Question

I found many code snippets in Magento such as

$variable_name = Mage::app()->function_name();

here’s an example

$websites = Mage::app()->getWebsites(true, true);

What does this function call (calls?) do? The syntax is unfamiliar, and I need some basic explanation so I can better trace code.

Answer 1

That’s actually two separate method calls.

$result = Mage::app()->getWebsites();

The first is

$o = Mage::app();

This is calling the static method app on “class Mage”, which can be found in

app/Mage.php

The :: operator calls static class methods. If you don’t understand what that means, just think “class on the left, method on the right, and you can’t use a $this variable inside the method”.

So, this method call returns an object, which will almost certainly be a Mage_Core_Model_App, which is at

app/code/core/Mage/Core/Model/App.php

So the one liner above could be rewritten as

$o = Mage::app();
$result = $o->getWebsites();

Hope that helps demystify things a bit.