On 5/24/18 2:17 PM, Steven D'Aprano wrote:
Python has a sequence replication operator:py> [1, 2]*3 [1, 2, 1, 2, 1, 2] Unfortunately, it is prone to a common "gotcha": py> x = [[]]*5 # make a multi-dimensional list py> x [[], [], [], [], []] py> x[0].append(1) py> x [[1], [1], [1], [1], [1]] The reason for this behaviour is that * does not copy the original list's items, it simply replicates the references to the items. So we end up with a new list containing five references to the same inner list. This is not a bug and changing the behaviour is not an option. But what do people think about proposing a new list replication with copy operator? [[]]**5 would return a new list consisting of five shallow copies of the inner list.
"shallow" will be the next problem. Do we also need this?: [[[]]]***5 # j/k --Ned. -- https://mail.python.org/mailman/listinfo/python-list
