Mason 2.0 is an update to the Mason templating system for Perl that generates dynamic web content. Some key changes in Mason 2.0 include using Moose to define components as classes rather than instances, integrating with PSGI for web serving rather than relying on mod_perl, and standardizing file extensions. The update aims to modernize Mason and address longstanding issues while retaining the ability to write Perl code directly in templates.

1. Mason 2
True OO templating for Perl
Jonathan Swartz
July 26, 2011
Seattle Perl Users Group

2. What is Mason?
Templating system for generating dynamic content
(e.g. web pages)
<& header.mi &>
<ul>
% foreach my $article (@articles) {
<li>
<a href="<% $article->url %>">
<% $article->title %>
</a>
</li>
%}
</ul>
<& footer.mi &>

3. Mason Timeline
• 1998 - HTML::Mason 0.01
• 2001 - HTML::Mason 1.0
• 2002 - HTML::Mason 1.1, O’Reilly book
• - Used by many mod_perl sites
• 2006 - Amazon switches to Mason
• - The lost years
• 2011 - Mason 2.0

4. History: Past 5 years
• Mason enters stasis mode
• MVC supplants embedded-code
• Web frameworks emerge
• Catalyst+TT becomes Perl web “standard”
• Mason wiki and mail list fills with weeds
• Figured I was done... then they drag me back

5. Why Mason 2?
• New technologies
• Moose
• Plack/PSGI
• Long-desired syntax and features
• Long-standing annoyances
• Changes in how people use Mason today

6. Mason 1 vs 2
It’s called... HTML::Mason Mason
Components are... Instances of a class Classes (Moose)
Web integration
via... mod_perl + glue PSGI
Standardized,
Filenames are... Arbitrary, unenforced
semi-enforced
Plugins are... Limited set of hooks Moose roles

7. Components as Moose Classes
arguments --> attributes
autohandlers --> parent classes
“inheritance” --> inheritance
subcomponents --> methods
common package --> distinct package
anon subroutines --> named subroutines
Plus the power of Moose
(roles, method modifiers, ...)

8. PSGI/Plack
• PSGI - Interface spec between Perl web
apps and servers (like CGI)
• Allows Mason to work from mod_perl,
Perl-only server, standalone script...
• Plack - Common tools, middleware, servers
(debug console, error trace, sessions...)

9. Catalyst/TT vs Mason
Separate M
Separate M, V, and C
Unified V and C
Simplified template
Perl in templates
language
Designer friendly Programmer friendly

10. Standard file extensions
• .mc - top-level component
• .mi - internal component
• .mp - pure-perl component

11. Demo

12. More information
• http://search.cpan.org/perldoc?Mason
• http://www.openswartz.com/