http://hg.python.org/peps/rev/d54015aaa32b changeset: 4006:d54015aaa32b user: Antoine Pitrou <solipsis@pitrou.net> date: Fri Dec 02 20:19:29 2011 +0100 summary: Update PEP 3154 after PEP 3155 has been accepted. files: pep-3154.txt | 37 ++++++++++++++++--------------------- 1 files changed, 16 insertions(+), 21 deletions(-) diff --git a/pep-3154.txt b/pep-3154.txt --- a/pep-3154.txt +++ b/pep-3154.txt @@ -71,27 +71,20 @@ 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 @@ .. [3] "pickle/copyreg doesn't support keyword only arguments in __new__": http://bugs.python.org/issue4727 -.. [4] Lib/multiprocessing/forking.py: +.. [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.p... -.. [5] "pickle should support methods": - http://bugs.python.org/issue9276 - Copyright ========= -- Repository URL: http://hg.python.org/peps