1. The Evolution of Perl:
Highlights of Perl 5.14 and what's
new in the Perl world

2. Agenda
• Perl, ActivePerl, and ActiveState
• Version support – from the community and ActiveState
• What's new in Perl 5.14
• Re-factoring or maintaining existing code
• Web frameworks and Plack/PSGI
• Running Perl applications in the cloud

3. Perl
• Created by Larry Wall in 1987
• Perl 5 released in 1995
– language syntax stabilizes
– first “extensible” version (use Some::Module)
• Continued improvements through the 5.x series
• Perl 6 – beyond the scope of this presentation
– essentially a new language
– a language specification, not an official compiler
– Rakudo and other compilers available for early adopters

4. ActivePerl
• ActiveState contracted by Microsoft to improve Perl
performance and features for Windows
• ActivePerl enhancements submitted back to core Perl
• ActivePerl helps popularize Perl
– 2 million downloads per year
• adds some useful things
– PPM (Perl Package Manager)
– PerlCritic (from Perl Dev Kit)
– PerlScript and Perl for ISAPI extensions

5. & PPM
• CPAN is a 'one stop shop' for user-created modules
– standard toolchain for building, testing, and installing modules
– searchable
– standardized documentation format
– bug tracking
– HUGE: 23,000 modules (distributions)
• PPM is ActivePerl's client for installing these modules
– command line and GUI interface
– pre-compiled packages for specific platforms and Perl versions
– dependencies handled automatically
– provides most modules on CPAN (around 13,000 packages per
platform)

6. Perl Releases
• Perl releases used to be feature-based until 5.10
– released “when it's done”
• time-based releases since Perl 5.12 (April 2010)
– no feature milestones to define the release
– only features ready by release-time will be included
– predictable upgrade schedule

7. Perl Support Policy
• Perl community supports the most recent two releases
– new features
– security patches
– bug fixes
• ActiveState mirrors this policy for Community Edition
• Older versions available through Business Edition,
Enterprise Edition and OEM
– extended support
– professional services

8. What's new in Perl 5.14
•
Unicode improvements
•
Reliable exception handling
•
Non-destructive substitution
•
more...

9. Unicode
• Unicode 6.0 almost fully supported
• N{NAME} and charnames enhancements
• use feature 'unicode_strings'

10. Regular Expressions
• New character set modifiers:
– /a ASCII
– /d Default (or dodgy)
– /l Locale
– /u Unicode
• Caution: Modified stringification!
for example: qr/foo/i
– Old: (?i-xsm:foo)
– New: (?^i:foo)

11. Non-destructive substitution
(my $copy = $orig) =~ s/cat/dog/;
my $copy = $orig =~ s/cat/dog/r;
my @copy = map {
(my $copy = $_) =~ s/cat/dog/; $copy
} @orig;
my @copy = map { s/cat/dog/r } @orig;

12. Exception Handling
• Problems:
– eval() in DESTROY methods
– die() in DESTROY methods
– local $@
• Solution:
– Set $@ as late as possible before exiting the eval scope
• Exceptions are now a lot more reliable

13. Don’t use smart-match
• Smart match operator ~~ introduced in 5.10.0
• “Fixed” in 5.10.1 because is wasn’t working
• Still considered “too smart for it’s own good”
• Over 20 rules on how it works
• Rules apply recursively for container types
• May be replaced by “dump match” in the future
• All this applies to the given/when statements too.

14. Maintaining or updating Perl code
Try running it with with a newer interpreter – it may just work.
The interpreter will warn about deprecated code
– incremental approach: 5.8 to 5.10 to 5.12 to 5.14
• use warnings;
• less likely to “break” existing code
• setting up each environment takes time and effort
– direct approach: upgrading directly to 5.14
• address all the incompatibilities at once
• opportunity to re-factor and use new language features
• great excuse to write automated tests!
– write tests for the old version first, then run them against 5.12

15. Consult perldelta
• each Perl release has a list of differences and
incompatibilities with the previous version
– http://perldoc.perl.org/index-history.html
– also in the ActivePerl documentation
• pay particular attention to the Incompatible Changes
section
• don't skip a major version
– the perldeltas are not cumulative - going from 5.10 to 5.14,
check the 5.12 delta
– you can skip odd numbered development releases (5.9, 5.11,
etc.)

16. Check all modules
• binary modules are NOT compatible between major
Perl versions (e.g. 5.12 to 5.14)
• update to the latest modules where possible
• using PPM helps (ppm profile ...)
• Check the module's Changes file and documentation

17. Use Perl::Critic
• Perl::Critic – for examining your source code
– uses Conway's “Perl Best Practices”
– points out bad or deprecated code and suggests alternatives
• ActivePerl has a helpful GUI interface
– added in 5.12
– formerly part of the Perl Dev Kit

18. ... or don't upgrade
• You may choose not to upgrade to 5.12 or 5.14 – there
are commercial support options:
• ActivePerl Business Edition provides access to older
builds of ActivePerl
• ActivePerl Enterprise Edition can provide access and
support for specific versions and platform builds
• OEM licensing lets you distribute ActivePerl with your
product

19. Web Frameworks and Plack/PSGI
•
Catalyst
•
Mojolicious
•
Dancer
... all work with Plack/PSGI
•
interface between Perl web applications and web servers
•
simplifies web application deployment

20. Catalyst
•
most popular framework in a recent ActiveState survey
– relatively speaking, it's been around a long time (2005)
– wide enterprise adoption
•
a “heavyweight” framework
– many dependencies
– very “TMTOWTDO” design, lots of choices for sub-
components
– very flexible

21. Mojolicious
•
new web framework from author of Catalyst, Sebastian
Riedel
•
Mojo originally intended as a rewrite of Catalyst
internals
•
lighter weight
– fewer dependencies
– “optimized for user-friendliness”

22. Dancer
•
micro-framework
•
for smaller sites, web services, or people who just
prefer a very lightweight framework
•
similar to Ruby's Sinatra or Python's Flask

23. Perl in the cloud
The Platform as a Service approach proved very popular in the Ruby on
Rails community – has also caught on with other languages and
frameworks
• a framework for frameworks...
– not a PaaS... it's for creating your own PaaS
– supports multiple languages and frameworks
– Perl web apps via PSGI
– based on Cloud Foundry – more accessible for Perl and Python developers
– http://activestate.com/cloud

24. Thank You
Speak to a representative about
ActivePerl Business Edition, Enterprise Edition
or OEM: 1-866-510-2914
business-solutions@activestate.com
www.activestate.com
08/12/10