Perl 5.12
for everyday use
Sunday, December 5, 2010

5.12 isn’t like 5.10
perl5100delta
Sunday, December 5, 2010

5.12 isn’t like 5.10
- after 5.8, we had to wait 5 years for 5.10
perl5100delta
Sunday, December 5, 2010

5.12 isn’t like 5.10
- after 5.8, we had to wait 5 years for 5.10
- 5.12 came out 2 years after 5.10
perl5100delta
Sunday, December 5, 2010

5.12 is a Nice Change
perl5100delta
Sunday, December 5, 2010

5.12 is a Nice Change
- 5.10 was a huge set of changes
perl5100delta
Sunday, December 5, 2010

5.12 is a Nice Change
- 5.10 was a huge set of changes
- 5.12 is a lot smaller
perl5100delta
Sunday, December 5, 2010

5.12 is a Nice Change
- 5.10 was a huge set of changes
- 5.12 is a lot smaller
- 5.12 is not as compelling as 5.10
perl5100delta
Sunday, December 5, 2010

5.12 is a Nice Change
- 5.10 was a huge set of changes
- 5.12 is a lot smaller
- 5.12 is not as compelling as 5.10
- and that’s a good thing
perl5100delta
Sunday, December 5, 2010

5.12 is a Mixed Bag
perl5100delta
Sunday, December 5, 2010

5.12 is a Mixed Bag
- this talk isn’t just for beginners
perl5100delta
Sunday, December 5, 2010

5.12 is a Mixed Bag
- this talk isn’t just for beginners
- some of these changes are at the edges
perl5100delta
Sunday, December 5, 2010

5.12 is a Mixed Bag
- this talk isn’t just for beginners
- some of these changes are at the edges
- but they’re all practical
perl5100delta
Sunday, December 5, 2010

5.12 is a Mixed Bag
- this talk isn’t just for beginners
- some of these changes are at the edges
- but they’re all practical
- except for the ones that aren’t
perl5100delta
Sunday, December 5, 2010

By the way, 5.14...
perl5132delta
Sunday, December 5, 2010

By the way, 5.14...
- is going to be awesome
perl5132delta
Sunday, December 5, 2010

By the way, 5.14...
- is going to be awesome
- and available in about nine months
perl5132delta
Sunday, December 5, 2010

By the way, 5.14...
- is going to be awesome
- and available in about nine months
- and it’s going to be awesome
perl5132delta
Sunday, December 5, 2010

...and 5.10 is frozen.
perl5101delta
Sunday, December 5, 2010

...and 5.10 is frozen.
- 5.10 is the last release of the old way
perl5101delta
Sunday, December 5, 2010

...and 5.10 is frozen.
- 5.10 is the last release of the old way
- that means it got some features backported
perl5101delta
Sunday, December 5, 2010

...and 5.10 is frozen.
- 5.10 is the last release of the old way
- that means it got some features backported
- that will never happen again
perl5101delta
Sunday, December 5, 2010

...and 5.10 is frozen.
- 5.10 is the last release of the old way
- that means it got some features backported
- that will never happen again
- I’ll point out 5.12isms that got into 5.10.1
perl5101delta
Sunday, December 5, 2010

but enough about other versions
Sunday, December 5, 2010

let’s talk about 5.12
Sunday, December 5, 2010

First: A Warning
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
- use feature ‘mtfnpy’;
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
- use feature ‘mtfnpy’;
- use 5.012;
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
- use feature ‘mtfnpy’;
- use 5.012;
- read the perldoc
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
- use feature ‘mtfnpy’;
- use 5.012;
- read the perldoc I’m a perldoc
ref!
feature
Sunday, December 5, 2010

First: A Warning
- 5.12 is backwards compatible
- but adds new keywords and operators
- they’re not enabled by default
- use feature ‘mtfnpy’;
- use 5.012;
- read the perldoc
feature
Sunday, December 5, 2010

$old ~~ $new
- the smart match operator changed
also in 5.10.1
perlsyn
Sunday, December 5, 2010

