Mage_Catalog - missing <helpers> config node

Question

In the Mage_Catalog module etc/config.xml there is no config node.

However, catalog helpers can obviously still be loaded via Mage::helper.

How is this possible?

Answer 1

Magento has a fallback on Mage_<your package>_Helper_<your_class>, this means:

Mage::helper('catalog/image') will be resolved to Mage_CATALOG_Helper_IMAGE.

If you don't define your helper in your module, like MyCompany_MyModule, you might have already seen the error:

Class not found: Mage_MyCompany_MyModule_Helper_Data

All this happens here:

\Mage_Core_Model_Config::getGroupedClassName
app/code/core/Mage/Core/Model/Config.php:1254 (EE 1.13.1 (?))
if (empty($className)) {
    $className = 'mage_'.$group.'_'.$groupType;
}