untitled

250 10 Transforming with Traditional Programming Languages

use Template;

while (<>) {

chomp;

split(/:/);

$name = $_[0];

$content = $_[1];

}

$tt = new Template;

$vars = {

name => $name,

content => $content,

};

$tt->process(’part.tt’, $vars);

Program 10.21 Using Perl templates

Now consider a more interesting transformation task: the first task of this

chapter. To use a Perl template, the data extracted from the input file must

be organized into a data structure to be used by the template processor for

instantiating the template as in program 10.22. Thewhilestatement con-

structs an array of hashes. Each hash gives the information about one inter-

view of the health study. In other words, each hash represents one record of

the health study database. The template processor is given this array in the

same way as in the earlier program, except that now there is just one hash

key:HealthStudyInterviews. This will be the name of the array within

the template. The template is shown in template 10.2. Notice that one iter-

ates over the elements of the array in almost the same way as in Perl. The

Template Toolkit, however, uses a more simplified notation than Perl:

1. Variables usually have no initial character such as%[email protected]
   Toolkit does use the$but only when one is substituting a value in an
   expression. For example, if one has a variable namedstatuswhose
   value is “obese,” then the expressioni.statuswould have two different
   meanings. Should it mean$i{status}or should it mean$i{obese}?
   In the Template Toolkit one specifies the second one by writingi.$sta-
   tus. The $ prefix in the Template Toolkit means “substitute the value of
   the variable here.”