Perl 5.12 for Everyday Use

Perl 5.12for everyday use

Sunday, December 5, 2010

perl5100delta

5.12 isn’t like 5.10

perl5100delta

- after 5.8, we had to wait 5 years for 5.10

perl5100delta

- after 5.8, we had to wait 5 years for 5.10

- 5.12 came out 2 years after 5.10

perl5100delta

5.12 is a Nice Change

perl5100delta

- 5.10 was a huge set of changes

perl5100delta

- 5.12 is a lot smaller

perl5100delta

- 5.12 is not as compelling as 5.10

perl5100delta

- 5.12 is not as compelling as 5.10

- and that’s a good thing

perl5100delta

5.12 is a Mixed Bag

perl5100delta

5.12 is a Mixed Bag

- this talk isn’t just for beginners

perl5100delta

5.12 is a Mixed Bag

- some of these changes are at the edges

perl5100delta

5.12 is a Mixed Bag

- but they’re all practical

perl5100delta

5.12 is a Mixed Bag

- but they’re all practical

- except for the ones that aren’t

perl5132delta

By the way, 5.14...

perl5132delta

By the way, 5.14...

- is going to be awesome

perl5132delta

By the way, 5.14...

- and available in about nine months

perl5132delta

By the way, 5.14...

- and available in about nine months

- and it’s going to be awesome

perl5101delta

...and 5.10 is frozen.

perl5101delta

- 5.10 is the last release of the old way

perl5101delta

- that means it got some features backported

perl5101delta

- that will never happen again

perl5101delta

- that will never happen again

- I’ll point out 5.12isms that got into 5.10.1

but enough about other versions

let’s talk about 5.12

feature

First: A Warning

feature

First: A Warning

- 5.12 is backwards compatible

feature

First: A Warning

- but adds new keywords and operators

feature

First: A Warning

- they’re not enabled by default

feature

First: A Warning

- use feature ‘mtfnpy’;

feature

First: A Warning

- use 5.012;

feature

First: A Warning

- use 5.012;

- read the perldoc

feature

First: A Warning

- use 5.012;

- read the perldoc I’m a perldoc ref!

feature

First: A Warning

- use 5.012;

- read the perldoc

perlsyn

- the smart match operator changed

$old ~~ $new

also in 5.10.1

perldoc

- 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

autodie

also in 5.10.1

autodie

- like Fatal

also in 5.10.1

autodie

- like Fatal

- but deadlier

also in 5.10.1

autodie

open my $fh, ‘>‘, $filename;

while (<$fh>) { ...}

close $fh;

autodie

open my $fh, ‘>‘, $filename or die “couldn’t open $filename: $!”;

while (<$fh>) { ...}

close $fh or die “couldn’t close $filename: $!”;

autodie

use autodie;

open my $fh, ‘<‘, $filename;

while (<$fh>) { ...}

close $fh;

autodie

use autodie;

open my $fh, ‘>‘, $filename;

while (<$fh>) { no autodie; rmdir or warn “couldn’t remove $_: $!”;}

close $fh;

perldoc

autodie problems

- autodie doesn’t affect print

- you must close filehandles explicitly

Unicode

perlunicode

Perl is Good at Unicode

perlunicode

Perl 5.12 is Better

perlunicode

Perl 5.12 is Better

- Unicode 5.2

perlunicode

Perl 5.12 is Better

- Unicode 5.2

- every character property is available

perlunicode

Perl 5.12 is Better

- Unicode 5.2

- every character property is available

- \X in regex is more sensible

perlunicode

“The Unicode Bug”

perlunicode

- strings aren’t always treated as Unicode

perlunicode

- this causes weird bugs that take ages to find

perlunicode

- this causes weird bugs that take ages to find

- use feature ‘unicode_strings’;

perldoc

use feature ‘unicode_strings’;

perldoc

use 5.12.0;

perldoc

use 5.10.0;

perldoc

use 5.10.0;

use feature qw( say state switch);

perldoc

use 5.12.0;

perldoc

use 5.12.0;

use feature qw( say state switch unicode_strings);

perldoc

use 5.12.0;

use feature qw( say state switch unicode_strings);

use strict;

Container Improvements

my %hash = (a => 1, b => 2);

while (my ($k, $v) = each %hash) { say “value for $k is $v”;}

my %hash = (a => 1, b => 2);

while (my ($k, $v) = each %hash) { say “value for $k is $v”;}

value for a is 1value for b is 2

my @array = qw(a b);

value for 0 is bvalue for 1 is a

for my $k (0 .. $#array) { say “value for $k is $array[$k]”;}

while (my ($k, $v) = each @array) { say “value for $k is $v”;}

for my $k (0 .. $#array) { say “value for $k is $array[$k]”;}

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);}

while (my ($k, $v) = each @array) { say “value for $k is $v”; do_something(\@array);}

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; }}

AVOIDeach @array

local ??

use Ancient::Utility qw(stuff);

my $result = do { local $Ancient::Utility::WIDTH = 10; stuff( $input );};

my $href = { a => 1, b => 2 };

my $result = do { local $href->{a} = 3; stuff( $href );};

my $href = { a => 1, b => 2 };

my $result = do { delete local $href->{a}; stuff( $href );};

perlvar

$[ - first index of array

perlvar

- so you can make $array[1] mean first

perlvar

- isn’t that awesome???

perlvar

- isn’t that awesome???

