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From: Terry Reedy on 27 Jan 2010 17:15
On 1/27/2010 12:32 PM, Antoine Pitrou wrote:
> Le Wed, 27 Jan 2010 02:20:53 -0800, Floris Bruynooghe a écrit :
>>
>> Is a list or tuple better or more efficient in these situations?
>
> Tuples are faster to allocate (they are allocated in one single step) and
> quite a bit smaller too.
> In some situations, in Python 2.7 and 3.1, they can also be ignored by
> the garbage collector, yielding faster collections.
>
> (not to mention that they are hashable, which can be useful)

Constant tuples (a tuple whose members are all seen as constants by the
compiler) are now pre-compiled and constructed once and put into the
code object as such rather than re-constructed with each run of the code.

>>> from dis import dis
>>> def l(): return [1,2,3]

>>> def t(): return 1,2,3

>>> dis(l)
1 0 LOAD_CONST 1 (1)
3 LOAD_CONST 2 (2)
6 LOAD_CONST 3 (3)
9 BUILD_LIST 3
12 RETURN_VALUE
>>> dis(t)
1 0 LOAD_CONST 4 ((1, 2, 3))
3 RETURN_VALUE
>>> # 3.1

Terry Jan Reedy


From: Floris Bruynooghe on 28 Jan 2010 02:32
On Jan 27, 10:15 pm, Terry Reedy <tjre...(a)udel.edu> wrote:
> On 1/27/2010 12:32 PM, Antoine Pitrou wrote:
>
> > Le Wed, 27 Jan 2010 02:20:53 -0800, Floris Bruynooghe a écrit :
>
> >> Is a list or tuple better or more efficient in these situations?
>
> > Tuples are faster to allocate (they are allocated in one single step) and
> > quite a bit smaller too.

Thanks for all the answers! This is what I was expecting but it's
nice to see it confirmed.

Regards
Floris
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