~~
- no longer commutative; right side wins
- non-overloaded objects can’t be ~~ed
- still very complicated (23 behaviors)
- you won’t be using this every day
perldoc
Sunday, December 5, 2010

autodie
also in 5.10.1
autodie
Sunday, December 5, 2010

autodie
- like Fatal
also in 5.10.1
autodie
Sunday, December 5, 2010

autodie
- like Fatal
- but deadlier
also in 5.10.1
autodie
Sunday, December 5, 2010

autodie
open my $fh, ‘>‘, $filename;
while (<$fh>) {
...
}
close $fh;
autodie
Sunday, December 5, 2010

autodie
open my $fh, ‘>‘, $filename
or die “couldn’t open $filename: $!”;
while (<$fh>) {
...
}
close $fh
or die “couldn’t close $filename: $!”;
autodie
Sunday, December 5, 2010

autodie
use autodie;
open my $fh, ‘<‘, $filename;
while (<$fh>) {
...
}
close $fh;
autodie
Sunday, December 5, 2010

autodie
use autodie;
open my $fh, ‘>‘, $filename;
while (<$fh>) {
no autodie;
rmdir or warn “couldn’t remove $_: $!”;
}
close $fh;
autodie
Sunday, December 5, 2010

autodie problems
- autodie doesn’t affect print
- you must close filehandles explicitly
perldoc
Sunday, December 5, 2010

Unicode
Sunday, December 5, 2010

Perl is Good at Unicode
perlunicode
Sunday, December 5, 2010

Perl 5.12 is Better
perlunicode
Sunday, December 5, 2010

Perl 5.12 is Better
- Unicode 5.2
perlunicode
Sunday, December 5, 2010

Perl 5.12 is Better
- Unicode 5.2
- every character property is available
perlunicode
Sunday, December 5, 2010

Perl 5.12 is Better
- Unicode 5.2
- every character property is available
- X in regex is more sensible
perlunicode
Sunday, December 5, 2010

“The Unicode Bug”
perlunicode
Sunday, December 5, 2010

“The Unicode Bug”
- strings aren’t always treated as Unicode
perlunicode
Sunday, December 5, 2010

“The Unicode Bug”
- strings aren’t always treated as Unicode
- this causes weird bugs that take ages to find
perlunicode
Sunday, December 5, 2010

“The Unicode Bug”
- strings aren’t always treated as Unicode
- this causes weird bugs that take ages to find
- use feature ‘unicode_strings’;
perlunicode
Sunday, December 5, 2010

use feature ‘unicode_strings’;
perldoc
Sunday, December 5, 2010

use 5.12.0;
perldoc
Sunday, December 5, 2010

use 5.10.0;
perldoc
Sunday, December 5, 2010

use 5.10.0;
use feature qw(
say
state
switch
);
perldoc
Sunday, December 5, 2010

use 5.12.0;
perldoc
Sunday, December 5, 2010

use 5.12.0;
use feature qw(
say
state
switch
unicode_strings
);
perldoc
Sunday, December 5, 2010

use 5.12.0;
use feature qw(
say
state
switch
unicode_strings
);
use strict;
perldoc
Sunday, December 5, 2010

Container Improvements
Sunday, December 5, 2010

my %hash = (a => 1, b => 2);
while (my ($k, $v) = each %hash) {
say “value for $k is $v”;
}
Sunday, December 5, 2010

my %hash = (a => 1, b => 2);
while (my ($k, $v) = each %hash) {
say “value for $k is $v”;
}
value for a is 1
value for b is 2
Sunday, December 5, 2010

Sunday, December 5, 2010

my @array = qw(a b);
Sunday, December 5, 2010

my @array = qw(a b);
value for 0 is b
value for 1 is a
Sunday, December 5, 2010

my @array = qw(a b);
for my $k (0 .. $#array) {
say “value for $k is $array[$k]”;
}
value for 0 is b
value for 1 is a
Sunday, December 5, 2010

my @array = qw(a b);
while (my ($k, $v) = each @array) {
say “value for $k is $v”;
}
value for 0 is b
value for 1 is a
Sunday, December 5, 2010

my @array = qw(a b);
for my $k (0 .. $#array) {
say “value for $k is $array[$k]”;
}
my @array = qw(a b);
while (my ($k, $v) = each @array) {
say “value for $k is $v”;
}
Sunday, December 5, 2010

sub redump {
my ($href) = @_;
while (my ($k, $v) = each %hash) {
say “value for $k is $v”;
}
}
my %hash = (a => 1, b => 2);
while (my ($k, $v) = each %hash) {
print “== $k ==”;
redump(%hash);
}
Sunday, December 5, 2010

my @array = qw(a b);
while (my ($k, $v) = each @array) {
say “value for $k is $v”;
}
Sunday, December 5, 2010

my @array = qw(a b);
while (my ($k, $v) = each @array) {
say “value for $k is $v”;
do_something(@array);
}
Sunday, December 5, 2010

my @array = qw(a b);
while (my ($k, $v) = each @array) {
say “value for $k is $v”;
}
Sunday, December 5, 2010

