How to clean an array

Perlish more-than-one-way

We hired Delphi/SQL programmer

as a Perl developer

Good programmer writes good code in every language

But lots of fun

sub clear{ my $template = shift @args; @{$self->{tokens}} = (); foreach (map {$_->{name}} @{$template->{si}}){ while (my $r = shift @{$self->{$_}->{res}}){} } }

Wat de fuck is dat?

sub clear{ my $template = shift @args; @{$self->{tokens}} = (); foreach (map {$_->{name}} @{$template->{si}}){ while (my $r = shift @{$self->{$_}->{res}}){} } } A subroutine to make an object empty

sub clear{ my $template = shift @args; @{$self->{tokens}} = (); foreach (map {$_->{name}} @{$template->{si}}){ while (my $r = shift @{$self->{$_}->{res}}){} } } Note this

Posted that piece to Moscow.pm mailing list

And we bacame crazy

1 while (my $r = shift @a) {}

2 splice @a;

3 delete(@a[0..$#a]);

4 grep {shift @a} @a;

5 @a = ();

5 @a = (); Boring!

6 undef @a;

ccn@ccn-laptop ~ $ perl -le 'my @a=(1,2,3); while(my $r = shift @a){}; print @a' ccn@ccn-laptop ~ $ perl -le 'my @a=(0,1,2,3); while(my $r = shift @a){}; print @a' 123

7 while(deﬁned(my $r = shift @a)) {}

ccn@ccn-laptop ~ $ perl -le 'my @a=(undef,1,2,3);while (deﬁned(my $r=shift @a)){};print @a' 123

Doesn’t work

Let’s make it useful

$str = "abcc{0}def"; @a = split //, $str; $c++ while(shift @a); say $c - 1; Calculate zero-ending string length

8 while(chomp $str) {};

9 while(@a) {shift @a}

10 shift @a while @a; Much better!

11 shift @a while @a and die;

12 shift @a while scalar @a;

13 $#a = -1 Who remembers?!

Bonus my @a = qw(oh eh); while (push(@a, shift @a)) {}; Endless sex loop

use Benchmark qw(:all :hireswallclock); my $size = 1000; Be cmpthese timethese -3, { nc '@a = ...' => sub { my @a = (('test')x$size); h m return; }, ar 'undef @a' => sub { my @a = (('test')x$size); undef @a; ke return; }, d '@a=()' => sub { my @a = (('test')x$size); @a = (); return; }, 'splice @a' => sub { my @a = (('test')x$size); splice @a; return; }, '$#a = -1' => sub { my @a = (('test')x$size); $#a = -1; return; }, 'shift @a while @a' => sub { my @a = (('test')x$size); shift @a while @a; return; }, 'delete @a[0..#$a]' => sub { my @a = (('test')x$size); delete(@a[0..$#a]); return; }, }; при $size=1000; shift @a while @a 2642/s -- -22% -44% -44% -45% -45% -45% delete @a[0..#$a] 3376/s 28% -- -28% -29% -29% -30% -30% splice @a 4722/s 79% 40% -- -0% -1% -2% -2%

TIMTOWTDI or die; Andrew Shitov talks.shitov.ru | andy@shitov.ru

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How to clean an array

by andy.sh on Jun 26, 2010

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How to clean an array — Presentation Transcript