modern perl

Modern
Perl

Fifteen years
of Perl
development

In
twenty
minutes

1995

Everyone
uses Perl to build dynamic web sites

Nasty
CGI
scripts

Web technology
has moved on
since then

Perl technology
has moved on
since then

Perceptions
of Perl
are stuck in
the mid 90s

Hi!
We're the
Perl community
and we suck at
marketing

Perl has all
the facilities
you would expect
in a modern
dynamic language

Fully!
Buzzword!
Compliant!

A note on
version numbers

Perl 5
is the current
version of Perl

Specifically
5.12.1

Specifically
5.12.

Specifically
5.12.2

Perl 6
is still in
development

(If you want
to know more about Perl 6
then ask me later)

Perl 5
is still thriving

Some powerful
Perl tools

Template
Toolkit

Templating
engine

Powerful and
flexible

Web and
non-web

Separation
of concerns

Dear [% name %],

You owe me [% debt %].

Please pay up by [% date %] or I'll send the boys round.

Love

Dave...

#!/usr/bin/perl

use Template;

my $tt = Template->new;
my $data = {
name => 'Joe Random',
debt => 100,
date => '18 September',
};

$tt->process('template.tt', $data);

Use with objects

[% FOREACH debt IN debts %]
Dear [% debt.name %],

You owe me [% debt.amount %].

Please pay up by [% debt.date %] or I'll send the boys round.

Love

Dave...
[% END %]

#!/usr/bin/perl

use Template;
use Debt;

my $tt = Template->new;

my @debts = Debt->find_all;
$tt->process('template.tt',
{ debts => \@debts});

http://tt2.org/

ORM

We all
hate SQL

DBIx::Class

Builds on DBI

DBIx::Class::Schema::Loader

$ dbicdump MyClass 'dbi:mysql:;'
Dumping manual schema for MyClass to directory . ...
Schema dump completed.

Class for each table

Attribute for each columnType, mandatory/optional, auto-increment

Data type inflation

Relationships

#!/usr/bin/perl

use MyClass;

my $sch = MyClass->connect('...');

my $objs = $sch->resultset('MyTable');

while ($objs->next) {
print $_->name, \n;
}

while () {
my ($code, $name, $desc) = split;

my $new_obj = $objs->create({
code => $code,
name => $name,
desc => $desc,
});

print 'New object id: ', $new_obj->id, \n;
}

Complex searching

Prefetching data

Many-to-many relationships

Database migrations

Replicated databases

http://dbix-class.org/

Moose

The Modern
Object System
for Perl 5

Perl 5's standard
OO system
looks a bit
bolted on

(That's
because
it was
bolted on)

Moose hides
all that
nastiness

Pretty
syntactic
sugar

Declarative
syntax for
attributes

package Debt;

use Moose;

has name => (isa => 'Str', is => 'rw', required => 1);
has amount => (isa => 'Num', is => 'rw', required => 1);
has date => (isa => 'DateTime', is => 'rw');

#!/usr/bin/perl

use 5.010;
use strict;
use warnings;

use Debt;

my $debt = Debt->new({
name => 'Joe Random',
amount => 100,
});

say $debt->name, ' owes ', $debt->amount;

# Add interest
$debt->amount($debt->amount * 1.1);
say $debt->name, ' owes ', $debt->amount;

use DateTime;

# Set due date
$debt->date(DateTime->now->add(days => 28));
say $debt->date;

# Easier to read
say $debt->date->strftime('%A %d %B %Y');

More attribute featuresLazy build

Delegation

Defaults

Triggers

Roles/TraitsLike mixins or interfaces

MooseX::*

MooSex::*

MooseX::*

http://moose.perl.org/

MVC

Catalyst

Builds on
existing tools

Model is
DBIx::Class

View is
Template Toolkit

(These are
just defaults)

Easy to get application framework running

$ catalyst.pl MyApp
created "MyApp"
created "MyApp/script"
created "MyApp/lib"
created "MyApp/root"
created "MyApp/root/static"
created "MyApp/root/static/images"
created "MyApp/t"

[ ... ]

created "MyApp/Makefile.PL"
created "MyApp/script/myapp_cgi.pl"
created "MyApp/script/myapp_fastcgi.pl"
created "MyApp/script/myapp_server.pl"
created "MyApp/script/myapp_test.pl"
created "MyApp/script/myapp_create.pl"
Change to application directory and Run "perl Makefile.PL" to make sure your install is complete

$ cd MyApp
$ script/myapp_server.pl
[debug] Debug messages enabled
[debug] Statistics enabled
[debug] Loaded plugins:
.----------------------------------------------------------------------------.
| Catalyst::Plugin::ConfigLoader 0.27 |
'----------------------------------------------------------------------------'

[ ... lots of information ... ]

[info] MyApp powered by Catalyst 5.80023
You can connect to your server at http://localhost:3000

Plugins to handle common
requirements

Authentication/Authorisation

Session handling

CatalystX::*

Catalyst::Plugin::AUTOCRUD

http://catalystframework.org/

PSGI / Plack

PSGI is a
specification

Like a
super-charged
CGI

And a lot like
WSGI

Plack is a
reference
implementation

And a lot like
Rack

Make it easy to move web apps

Different application technologies

Different
web hosting technologies

Take a PSGI application and run it anywhere

PSGI app is a subroutine reference

# app.psgi
my $app = sub {

# clever stuff goes here

};

Input comes from a hash passed to sub

# app.psgi
my $app = sub {

my $env = shift;

# clever stuff goes here

};

Sub returns a reference to
an array

# app.psgi
my $app = sub {

my $env = shift;

return [
200,
[ 'Content-type', 'text/plain' ],
[ 'Hello world' ],
];
};

Plack distribution includes
many tools

plackup -
a simple PSGI web server

$ plackup app.psgi
HTTP::Server::PSGI Accepting connections at http://localhost:5000/

Plack::Request
Plack::Response

use Plack::Request;
use Plack::Response;

use Data::Dumper;
my $app = sub {
my $req = Plack::Request->new(shift);
my $res = Plack::Response->new(200);
$res->content_type('text/plain');
$res->body(Dumper $req);
return $res->finalize;
}

Plack::Middleware::*
Plack::App::*

Most Perl web frameworks support Plack

http://plackperl.org/

Other
Modern Perl
tools

DateTime

TryCatch
& autodie

Test::*
& TAP::*

A lot has happened in the ten years you've been ignoring Perl

Your local
Perl Mongers
will be happy
to tell you more

http://london.pm.org/
http://pm.org/

Dave Cross
[email protected]
@davorg
@perlfoundation

modern perl

Technology