[Python-ideas] Length hinting and preallocation for container types

[Stefan Behnel]

Eli Bendersky, 08.03.2013 15:40:
> On Fri, Mar 8, 2013 at 6:04 AM, Daniel Holth wrote:
>> On Fri, Mar 8, 2013 at 8:35 AM, Antoine Pitrou wrote:
>>> Le Fri, 8 Mar 2013 08:18:07 -0500,
>>> Daniel Holth a écrit :
>>>> I am a fan of the proposal. Imagine you are programming for a
>>>> memory-constrained system. By telling the list how big it needs to be
>>>> you can save precious RAM.
>>>
>>> Is it an actual use case or are you just imagining it? :)
>>> I'm asking because, unless you are only allocating that list and all
>>> the objects contained it in it already exist, limiting the list's size
>>> won't do much for the process' memory occupation.
>>
>> It might help if it was a list of integers between -1 and 99 and
>> 1-character strings.
> 
> That's not what you should use lists for if memory consumption matters. Use
> http://docs.python.org/dev/library/array.html, especially if your integers
> are in such a limited range.

Yep, and regarding the second part, a string is a very efficient way to
store many 1-character strings.

Stefan