my @array = qw(a b);
while (my ($k, $v) = each @array) {
my $string = $part_for_maybe_transient->bodyhandle->as_string;
my $transient_pos = _match_position($string, $Not_An_Error);
last unless defined $transient_pos;
my $permanent_pos = _match_position($string, $Really_An_Error);
my $orig_msg_pos = _match_position($string, $Returned_Message_Below);
last if _position_before($permanent_pos, $orig_msg_pos);
if (_position_before($transient_pos, $orig_msg_pos)) {
say “value for $k is $v”;
last if $message->effective_type eq ‘multipart/report’;
last if !$first_part
|| $first_part->effective_type ne ‘text/plain’;
my $string = $first_part->as_string;
last if length($string) > 3000;
# added return receipt (fix for bug #41870)
last if $string !~ /auto.{0,20}reply|return receipt
|vacation|(out|away|on holiday).*office/i;
$self->log(“looks like an autoreply, ignoring.”);
$self->{type} = “vacation autoreply”;
$self->{is_bounce} = 0;
return $self;
}
}
Sunday, December 5, 2010

AVOID
each @array
Sunday, December 5, 2010

local ??
Sunday, December 5, 2010

use Ancient::Utility qw(stuff);
my $result = do {
local $Ancient::Utility::WIDTH = 10;
stuff( $input );
};
Sunday, December 5, 2010

my $href = { a => 1, b => 2 };
my $result = do {
local $href->{a} = 3;
stuff( $href );
};
Sunday, December 5, 2010

my $href = { a => 1, b => 2 };
my $result = do {
delete local $href->{a};
stuff( $href );
};
Sunday, December 5, 2010

$]
Sunday, December 5, 2010

$[
Sunday, December 5, 2010

$[ - first index of array
perlvar
Sunday, December 5, 2010

$[ - first index of array
- so you can make $array[1] mean first
perlvar
Sunday, December 5, 2010

$[ - first index of array
- so you can make $array[1] mean first
- isn’t that awesome???
perlvar
Sunday, December 5, 2010

$[ - first index of array
- so you can make $array[1] mean first
- isn’t that awesome???
- yeah, about as awesome as Comic Sans
perlvar
Sunday, December 5, 2010

$[
$[ = 1;
for (1 .. $#array) {
...
}
perlvar
Sunday, December 5, 2010

$[
for ($[ .. $#array) {
...
}
perlvar
Sunday, December 5, 2010

$[
Assigned to $[. Are you some kind of
idiot or something? at -e line 123.
perlvar
Sunday, December 5, 2010

$[
Use of assignment to $[ is deprecated
at -e line 123.
perlvar
Sunday, December 5, 2010

More About Deprecations
Sunday, December 5, 2010

@INC
Sunday, December 5, 2010

@INC:
/usr/pkg/lib/perl5/5.8.0/i386-solaris
/usr/pkg/lib/perl5/5.8.0
/usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/site_perl/5.8.0
/usr/pkg/lib/perl5/site_perl
/usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/vendor_perl/5.8.0
/usr/pkg/lib/perl5/vendor_perl
perlvar
Sunday, December 5, 2010

@INC:
/usr/pkg/lib/perl5/5.8.0/i386-solaris
/usr/pkg/lib/perl5/5.8.0
/usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/site_perl/5.8.0
/usr/pkg/lib/perl5/site_perl
/usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/vendor_perl/5.8.0
/usr/pkg/lib/perl5/vendor_perl
perlvar
Sunday, December 5, 2010

@INC:
/usr/pkg/lib/perl5/site_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/site_perl/5.8.0
/usr/pkg/lib/perl5/site_perl
/usr/pkg/lib/perl5/vendor_perl/5.8.0/i386-solaris
/usr/pkg/lib/perl5/vendor_perl/5.8.0
/usr/pkg/lib/perl5/vendor_perl
/usr/pkg/lib/perl5/5.8.0/i386-solaris
/usr/pkg/lib/perl5/5.8.0
perlvar
Sunday, December 5, 2010

now we can remove stuff
from the core distribution
Sunday, December 5, 2010

Class::ISA
Pod::Plainer
Shell
Sunday, December 5, 2010

Class::ISA
Pod::Plainer
Shell
Switch
Sunday, December 5, 2010

… and …
Sunday, December 5, 2010

Sunday, December 5, 2010

my $x = get_input;
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
} else {
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
} else {
...
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
} else {
...
}
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
} else {
...
}
Sunday, December 5, 2010

my $x = get_input;
if ( $x >= 0 ) {
do_something for 0 .. $x;
} else {
die “Unimplemented”
}
Sunday, December 5, 2010

sub virtual_method { ... }
Sunday, December 5, 2010

sub method_I_will_write_later { ... }
Sunday, December 5, 2010

Unimplemented at Some::Library line 123
Sunday, December 5, 2010

AVOID
...
Sunday, December 5, 2010

AVOID
...
(except maybe in slides and pseudocode)
Sunday, December 5, 2010

sub virtual_method {
confess ‘...’
}
sub method_I_will_write_later {
confess ‘...’
}
Sunday, December 5, 2010

