Question

Is it good practice in WordPress to add extra keys to the global array $wp (or any global variable in WordPress for that matter).

I need to access my theme options in all the files in WordPress but I am not sure if this is the best approach.

Something like:

$wp['theme-options] = $theme_options;

Answer 1

What do you mean by ‘all files in WordPress’? If you’re talking about passing variables from your functions/plugin into a template file, those are stored within the global $wp_query object. You can use the get() and set() methods –

function my_plugin(){
    global $wp_query;
    $wp_query->set( 'foo', 'bar' );
}
add_action( 'init', 'plugin' );           // happens early in the logic

function my_plugin_two(){
    global $wp_query;
    $foo = $wp_query->get( 'foo' );
    var_dump( $foo == 'bar' );            // TRUE
}
add_action( 'parse_request', 'plugin' );  // happens later

Then in your template file, you will have $foo all ready to go.

// don't need to reference $wp_query,
// load_template() in wp-includes/template.php has set up the variable for you
get_header();
echo $foo; 
etc