Modern Perl

Fifteen years of Perl development

In twenty minutes

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/

We all hate SQL

DBIx::Class

Builds on DBI

DBIx::Class::Schema::Loader

$ dbicdump MyClass 'dbi:mysql:<db>;<hostname>' <user> <password> Dumping manual schema for MyClass to directory . ... Schema dump completed.

Class for each table
Attribute for each column
Type, 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, “ ”; }

while (<FILE>) { my ($code, $name, $desc) = split; my $new_obj = $objs->create({ code => $code, name => $name, desc => $desc, }); print 'New object id: ', $new_obj->id, “ ”; }

Complex searching
Prefetching data
Many-to-many relationships
Database migrations
Replicated databases

http://dbix-class.org/

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 features
Lazy build
Delegation
Defaults
Triggers
Roles/Traits
Like mixins or interfaces

MooseX::*

MooSex::*

MooseX::*

http://moose.perl.org/

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_address] @davorg @perlfoundation

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Modern Perl

by Dave Cross on Sep 12, 2010

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