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Update PEP 3154 after PEP 3155 has been accepted.

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Antoine Pitrou 2011-12-02 20:19:29 +01:00
parent 3c89c9c913
commit 4ca9074870
1 changed files with 16 additions and 23 deletions
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pep-3154.txt
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@ -71,27 +71,20 @@ arguments can not be pickled (or, rather, unpickled) [3]_. Both a new
special method (``__getnewargs_ex__`` ?) and a new opcode (NEWOBJEX ?)
are needed.
Serializing more callable objects
---------------------------------
Serializing more "lookupable" objects
-------------------------------------
Currently, only module-global functions are serializable.
Multiprocessing has custom support for pickling other callables such
as bound methods [4]_. This support could be folded in the protocol,
and made more efficient through a new GETATTR opcode.
For some kinds of objects, it only makes sense to serialize them by name
(for example classes and functions). By default, pickle is only able to
serialize module-global functions and classes by name. Supporting other
kinds of objects, such as unbound methods [4]_, is a common request.
Actually, third-party support for some of them, such as bound methods,
is implemented in the multiprocessing module [5]_.
Serializing "pseudo-global" objects
-----------------------------------
Objects which are not module-global, but should be treated in a
similar fashion -- such as unbound methods [5]_ or nested classes --
cannot currently be pickled (or, rather, unpickled) because the pickle
protocol does not correctly specify how to retrieve them. One
solution would be through the adjunction of a ``__namespace__`` (or
``__qualname__``) to all class and function objects, specifying the
full "path" by which they can be retrieved. For globals, this would
generally be ``"{}.{}".format(obj.__module__, obj.__name__)``. Then a
new opcode can resolve that path and push the object on the stack,
similarly to the GLOBAL opcode.
:pep:`3155` now makes it possible to lookup many more objects by name.
Generalizing the GLOBAL opcode to accept dot-separated names, or adding
a special GETATTR opcode, would allow the standard pickle implementation
to support, in an efficient way, all those kinds of objects.
Binary encoding for all opcodes
-------------------------------
@ -131,12 +124,12 @@ References
.. [3] "pickle/copyreg doesn't support keyword only arguments in __new__":
http://bugs.python.org/issue4727
.. [4] Lib/multiprocessing/forking.py:
http://hg.python.org/cpython/file/baea9f5f973c/Lib/multiprocessing/forking.py#l54
.. [5] "pickle should support methods":
.. [4] "pickle should support methods":
http://bugs.python.org/issue9276
.. [5] Lib/multiprocessing/forking.py:
http://hg.python.org/cpython/file/baea9f5f973c/Lib/multiprocessing/forking.py#l54
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