The mystery with the $content variable in Joomla Modules

Question

I am creating a module and inside my module.php file, I created a variable named $content, which I wanted to use later as reference to get values from an associative array.

Getting the values from the array was working fine, but at the same time, I was seeing in the output of my module the value of the $content variable.

I realized that whenever I use a variable named $content inside a module, Joomla var_dumps the value of this variable;

Anyone has any clue about this behavior? Is the $content name somehow reserved - or has any other special purpose?

Answer 1

Yes, $content is used for the module rendering.

Check at /libraries/cms/modules/helper.php line 139 (function renderModule)

Around line 176

    $module->module = preg_replace('/[^A-Z0-9_\.-]/i', '', $module->module);
    $path = JPATH_BASE . '/modules/' . $module->module . '/' . $module->module . '.php';

    // Load the module
    if (file_exists($path))
    {
        $lang = JFactory::getLanguage();

        // 1.5 or Core then 1.6 3PD
        $lang->load($module->module, JPATH_BASE, null, false, true) ||
            $lang->load($module->module, dirname($path), null, false, true);

        $content = '';
        ob_start();
        include $path;
        $module->content = ob_get_contents() . $content;
        ob_end_clean();
    }

$content value is defined here, after loading the template the module output is asigned with

$module->content = ob_get_contents() . $content;