====== How {{macro}} template gets data for displaying? ======

{{macro}} considers that it works with literal variables or regular arrays. If you pass an object to {{macro}} template, make sure that your object is supports [[http://www.php.net/~helly/php/ext/spl/interfaceArrayAccess.html|ArrayAccess]] or [[http://www.php.net/~helly/php/ext/spl/interfaceIterator.html|Iterator]] interfaces depending on situation.

There are two common ways to get data inside template:
  * **push** - data are pushed into template with some simple interface like set($var, $name) or assign($var, $name). 
  * **pull** - templates gets required data itself by using helpers or callbacks.

{{macro}} supports both these approaches.

===== Push approach =====

lmbMacroTemplate has **set($variable_name, $value)** method that sets a variable $variable_name in template. This variable will be available in template by {$#variable_name} or {$this->variable_name} expressions.

For example:
<code php>
$macro = new lmbMacroTemplate('page.phtml');
$macro->set('title', 'Hello');
</code>
To render 'title' in {{macro}} template we can use to following expression:
<code php>
{$#title}
</code>

There is also lmbMacroTemplate :: **setVars($associative_array)** that is equal to several set() method calls for every element of $associative_array. Note: setVars() removes previously assigned variables.

===== Pull approach =====

You can also use php-blocks right in {{macro}} templates to insert data retrieval operations, e.g.:
<code xml>
<? $products = lmbActiveRecord :: find('Product'); ?>
{{list using='$products' as="$product"}}
<ul>
  {{list:item}}
    <li>{$product.title}</li>
  {{list:item}}
</ul>
{{/list}}
</code>

==== Data from lmbController ====

If you create an application based on WEB_APP package of Limb3, you need to know what template also receives all attributes of currently executed controller just like you called lmbMacroTemplate :: set() for every controller attribute.

For example:
<code php>
class MyController extends lmbController
{
  function doDisplay()
  {
    $this->title = 'Hello';
  }
}
</code>
In the corresponding {{macro}} template $title attribute will be available as:
<code php>
{$#title}
</code>

===== Contexts in {{macro}} =====

{{macro}} have only 2 contexts or data scopes:
  * **global** - scope of the generated php-class of template
  * **local** - scope of one method of this class. 

Rendering is always started from render() method of the generated php-class. Some tags like [[limb3_2007_4:en:packages:macro:tags:core_tags:include_tag|{{include}}]] or [[limb3_2007_4:en:packages:macro:tags:core_tags:apply_tag|{{apply}}]] generate their code into separate methods and thus create other local scopes. {{include}} and {{apply}} allow to pass any variables into their local scopes with any number of extra attributes (see descriptions of these tags).

See also [[expressions|output expressions]].