Original HTML::Template is written by Sam Tregar, sam@tregar.com with contributions of many people
mentioned there. Their efforts caused HTML::Template to be mature html tempate engine which separate
perl code and html design. Yet powerful, HTML::Template is slow, especially if mod_perl isn't available
or in case of disk usage and memory limitations.
HTML::Template::Pro is a fast lightweight C/Perl+XS reimplementation of HTML::Template (as of 2.9) and
HTML::Template::Expr (as of 0.0.7). It is not intended to be a complete replacement, but to be a fast
implementation of HTML::Template if you don't need querying, the extended facility of HTML::Template.
Designed for heavy upload, resource limitations, abcence of mod_perl.
HTML::Template::Pro has complete support of filters and HTML::Template::Expr's tag EXPR="<expression>",
including user-defined functions and construction <TMPL_INCLUDE EXPR="...">.
HTML::Template work cycle uses 2 steps. First, it loads and parse template. Then it accepts param()
calls until you call output(). output() is its second phase where it produces a page from the parsed
tree of template, obtained in the 1st step.
HTML::Template::Pro loads, parse and outputs template on fly, when you call $tmpl->output(), in one pass.
The corresponding code is written in C and glued to Perl using Perl+XS. As a result, comparing to
HTML::Template in ordinary calls, it runs 10-25 times faster. Comparing to HTML::Template with all
caching enabled under mod_perl, it still 1-3 times faster. At that HTML::Template caching requires
considerable amount of memory (per process, shareable, or on disk) to be permanently filled with parsed
trees, whereas HTML::Template::Pro don't consumes memory for caches and use mmap() for reading templates
on disk.
Introduction to HTML::Template and syntax of template files is described in HTML::Template::SYNTAX. Perl
interface of HTML::Template and HTML::Template::Pro is described in HTML::Template::PerlInterface.