_data[] is defined at where in magento?

Question

I saw following codes in header.php,

_data['logo_src']
_data['logo_alt']

Where this are defined? And How I can edit this?

Answer 1

These are the data in Mage_Page_Block_Html_Header Object.

logo_src:

It represent image path for logo which defined from Admin in Logo Image Src Field at System->Configuration->General->Design->Header

logo_alt:

It represent alt text for logo which defined from Admin in Logo Image Alt Field at System->Configuration->General->Design->Header

Values are store in core_cofig_data table with path value design/header/logo_src and design/header/logo_alt respectively ,so to change them pragmatically you can run such code

$store = Mage::app()->getStore();
$code  = $store->getCode();
$config = Mage::getConfig();
$config->setNode("stores/$code/design/header/logo_src", 'value_to_set');