return \@array or @array

[Daniel de Oliveira Mantovani]

Abigail, the point was just show the reference performance. The point
is, Jérôme Étévé said:
"I'm still not quite sure about the real benefit of return \@array though."
And my answer was just for it.

On 12 September 2013 17:04, Abigail <abigail at abigail.be> wrote:
> On Thu, Sep 12, 2013 at 04:23:40PM -0300, Daniel de Oliveira Mantovani wrote:
>> On 12 September 2013 16:14, Abigail <abigail at abigail.be> wrote:
>> > On Thu, Sep 12, 2013 at 02:05:13PM -0300, Daniel de Oliveira Mantovani wrote:
>> >> On 12 September 2013 13:05, Jérôme Étévé <jerome.eteve at gmail.com> wrote:
>> >> > Great :)
>> >> >
>> >> > so now:
>> >> >
>> >> > use Devel::Peek;
>> >> >
>> >> > sub foo{
>> >> >     my @foo = 0..2;
>> >> >     # Dump A
>> >> >     print Dump(\@foo);
>> >> >     return @foo;
>> >> > }
>> >> >
>> >> > my @foo = foo();
>> >> >
>> >> > # Dump B
>> >> > print Dump(\@foo);
>> >> >
>> >> > Prints quite interesting resutls. It shows both references are the
>> >> > same, with only the intermediate PVAV changing.
>> >> >
>> >> > I'm still not quite sure about the real benefit of return \@array though.
>> >>
>> >>
>> >> Because you are dumb like a stone,
>> >
>> > That doesn't seem to be called for.
>> >
>> >> [admin at localhost ~]$ time perl -E 'sub f {@a=1..9999999;return \@a}@b=f();'
>> >>
>> >> real    0m1.802s
>> >> user    0m1.433s
>> >> sys    0m0.364s
>> >> [admin at localhost ~]$ time perl -E 'sub f {@a=1..9999999;return @a}@b=f();'
>> >>
>> >> real    0m3.331s
>> >> user    0m2.695s
>> >> sys    0m0.621s
>> >
>> >
>> > Uhm, now you're just measuring half of the given program. It's not just
>> > about returning something from a method, it's *also* about looping over
>> > the elements. It turns out that returning a reference is still faster,
>> > but your benchmark doesn't show that.
>>
>> My benchmark does show that. Look again.
>>
>
>
> Can you point me out where in
>
>     sub f {@a=1..9999999;return \@a}@b=f();
>
> you are looping over the numbers 1 to 9999999?
>
>
>
> Abigail



-- 

-dom

--

Daniel de Oliveira Mantovani
Business Analytic Specialist
Perl Evangelist /Astrophysics hobbyist.
+55 11 9 8538-9897
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