error message
improvements
Sunday, December 5, 2010

perldiag
Sunday, December 5, 2010

perldiag
Sunday, December 5, 2010

perldiag
Sunday, December 5, 2010

perl -MCGI -e’my $q = CGI->new;’
Unrecognized character xE2 in column
12 at -e line 1.
perldiag
Sunday, December 5, 2010

perl -MCGI -e’my $q = CGI->new;’
Unrecognized character xE2 in column
12 at -e line 1.
perl -MCGI -e’my $q = CGI­−->new;’
Unrecognized character xE2; marked
by <-- HERE after y $q = CGI<-- HERE
near column 12 at -e line 1.
perldiag
Sunday, December 5, 2010

My Favorite 5.10-ism?
$str = “Greetings, $name. Your last
login was $last. It is now $time.”;
Use of uninitialized value $time in
concatenation (.) or string at
hello.plx line 9.
perldiag
Sunday, December 5, 2010

My Favorite 5.12-ism?
if (length $input->{new_email}) {
$user->update_email(...);
}
perldiag
Sunday, December 5, 2010

My Favorite 5.12-ism?
if (length $input->{new_email}) {
$user->update_email(...);
}
Use of uninitialized value in length
at - line 3120.
perldiag
Sunday, December 5, 2010

My Favorite 5.12-ism?
if (length $input->{new_email}) {
$user->update_email(...);
}
perldiag
Sunday, December 5, 2010

overloading
Sunday, December 5, 2010

my $object = Object->new;
print $object;
Sunday, December 5, 2010

my $object = Object->new;
{
no overloading;
print $object;
}
Sunday, December 5, 2010

my $filename = get_filename;
if (-d $filename) {
handle_directory($filename);
}
Sunday, December 5, 2010

package Filename;
use overload ‘-X’ => sub {
my ($self, $test) = @_;
return $self->is_dir if $test eq ‘d’;
return $self->cd_able if $test eq ‘x’;
...;
};
Sunday, December 5, 2010

my $file = get_file;
if (-d $file) {
handle_directory($file);
}
Sunday, December 5, 2010

my $filename = get_file;
if (-d $file and -x _) {
handle_directory($file);
}
Sunday, December 5, 2010

my $filename = get_filename;
if (-d -x $filename) {
handle_directory($filename);
}
Sunday, December 5, 2010

AVOID
overload -X
Sunday, December 5, 2010

y2038
Sunday, December 5, 2010

Sunday, December 5, 2010

~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’
Sunday, December 5, 2010

~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
Sunday, December 5, 2010

~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
~$ perl5.10.0 -E ‘say scalar localtime 2**31’
Sunday, December 5, 2010

~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
~$ perl5.10.0 -E ‘say scalar localtime 2**31’
Fri Dec 13 15:45:52 1901
Sunday, December 5, 2010

Sunday, December 5, 2010

~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’
Sunday, December 5, 2010

~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
Sunday, December 5, 2010

~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
~$ perl5.12.0 -E ‘say scalar localtime 2**31’
Sunday, December 5, 2010

~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’
Mon Jan 18 22:14:07 2038
~$ perl5.12.0 -E ‘say scalar localtime 2**31’
Mon Jan 18 22:14:08 2038
Sunday, December 5, 2010

some non-everyday changes
Sunday, December 5, 2010

Method Resolution Order
A
B C
D
mro
Sunday, December 5, 2010

Method Resolution Order
A
- 5.8 : D, B, A, C
B C
D
mro
Sunday, December 5, 2010

Method Resolution Order
A
- 5.8 : D, B, A, C
- 5.10: D, B, C, A B C
D
mro
Sunday, December 5, 2010

Method Resolution Order
A
- 5.8 : D, B, A, C
- 5.10: D, B, C, A B C
- 5.12: Anything!
D
mro
Sunday, December 5, 2010

Method Resolution Order
A
- 5.8 : D, B, A, C
- 5.10: D, B, C, A B C
- 5.12: F
D
MRO::Define
Sunday, December 5, 2010

use strict;
use warnings;
package Booster::Gold;
our $VERSION = ‘1.00’;
...
1;
Sunday, December 5, 2010

use 5.12.0;
use warnings;
package Booster::Gold 1.00;
...
1;
Sunday, December 5, 2010

use 5.14.0;
use warnings;
package Booster::Gold 1.00 {
...
}
1;
Sunday, December 5, 2010

http://www.perl.org/get.html
Sunday, December 5, 2010

Any questions?
Sunday, December 5, 2010