New submission from Michael Seifert: When using `copy.copy` to copy an `itertools.chain` instance the results can be weird. For example
>>> from itertools import chain >>> from copy import copy >>> a = chain([1,2,3], [4,5,6]) >>> b = copy(a) >>> next(a) # looks okay 1 >>> next(b) # jumps to the second iterable, not okay? 4 >>> tuple(a) (2, 3) >>> tuple(b) (5, 6) I don't really want to "copy.copy" such an iterator (I would either use `a, b = itertools.tee(a, 2)` or `b = a` depending on the use-case). This just came up because I investigated how pythons iterators behave when copied, deepcopied or pickled because I want to make the iterators in my extension module behave similarly. ---------- components: Library (Lib) messages: 290106 nosy: MSeifert priority: normal severity: normal status: open title: itertools.chain behaves strangly when copied with copy.copy type: behavior versions: Python 3.5, Python 3.6 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue29897> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
