1.2. The Templating Ecosystem

At least half a dozen mature and respected templating systems are available for Perl. The best-known and best-supported template processors include the following:

Text::Template

Text::Template is a library for generating form letters, building HTML pages, or filling in templates generally. A template is a piece of text that has little Perl programs embedded in it here and there. When you fill in a template, you evaluate the little programs and replace them with their values. These programs are written in Perl: you embed Perl code in your template, with { at the beginning and } at the end. If you want a variable interpolated, you write it the way you would in Perl. If you need to make a loop, you can use any of the Perl loop constructions. All the Perl built-in functions are available.

Text::Template is available from http://www.plover.com/~mjd/perl/Template/ or from CPAN (http://search.cpan.org/dist/Text-Template/).

HTML::Template

HTML::Template attempts to make using HTML templates easy and natural. It extends standard HTML with a few HTML-like tags, and enforces the divide between design and programming by restricting what a template is capable of doing. By limiting the programmer to using just simple variables and loops in the HTML, the template remains accessible to designers and other non-Perl people. The use of HTML-like syntax goes further to make the format understandable to others.

HTML::Template is available from CPAN (http://search.cpan.org/dist/HTML-Template/).

HTML::Mason

HTML::Mason is a Perl-based web site development and delivery system. Mason allows web pages and sites to be constructed from shared, reusable building blocks called components. Components contain a mix of Perl and HTML, and can call each other and pass values back and forth like subroutines. Components increase modularity and eliminate repetitive work: common design elements (headers, footers, menus, logos) can be extracted into their own components where they need be changed only once to affect the whole site. Mason also includes powerful filtering and templating facilities and an HTML/data caching model.

HTML::Mason is available from http://www.masonhq.com/ and CPAN (http://search.cpan.org/dist/HTML-Mason/).

HTML::Embperl

Embperl gives you the power to embed Perl code in your HTML documents, and the ability to build your web site out of small reusable objects in an object-oriented style. You can also take advantage of all the usual Perl modules (including DBI for database access), use their functionality, and easily include their output in your web pages.

Embperl has several features that are especially useful for creating HTML, including dynamic tables, form field processing, URL escaping/unescaping, session handling, and more.

Embperl is a server-side tool, which means that it's browser-independent. It can run in various ways: under mod_perl, as a CGI script, or offline.

HTML::Embperl is available from http://www.ecos.de/ or CPAN (http://search.cpan.org/dist/HTML-Embperl/).

Apache::ASP

Apache::ASP provides an Active Server Pages port to the Apache web server with Perl scripting only, and enables development of dynamic web applications with session management and embedded Perl code. Apache::ASP also provides many powerful extensions, including XML taglibs, XSLT rendering, and new events not originally part of the ASP API.

Apache::ASP is available from CPAN (http://search.cpan.org/dist/Apache-ASP/).