List replication operator

Fri May 25 01:30:36 EDT 2018

On 25May2018 02:25, Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:
>On 2018年5月24日 15:12:09 -0400, Ned Batchelder wrote:
>> On 5/24/18 2:17 PM, Steven D'Aprano wrote:
>[...]
>>> 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
>>You might be right: on further thought, I think I want deep copies, not
>shallow.
>>Originally I thought that deep copies was an YAGNI. Have you *ever* seen
>anyone complain that * didn't make a deep copy of the list contents? I
>never have. But then I realised that if this works, people will surely
>try to use it to make three-dimensional lists as well as two, and for
>that we need deep copies.

In the deep copy scenario I am far far less opposed - _that_ is practically 
exponential memory use, and so the "**" is much more apt :-)
I think I'm basicly against a shallow copy and not against a deep copy, because 
the shallow copy only pushes the issue out one layer.
So, how to various forms of multidimensional lists play out as code?
Cheers,
Cameron Simpson <cs at cskk.id.au>