Re: [Pyobjc-dev] pickled Objective-C objects

[Just v. R. <ju...@le...>]

A couple of quick thoughts.

Guido and Tim Peters have been doing a lot of work on pickle very
recently (for 2.3, it's in 2.3a2). I don't know the details but it has
to do with new style classes, so probably affects PyObjC (in a good way,
hopefully ;-). The original boolean dump flag denoting text/binary has
been upgraded to mean the protocol version: protocol 0 is the text
version, 1 is the original binary protocol, 2 is a new binary protocol,
which apparently has better (more efficient) support for new style
objects. I'm not sure how it all works, but if it would make things
easier, I would be happy with a 2.3-only solution.

I noticed that unpickling a new style object causes cls.__new__ to be
called. This currently does not work for ObjC classes as they insist on
being allocated with alloc(). However, ObjC's alloc/init protocol is in
many ways equivalent to Python's __new__/__init__ protocol, so as a
first step towards supporting pickling, I propose to make __new__ an
alias for alloc, and move the "TypeError: Use class methods to
instantiate new Objective-C objects" exception to the __init__/tp_init
method. Calling an ObjC class will then still result in that exception,
while still properly supporting __new__.

Just