pickling the objects returned by array.array()

John Machin sjmachin at lexicon.net
Thu Sep 1 15:48:24 CEST 2005


Googling for "pickle array" in comp.lang.python yields old messages that 
show a PickleError -- plus one message where Alex Martelli writes "I am 
but an egg" :O)
Looks like arrays are NOW (2.4.1) pickleable but not unpickleable -- see 
below.
I appreciate that arrays are inherently not pickleable because of the 
type code.
However:
(1) Anyone know why/when the world changed?
(2) If we had alternative constructors like array.iarray(contents) in 
parallel to array.array('i', contents), those objects could be 
pickled/unpickled -- yes/no?

Cheers,
John
====================
Python 2.4.1 (#65, Mar 30 2005, 09:13:57) [MSC v.1310 32 bit (Intel)] on 
win32
Type "help", "copyright", "credits" or "license" for more information.
 >>> import pickle, array
 >>> class Foo(object):
...    pass
...
 >>> foo = Foo()
 >>> foo.ia = array.array('i', [3,2,1])
 >>> foo.ia
array('i', [3, 2, 1])
 >>> s = pickle.dumps(foo, -1)
 >>> bar = pickle.loads(s)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "C:\Python24\lib\pickle.py", line 1394, in loads
    return Unpickler(file).load()
  File "C:\Python24\lib\pickle.py", line 872, in load
    dispatch[key](self)
  File "C:\Python24\lib\pickle.py", line 1097, in load_newobj
    obj = cls.__new__(cls, *args)
TypeError: array() takes at least 1 argument (0 given)
===========



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