return \@array or @array

[Abigail]

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