Re^3: shift vs @

They seem to be about the same. shift comes out slightly ahead in this test, perhaps because it simplifies the loop.

#!/usr/bin/perl

use warnings;
use strict;

use Benchmark;

timethese(1_000_000, {
  'use_shift' => sub { sub_with_shift(0..9) },
  'use_list' => sub { sub_with_list(0..9) },
  'use_direct' => sub { sub_with_direct(0..9) },
});

sub sub_with_shift
{
  my $sum = 0;
  while (@_)
  {
    $sum += shift;
  }
  $sum;
}

sub sub_with_list
{
  my(@a)=@_;
  my $sum = 0;
  $sum += $_
    for @a;
  $sum;
}

sub sub_with_direct
{
  my $sum = 0;
  $sum += $_
    for @_;
  $sum;
}
[download]

Benchmark: timing 1000000 iterations of use_direct, use_list, use_shift...
use_direct:  7 wallclock secs ( 6.48 usr + -0.01 sys =  6.47 CPU) @ 154559.51/s (n=1000000)
  use_list: 10 wallclock secs ( 9.85 usr +  0.06 sys =  9.91 CPU) @ 100908.17/s (n=1000000)
 use_shift:  6 wallclock secs ( 6.48 usr +  0.01 sys =  6.49 CPU) @ 154083.20/s (n=1000000)

--
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Comment on Re^3: shift vs @_ Select or Download Code

Replies are listed 'Best First'.
Re^4: shift vs @_ by Anonymous Monk on Oct 23, 2014 at 06:31 UTC
`#!/usr/bin/perl use warnings; use strict; use Benchmark; timethese(1_000_000, { 'use_shift' => sub { sub_with_shift(0..2) }, 'use_list' => sub { sub_with_list(0..2) }, 'use_direct' => sub { sub_with_direct(0..2) }, }); sub sub_with_shift { my ($one, $two, $three) = (shift, shift, shift); my $sum = $one+$two+$three; } sub sub_with_list { my ($one, $two, $three) = @_; my $sum = $one+$two+$three; } sub sub_with_direct { my $sum = $_[0] + $_[1] + $_[2]; }` [download] i think my example better reflects the core of the problem	[reply] [d/l]
Re^4: shift vs @_ by Anonymous Monk on Oct 23, 2014 at 06:33 UTC
`Sorry i forgot result Benchmark: timing 1000000 iterations of use_direct, use_list, use_shif +t... use_direct: 0 wallclock secs ( 0.57 usr + 0.00 sys = 0.57 CPU) @ 17 +54385.96/s (n=1000000) use_list: 1 wallclock secs ( 0.86 usr + 0.00 sys = 0.86 CPU) @ 11 +62790.70/s (n=1000000) use_shift: 2 wallclock secs ( 0.96 usr + 0.00 sys = 0.96 CPU) @ 10 +41666.67/s (n=1000000)` [download]	[reply] [d/l]