Differences in observer class naming?

Question

When creating an observer you add your model to config.xml like ...

<models>
    <some_name>
        <class>My_Module_Model</class>
    </some_name>
</models>

When adding the event part you can do this

<observers>
    <some_alias>
        <class>some_name/observer</class>
        <method>someMethod</method>
    </some_alias>
</observers>

Or use full class name like

<observers>
    <some_alias>
        <class>My_Module_Model_Observer</class>
        <method>someMethod</method>
    </some_alias>
</observers>

Whats the difference and why should I prefer one over the other?

Answer 1

Thanks Sohel Rana, for pointing to $this->getGroupedClassName('model', $modelClass);

This makes the difference.

Most important lines for this question are:

// First - check maybe the entity class was rewritten
$className = null;
if (isset($config->rewrite->$class)) {
    $className = (string)$config->rewrite->$class;
} else {

If using full class name, rewrites of the related model have no effect. It will load the class that is declared. If using some_name/observer you can rewrite Some_Modules_Model_Observer and the new class is used. Think it's better to use second approach.

Answer 2

There are no big difference when Magento create an object of class tag. Open app/code/core/Mage/Core/Model/Config.php

/**
 * Retrieve module class name
 *
 * @param   sting $modelClass
 * @return  string
 */
public function getModelClassName($modelClass)
{
    $modelClass = trim($modelClass);
    if (strpos($modelClass, '/')===false) {
        return $modelClass;
    }
    return $this->getGroupedClassName('model', $modelClass);
}

Check line if (strpos($modelClass, '/')===false) {

If you pass My_Module_Model_Observer type of name then magento return this without anything.

If you pass some_name/observer then return $this->getGroupedClassName('model', $modelClass); this code create a actual class and return.

So both ways are acceptable and magento standard.