[Python-ideas] Question about `list.insert`

[Ryan]

The reason C++ has so many data types is for performance reasons. If you have a constant list of items, you use a tuple. If you know the list isn't going to exceed a certain length, you use arrays. If you're mainly going to be iterating through it, you use list. Otherwise, you use vector.

The reason Python doesn't need to worry about that is because it has entirely different goals.

Antoine Pitrou <solipsis at pitrou.net> wrote:
>On Sat, 8 Feb 2014 05:00:24 +1100
>Chris Angelico <rosuav at gmail.com> wrote:
>> On Sat, Feb 8, 2014 at 1:59 AM, Antoine Pitrou <solipsis at pitrou.net>
>wrote:
>> > On Fri, 7 Feb 2014 22:45:33 +1100
>> > Chris Angelico <rosuav at gmail.com> wrote:
>> >> But apart from
>> >> maybe reducing the memory copying (the same optimization could
>mean
>> >> that repeated pop(0) calls would incur less copying, too), there's
>not
>> >> a huge gain.
>> >
>> > If you think switching from O(n**2) to O(n) isn't a huge gain, then
>> > indeed :-)
>> >
>> 
>> Sure, that would be a huge gain. But anyone who's repeatedly calling
>> pop(0) followed by insert(0,x) should be using deque rather than
>list.
>
>Indeed, since deque exists, it is the reasonable answer.
>
>This whole discussion happens in a hypothetical setting where deque
>wouldn't exist and there would be an opportunity to make list a
>one-size-fits-all sequence type.
>
>(note that my personal opinion is that built-in Python data types
>should
>be sufficiently powerful to cater for most use cases, rather than build
>a whole array of specialized collection types as in Java or C++)
>
>Regards
>
>Antoine.
>
>
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