[PLUG] python and deepcopy

[Jeff Abrahamson <jeff@purple.com>]

I have a not very deep data structure.  It just contains a dictionary
and some lists, nothing to scary.  But when I try to deepcopy it, I
get bad errors (below).

I've googled and found a barely related bug reported only once, so I
don't really believe this is likely a python bug.

Anyone seen this before?  Any thoughts?


    >>> c=copy.deepcopy(b)
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
      File "/usr/lib/python2.3/copy.py", line 179, in deepcopy
	y = copier(x, memo)
      File "/usr/lib/python2.3/copy.py", line 307, in _deepcopy_inst
	state = deepcopy(state, memo)
      File "/usr/lib/python2.3/copy.py", line 179, in deepcopy
	y = copier(x, memo)
      File "/usr/lib/python2.3/copy.py", line 270, in _deepcopy_dict
	y[deepcopy(key, memo)] = deepcopy(value, memo)
      File "/usr/lib/python2.3/copy.py", line 179, in deepcopy
	y = copier(x, memo)
      File "/usr/lib/python2.3/copy.py", line 243, in _deepcopy_list
	y.append(deepcopy(a, memo))
      File "/usr/lib/python2.3/copy.py", line 179, in deepcopy
	y = copier(x, memo)
      File "/usr/lib/python2.3/copy.py", line 243, in _deepcopy_list
	y.append(deepcopy(a, memo))
      File "/usr/lib/python2.3/copy.py", line 206, in deepcopy
	y = _reconstruct(x, rv, 1, memo)
      File "/usr/lib/python2.3/copy.py", line 338, in _reconstruct
	y = callable(*args)
      File "/usr/lib/python2.3/copy_reg.py", line 92, in __newobj__
	return cls.__new__(cls, *args)
    TypeError: function() takes at least 2 arguments (0 given)
    >>> 


Some of the structures to be copied are lists of lambda functions.
Here's something else that fails:

    jeff@asterix:jeff $ python
    Python 2.3.4 (#2, Jul  5 2004, 09:15:05)
    [GCC 3.3.4 (Debian 1:3.3.4-2)] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> b=[lambda x: x*x, lambda x: 2*x]
    >>> import copy
    >>> c=copy.copy(b)
    >>> c
    [<function <lambda> at 0x4021fd4c>, <function <lambda> at 0x4021fdbc>]
    >>> c[0](3)
    9
    >>> c[1](3)
    6
    >>> d = copy.deepcopy(b)
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
      File "/usr/lib/python2.3/copy.py", line 179, in deepcopy
	y = copier(x, memo)
      File "/usr/lib/python2.3/copy.py", line 243, in _deepcopy_list
	y.append(deepcopy(a, memo))
      File "/usr/lib/python2.3/copy.py", line 206, in deepcopy
	y = _reconstruct(x, rv, 1, memo)
      File "/usr/lib/python2.3/copy.py", line 338, in _reconstruct
	y = callable(*args)
      File "/usr/lib/python2.3/copy_reg.py", line 92, in __newobj__
	return cls.__new__(cls, *args)
    TypeError: function() takes at least 2 arguments (0 given)
    >>>

This doesn't seem right, though.

-- 
 Jeff

 Jeff Abrahamson  <http://www.purple.com/jeff/>    +1 215/837-2287
 GPG fingerprint: 1A1A BA95 D082 A558 A276  63C6 16BF 8C4C 0D1D AE4B

 A cool book of games, highly worth checking out:
 http://www.amazon.com/exec/obidos/ASIN/1931686963/purple-20

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