4.3. Embedded Perl Scripting

As systems built by embedding scripts within HTML are
typically easier to customise than systems build by
generating HTML from scripts, embedded scripting is now
a well established web-publishing solution.

Likewise, Perl embedded in SDF can be a powerful
combination providing this same flexibility with some
additional benefits:
SDF is arguably easier to read than HTML
the information can be published in several formats.

To embed a block of Perl code, the script filter is
used.

For example:

    !block script
    for $i ('a' .. 'z') {
        print "$i";
    }
    !endblock

To embed an expression within paragraph text,
the [[..]] syntax is used.

For example:

  Hello [["wor" . "ld"]]

Note: If the expression is a single word, it is assumed
to be a variable name, otherwise the expression is
treated as a Perl expression.

For single line scripts, the script macro can be used.

For example:

  !script $next_version = $var{'VERSION'} + 1