title:HTML::Template notes and hints
description:Examples of Perl and HTML for using the HTML::Template Perl module
keywords:template,html,how,to,howto,mini

Some of these examples use code snippets copied directly from other
authors. Many thanks to those authors. I've extended their work here
to fill in questions they did not address, and which I found confusing
at the time.

HTML::Template is pretty simple.  There are three basic tags:

----------- Variables -------------
<!-- TMPL_VAR NAME=FOO -->  : Simple variable substitution.
Ex (html).
	<p>Hello and welcome to my site <b><!-- TMPL_VAR NAME=USER
--></b>!</p>
Ex (perl).
	my %tmpl_hash;
	$tmpl_hash{ 'USER' } = 'Timmy';
	$template->param( \%tmpl_hash );


----------- If-then-elses -------------
<!-- TMPL_IF NAME=BAR --><!-- TMPL_ELSE --><!-- /TMPL_IF --> : Governs
what will and will not appear on a page.
Ex. (html):
	<p>
    	   There will
	   <!-- TMPL_IF NAME=IS_RAGNAROK -->not<!-- /TMPL_IF -->
	   be a tomorrow.
        </p>
Ex. (perl):
	%tmpl_hash;
	$tmpl_hash{ 'IS_RAGANROK' } = 1;
	$template->param( \%tmpl_hash );
N.B.  If the TMPL_IF variable is not set, it is assumed to be false.
Also, there is no ELSE_IF, so you may have to nest TMPL_IF tags.

----------- Loops -------------
<!-- TMPL_LOOP NAME=BAZ --><!-- /TMPL_LOOP --> : Used for repeating data
Ex. (html)
	<p>I am afraid of: <br>
	 <!-- TMPL_LOOP NAME=PHOBIAS -->
	   <!-- TMPL_VAR NAME=FEAR --><br>
	 <!-- /TMPL_LOOP -->
	</p>
Ex. (perl)
	my %tmpl_hash;
	my @phobias;
	my %phobia_hash_1;
	$phobia_hash_1{ 'FEAR' } = 'pirates';
	push(@phobias, \%phobia_hash_1);
	my %phobia_hash_2;
	$phobia_hash_2{ 'FEAR' } = 'jellybeans';
	push(@phobias, \%phobia_hash_2);
	$tmpl_hash{ 'PHOBIAS' } = \@phobias;
	$template->param( \%tmpl_hash );


TMPL_IFs can go in TMPL_LOOPs, and vice-versa.  TMPL_LOOPs can go inside
other TMPL_LOOPs.  TMPL_IFs can go inside other TMPL IFs. TMPL_VARs can go
wherever they damn well please.

It's not hard.  It's just a hash-o-rama in the perl.


#!/usr/bin/perl -w
use HTML::Template;

# open the html template
my $template = HTML::Template->new(filename => 'test.tmpl');

# fill in some parameters
$template->param(HOME => $ENV{HOME});
$template->param(PATH => $ENV{PATH});

# send the obligatory Content-Type and print the template output
print "Content-Type: text/html\n\n", $template->output;