As mentioned above, you can always use both multi-array and single-array format, even if you chose the other as your default one. This is provided by the datasource parameter available in each section. If you work in OPT_SECTION_MULTI mode and you want to read subsection data from the upper section table, you specify here its block that contains the data:

<td>Product categories</td> {* for OPT_SECTION_MULTI *}
</tr>
{section=products}
<tr>
<td>{$products.name}</td>
<td><ul>
  {* read the data like in OPT_SECTION_SINGLE *}
  {section=categories; !x; !x; $products.categories}
  <li>{$categories.name} (or) {$products.categories.name}</li>
  {/section}
</ul></td>
</tr>
{/section}
</table>

The data of categories subsection are located in $products.categories block.

<td>Product categories</td> {* for OPT_SECTION_SINGLE *}
</tr>
{section=products}
<tr>
<td>{$products.name}</td>
<td><ul>
  {* read the data like in OPT_SECTION_MULTI *}
  {section=categories; !x; !x; $categories}
  <li>{$categories.name} (or) {$products.categories.name}</li>
  {/section}
</ul></td>
</tr>
{/section}
</table>

OPT 1.1.0 introduces the new way of handling the section data. Instead of passing the already-generated lists to the parser, we pass only the function/method that will generate it, if a section with a specified name is used. This can be useful in modular websites - if a template does not make use of some available sections, the data for them are not generated. This is, what we call dynamic sections.

The template designer does not know anything, which section is dynamic and which is not - this is only a PHP script issue. OPT supports two ways of processing dynamic sections: statically compiled (default) and runtime.

In order to make dynamic section, we have to write a function or class method that generates the section data in the format described above. We pass a standard PHP callback to the parser with optClass::assignDynamic() method.

If the dynamic sections are statically compiled, the callbacks must be defined BEFORE the template compilation. The calls of the functions are compiled in the template and we must not change it later (in other words - you must not pass callback for one request and the normal data for the second using the same section and template). The advantage is that "normal" sections are not touched by the compiler and work like in previous releases of OPT.

The dynamic sections may be also handled during the runtime. Now you can use function callback, wherever and whenever you want, but at the cost of performance - the compiler puts a small condition at the beginning of each section, which checks, whether the static data or dynamic callback was provided.

The way of dynamic section handling can be changed with sectionDynamic configuration directive and the possible values: OPT_SECTION_COMPILE (default) and OPT_SECTION_RUNTIME.

function dynamicSectionGenerator()
{
	// Section data generator
	return array(0 =>
		array('title' => 'Foo'),
		array('title' => 'Bar'),
		array('title' => 'Joe')
	);	
} // end dynamicSectionGenerator();
	
$tpl -> assignDynamic('dyn', 'dynamicSectionGenerator', array());
$tpl -> parse('template.tpl');