Question

I am a newbie at PHP; today I see some code as the following in Magento top.phtml.

<?php $_menu = $this->renderCategoriesMenuHtml(0,'level-top') ?>
<?php if($_menu): ?>
<div class="nav-container">
    <ul id="nav">
        <!--NEW HOME LINK -->
        <li class="home"><a href="<?php echo $this->getUrl('') ?>"><?php echo $this->__('Home') ?></a>"</li>
        <!--NEW HOME LINK -->
        <?php echo $_menu ?>
    </ul>
</div>
<?php endif ?>

I know $this is the self of the class, it’s only used in the class to refer to the method or property, on the above code, there is no class has been defined, why it can use $this keyword directly? What does $this->__('Home') stand for?

Answer 1

Since you tagged this magento you likely have a class like Mage_Catalog_Block_Navigation. At least, the methods hint at that. Now, I have no clue about Magento, but this class extends from Mage_Core_Block_Template and in that class you have the fetchView Method, which at some point does

include $includeFilePath;

When you include code inside a method, you do have access to $this in the included file code, because it is evaluated in the scope of that instance:

When a file is included, the code it contains inherits the variable scope of the line on which the include occurs. Any variables available at that line in the calling file will be available within the called file, from that point forward. However, all functions and classes defined in the included file have the global scope.

General Example:

class Template
…
    public function render($templateFile)
    {
        include $templateFile;
    }
    public function ___($stringToTranslate)
    {
        // translates $stringToTranslate somehow
    }
 }

Note that “$this is not the self of the class” is only partially correct. self is also a keyword and php, but while self really refers to the class, $this refers to the instance of a class.