using of copy.copy for simple iterators is forbidden
>>> import copy
>>> copy.copy(iter([1, 2, 3]))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/andrew/projects/py3k/Lib/copy.py", line 96, in copy
return _reconstruct(x, rv, 0)
File "/home/andrew/projects/py3k/Lib/copy.py", line 284, in _reconstruct
y = callable(*args)
File "/home/andrew/projects/py3k/Lib/copyreg.py", line 88, in __newobj__
return cls.__new__(cls, *args)
TypeError: object.__new__(list_iterator) is not safe, use
list_iterator.__new__()
That behavior is safe and clean.
But it's possible to copy iterator objects returned by itertools functions:
>>> i = itertools.chain([1, 2], [3, 4, 5])
>>> i.__next__()
1
>>> j = copy.copy(i)
>>> j.__next__()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
StopIteration
>>> i.__next__()
2
Looks like itertools object should be protected from usage like that.
Folks, what are you think about?
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