a simple static class example to set context using cookies.

BMTNContext.php

<?php

final class BMTNContext {

    const COOKIE_NAME = 'bmtn_context';


    private function __construct()
    {
        return FALSE;
    }


    public static function set($context)
    {
        return setcookie(BMTNContext::COOKIE_NAME, $context);
    }


    public static function get()
    {
        if (array_key_exists(BMTNContext::COOKIE_NAME, $_COOKIE))
        {
            return $_COOKIE[BMTNContext::COOKIE_NAME];
        }
        else
        {
            return NULL;
        }
    }


    public static function clear()
    {
        if (array_key_exists(BMTNContext::COOKIE_NAME, $_COOKIE))
        {
            unset($_COOKIE[BMTNContext::COOKIE_NAME]);
        }
        return TRUE;
    }

}


// example useage

BMTNContext::set('category1');

var_dump(BMTNContext::get());    // NOTE: when context is set, it will not be available till the next page load
                                 // because the $_COOKIE superglobal is loaded at the time of page request

// BMTNContext::clear();

// $no_new = new BMTNContext();  // not-allowed / fails