- yeah, about as awesome as Comic Sans

perlvar

$[ = 1;

for (1 .. $#array) { ...}

perlvar

for ($[ .. $#array) { ...}

perlvar

Assigned to $[. Are you some kind of idiot or something? at -e line 123.

perlvar

Use of assignment to $[ is deprecated at -e line 123.

More About Deprecations

perlvar

@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

@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

@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

now we can remove stuff from the core distribution

Class::ISAPod::PlainerShell

Class::ISAPod::PlainerShellSwitch

… and …

my $x = get_input;

if ( $x >= 0 ) {

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;} else {

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;} else { ...

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;} else { ...}

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;} else { ...}

my $x = get_input;

if ( $x >= 0 ) { do_something for 0 .. $x;} else { die “Unimplemented”}

sub virtual_method { ... }

sub method_I_will_write_later { ... }

Unimplemented at Some::Library line 123

AVOID...

(except maybe in slides and pseudocode)

sub virtual_method { confess ‘...’}

sub method_I_will_write_later { confess ‘...’}

error message improvements

perldiagSunday, December 5, 2010

perldiag

perl -MCGI -e’my $q = CGI->new;’Unrecognized character \xE2 in column 12 at -e line 1.

perldiag

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.

perl -MCGI -e’my $q = CGI->new;’Unrecognized character \xE2 in column 12 at -e line 1.

perldiag

My Favorite 5.10-ism?

Use of uninitialized value $time in concatenation (.) or string at hello.plx line 9.

$str = “Greetings, $name. Your last login was $last. It is now $time.”;

perldiag

if (length $input->{new_email}) { $user->update_email(...);}

perldiag

Use of uninitialized value in length at - line 3120.

perldiag

overloading

my $object = Object->new;

print $object;

my $object = Object->new;

{ no overloading; print $object;}

my $filename = get_filename;

if (-d $filename) { handle_directory($filename);}

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’; ...;};

my $file = get_file;

if (-d $file) { handle_directory($file);}

my $filename = get_file;

if (-d $file and -x _) { handle_directory($file);}

my $filename = get_filename;

if (-d -x $filename) { handle_directory($filename);}

AVOIDoverload -X

~$ perl5.10.0 -E ‘say scalar localtime 2**31-1’

~$ 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’

~$ perl5.10.0 -E ‘say scalar localtime 2**31’Fri Dec 13 15:45:52 1901

~$ perl5.12.0 -E ‘say scalar localtime 2**31-1’

~$ perl5.12.0 -E ‘say scalar localtime 2**31’

~$ perl5.12.0 -E ‘say scalar localtime 2**31’Mon Jan 18 22:14:08 2038

some non-everyday changes

Method Resolution Order

mroSunday, December 5, 2010

- 5.8 : D, B, A, C

- 5.10: D, B, C, A

- 5.8 : D, B, A, C

- 5.10: D, B, C, A

- 5.12: Anything!

- 5.8 : D, B, A, C

- 5.10: D, B, C, A

- 5.12: F

MRO::DefineSunday, December 5, 2010

use strict;use warnings;

package Booster::Gold;our $VERSION = ‘1.00’;

use 5.12.0;use warnings;

package Booster::Gold 1.00;

use 5.14.0;use warnings;

package Booster::Gold 1.00 { ...}

http://www.perl.org/get.html

Any questions?

Perl 5.12 for Everyday Use

Documents

README - IBM · 2016. 7. 1. · openldap openssh openssh-clients ... pcre pdksh perl perl-DateManip perl-Filter perl-HTML-Parser perl-HTML-Tagset perl-lib perl-URI pinfo popt portmap

Apostila de EWB 5.12

COMO ESCALAR 5.12

Billa 5.12.-14.12.2011

Learning Perl - Amazon S3 · 2019-02-26 · Perl Cookbook Perl Debugger Pocket Reference Perl in a Nutshell Perl Testing: A Developer’s Notebook Practical mod-perl Perl Books Resource

Opa - Aula 2 5.12

Dollar Saver Saratoga 5.12

Perl 5.10 и 5.12

The Perl Journal The Perl Journal

Фрагменты Perl 6 в Perl 5.10

Modern Perl for Non-Perl Programmers

Dollar Saver Amsterdam 5.12

Hard Hat News 5.12

Programming Perl - Perl Training · This is version 1.39 of Perl Training Australia’s "Programming Perl" training manual. Table of Contents 1. About Perl Training Australia

Perl::Critic and Perl::Tidy

Use Perl like Perl

Qnext Intro April.5.12

Perl Practical Extraction and Report Language. PERL language Windows Perl-Win32 ActiveState Perl Linux use the whereis command to locate Perl sources

2005. 5.12

Perl Switches with the perl command