Perl isn’t just for greybeards and sysadmins - it’s a vibrant, modern language that’s used for websites ranging from Craigslist to the BBC iPlayer. Learn what’s new in the Perl language, hear about some popular web frameworks used by Perl developers, and learn how to build a simple web app in the Dancer framework.

1. Modern Web
Development in Perl
Jason A. Crome
https://crome-plated.com
March 14, 2017 Copyright (C) 2017, Jason A. Crome

2. What is Perl?

3. Common Misconceptions
• It’s dead
• It’s dying
• It’s just for sysadmins
• It’s not for real development
• It’s not modern - hasn’t been updated in years

4. Why the Misconceptions?
• Bad Marketing
• Perl 6
• Matt’s Script Archive

5. Perl 6
• Sister language to Perl 5, not a successor!
• Poorly marketed as such
• Fantastic language!
• Both functional and procedural
• Thread-safe

6. Strengths
• Data Munging
• Bioinformatics
• Devops
• Web application development
• MMOs
• Whipuptitude

7. Weaknesses
• Threading
• Device Drivers
• 3D game development
• Learning curve

8. Who’s Using Perl?
• ZipRecruiter
• Booking.com
• Craigslist
• Ticketmaster
• Amazon
• BBC
• NASA
• Rent.com
• DuckDuckGo
• IMDB
• CrowdTilt
• ShutterStock
• ServerCentral
• Bank of America

10. Actively Developed
• 24th version of Perl 5
• 26th version to be released ~June
• One major release every year
• 5.26 will be 8th production release in last 7 years
• Does that seem like a dead language to you?!

11. What is Modern Perl?
• First-class OO programming
• Great Testing Infrastructure
• Deployment and Configuration Toolchain
• Active user community
• Modern language features
• Modern frameworks

12. Object Oriented
• Moose
• Moo
• (before that) Overloaded hashes

13. package Point;
use Moose;
has 'x' => (isa => 'Int', is => 'rw', required => 1);
has 'y' => (isa => 'Int', is => 'rw', required => 1);
sub clear {
my $self = shift;
$self->x(0);
$self->y(0);
}
package Point3D;
use Moose;
extends 'Point';
has 'z' => (isa => 'Int', is => 'rw', required => 1);
after 'clear' => sub {
my $self = shift;
$self->z(0);
};

14. # hash or hashrefs are ok for the constructor
my $point1 = Point->new(x => 5, y => 7);
my $point2 = Point->new({x => 5, y => 7});
my $point3d = Point3D->new(x => 5, y => 42, z => -5);
Using the Point Class

15. Roles with Moose
package MyApp::CLI::SetPassword;
use strictures 2;
use MooseX::App::Command;
extends qw( MyApp::CLI );
with qw(
MyApp::Role::CLI::WithPassword
MyApp::Role::CLI::WithUsername
MyApp::Role::CLI::WithUser
);
use MyApp::Module;
sub run ( $self ) {
$self->_say( "Changing password for " . $self->username . '...' );
$self->user->password( $self->password );
$self->user->update;
say "Done!";
}
1;

16. Testing Infrastructure
• Test2
• Test::Class::Moose
• prove
• Test::Harness
• TAP

17. Deployment/Configuration
• Plack
• cpanfile
• Carton
• perlbrew
• plenv

18. Community
• Perl’s greatest strength
• Perl Mongers
• YAPC / TPC
• (Meta)CPAN

19. MetaCPAN

20. Modern Language Features/
Tools
• Named Parameters
• XS
• POD
• Perlcritic
• Perltidy

21. Named Parameters
sub clear( $self ) {
$self->x(0);
$self->y(0);
}
after 'clear' => sub( $self ) {
$self->z(0);
};
sub set( $self, $x, $y, $z) {
$self->x( $x );
$self->y( $y );
$self->z( $z );
}

22. Modern Frameworks
• ORMs
• Templating Frameworks
• Web App Frameworks

23. ORMs
• DBI
• Class::DBI
• DBIx::Class
• Rose::DB

24. DBIx::Class
$user = $schema->resultset('User')->find( { email => $self->email } );
$user = $schema->resultset('User')->create(
{ username => $self->username,
password => $self->password,
email => $self->email,
}
);
my $user_rs = $schema->resultset('User')->search({
email => { like => '%example.com' },
},{
order_by => { username => 'ASC' },
}
);

25. Templating Frameworks
• HTML::Template
• Mason
• Template Toolkit
• And many, many others…

26. Web App Frameworks

27. And now, Dancer2!

28. Questions?

29. Thanks!
https://crome-plated.com
jason@crome-plated.com
Sample Code: https://github.com/cromedome/RWD
Slides: https://www.slideshare.net/cromedome/modern-web-
development-in-perl

30. Bonus 1: Point Class,
Old World Perl

31. package Point;
sub new {
my ($class, $x, $y) = @_;
my $self = {
x => $x,
y => $y,
};
return bless $self, $class;
}
sub get_x {
return $_[0]->{x};
}
sub set_x {
return $_[0]->{x} = $_[1];
}
sub get_y {
return $_[0]->{y};
}
sub set_y {
return $_[0]->{y} = $_[1];
}
1;