Passing a shortcode attribute to a sub-function

This is both a WordPress and a PHP question, since a PHP programmer may know a technique that the WP group doesn’t.

I have been attempting to write a shortcode that fires the Foundation Reveal code for use inline with the WP Editor. I envision having it work like this:

[reveal size="medium" bg="true" slug="page-slug"]Open a modal with this link![/reveal]

The shortcode specifies the modal size, whether or not to use the black background, and which page slug to incorporate content from in a custom single-page loop (which allows us to use a non-public custom post type to hold the modal data). There are additional attributes but I haven’t written them in yet in the interest of simplicity.

Here’s where it gets tricky.

A modal comes in two parts, the link and the hidden DIV. The DIV typically goes at the footer of the site. I could put it inline and solve my problem, but that would play havoc on Google’s webcache. No, the modal needs to be an aside in the footer.

So I got a bit clever. I had the short code return the target link, but I also had it register a hook (placed in footer.php) to which a content DIV is attached. Everything was working fine until I realized a problem with my variable scope. First, here’s my current code:

/**
 * Foundation Reveal Shortcode
 */

// Create an action to be placed in the site footer. We will target this with the second half of the function
function foundation_reveal() {
    do_action('foundation_reveal');
}

// Set up the shortcode for the modal
function reveal_setup($atts, $content) {

    // Extract the attributes
    extract(shortcode_atts(array(
        'size'  =>  'medium',
        'slug'  =>  'dummy',
        'bg'    =>  'reveal-modal'
    ), $atts));

    $modal_link  = '<a href="#" data-reveal-id="' . $slug . '">';
    $modal_link .= $content;
    $modal_link .= '</a>';

    if ($slug == 'dummy') {
        $the_modal = '<div id="' . $slug . '" class="' . $size . ' ' . $bg . '" data-reveal>' . 'reminder/dummy content goes here' . '</div>';
    } else {
        $the_modal = '<div id="' . $slug . '" class="' . $size . ' ' . $bg . '" data-reveal>' . 'post loop based on page slug goes here' . '</div>';
    }

    function reveal_content($the_modal) {
        echo $the_modal;
    }

    add_action('foundation_reveal', 'reveal_content');

    return $modal_link;
}


/**
 * Setup shortcodes for this theme
 */

// Register all shortcodes
function gmfi_shortcodes() {
    add_shortcode('reveal', 'reveal_setup');
}

// Add shortcodes to the init hoook
add_action( 'init', 'gmfi_shortcodes');

And since it’s kind of helpful to see this whole thing color coded by my IDE, here’s a link to that image.

The problem will be evident to any PHP programmer right away. In order to pass something like $slug to the secondary function, which gets hooked into the footer, I would need to pass the variable by reference.

i.e., I would have to do this:

add_action('foundation_reveal', 'reveal_content($slug)');

That, unfortunately, is not how WordPress works.

So here’s the question then… can you think of another way to pass that variable by reference? Because if not, I may have to suck it up and write a custom hook/action script. That option seems wasteful if there is a way to do it using the available WordPress components. But, then again, if there was another way, one of the WordPress/Foundation plugin suites probably would have done it already.

Either way, I need you all to help me figure out my next step.

Thanks so much for sticking with me as I explained all of that!

Additional note: The foundation_reveal() hook in the footer definitely gets fired, it just doesn’t get any of the class or ID data passed to it.