Passing variable to Magento widget - magento

Question

I'm trying to pass a variable using setData to a box containing a widget with this:
$this->getChild('my_box')->setData('myvar', '123');
echo $this->getChildHtml('my_box');
or this:
echo $this->getChild('my_box')->setData('myvar', '123')->toHtml();
The "my_box" is the block linked with the widget, it's positioned in the footer and defined in local.xml:
<reference name="footer">
<block type="core/text_list" name="my_box" as="my_box" translate="label">
<label>My Box</label>
</block>
</reference>
But if I try to retrieve the value in the widget with any of these methods:
echo $this->getData('myvar');
echo $this->getMyVar();
echo $this->myvar;
there is no return value, any suggestion?

Answer 1

Outside of a rewrite, "core/text_list" is an instance of Mage_Core_Block_Text_List (link) and would not have a template for you to call your code.
You can verify that the basic functionality is working, though:
$my_box = $this->getChild('my_box')->setData('myvar','123'); //if no error, my_box exists!
echo get_class($my_box); //Mage_Core_Block_Text_List
var_dump($my_box->debug()); //array() including 'myvar' => '123'
echo $my_box->getData('myvar')` //correct
echo $my_box->myvar //works, but unconventional
echo $my_box->getMyVar() //will not access the property you set; rather...
echo $my_box->getMyvar() //will work
For other fun, you can set properties via layout XML:
<reference name="footer">
<block type="core/text_list" name="my_box" as="my_box" translate="label">
<label>My Box</label>
<action method="setMyvar">
<arbitrary>123</arbitrary>
</action>
<!-- or <action method="setDatar">
<name>myvar</name>
<val>123</arbitrary>
</action> -->
</block>
</reference>
Also, do be aware the the footer block is permanently cached in the block_html cache by default.