On Wed, Feb 10, 2010 at 9:12 AM, Mathias Panzenböck <grosser.meister.morti@gmx.net> wrote:
On 02/10/2010 11:39 AM, wxyarv wrote:
what about another method clone() (or copy())? i think this maybe useful either.
l1 = [1, 2, 3] l2 = l1[:] l3 = list(l1) _______________________________________________ Python-ideas mailing list Python-ideas@python.org http://mail.python.org/mailman/listinfo/python-ideas
Yes, I plan to ask for copy() as well, when the bug tracker opens up for 3.3, 3.4, etc. The issue is not, "Is there already a way to do this?" but rather, "Can we have consistent interfaces in the sequence types and collections where possible and appropriate?" dict() and set() already support both clear() and copy() methods. Previous posters have pointed to the disconnect and showed the problem of having to test if a given iterable supports the clear() method before calling it, in functions that take any iterable. Also, for what it's worth: s1 = set() s2 = s1.copy() is faster than s1 = set() s2 = set(s1) (and also for dict()) probably because the first is specifically-written for the copy operation whereas the second actually iterates over s1, one item at a time. (At least I think that's what's going on). I suppose that a list().copy() method might also be faster than the other two approaches to copy a list. Lastly, for completeness, I suppose copy() might be appropriate for both tuple and deque as well. -- Gerald Britton