argument should be a
!             # new-style class.  The implementation for __newobj__
!             # should be as follows, although pickle has no way to
!             # verify this:
!             #
!             # def __newobj__(cls, *args):
!             #     return cls.__new__(cls, *args)
!             #
!             # Protocols 0 and 1 will pickle a reference to __newobj__,
!             # while protocol 2 (and above) will pickle a reference to
!             # cls, the remaining args tuple, and the NEWOBJ code,
!             # which calls cls.__new__(cls, *args) at unpickling time
!             # (see load_newobj below).  If __reduce__ returns a
!             # three-tuple, the state from the third tuple item will be
!             # pickled regardless of the protocol, calling __setstate__
!             # at unpickling time (see load_build below).
!             #
!             # Note that no standard __newobj__ implementation exists;
!             # you have to provide your own.  This is to enforce
!             # compatibility with Python 2.2 (pickles written using
!             # protocol 0 or 1 in Python 2.3 should be unpicklable by
!             # Python 2.2).
!             cls = args[0]
!             if not hasattr(cls, "__new__"):
!                 raise PicklingError(
!                     "args[0] from __newobj__ args has no __new__")
!             args = args[1:]
!             save(cls)
!             save(args)
!             write(NEWOBJ)
!         else:
!             save(func)
!             save(args)
!             write(REDUCE)
  
          if state is not None:
***************
*** 376,380 ****
      def save_newobj(self, obj):
          # Save a new-style class instance, using protocol 2.
-         # XXX This is still experimental.
          assert self.proto >= 2          # This only works for protocol 2
          t = type(obj)
--- 413,416 ----