Slim Framework - Routes that call different methods based on query args only

slim_queryarg_route.php

<?php
// http://www.example.com/foo
$app->get('/foo',
    // route middleware throws Pass exception based on query arg variables.
    function() use ($app)
    {
        $getVars = $app->request->params();
        if (isset($getVars['hello']) && ('world' == $getVars['hello']))
        {
            throw new \Slim\Exception\Pass;
        }
    }, function ()
    {
        echo '<p><b>Foo Was Called</b></p>';
    });

// http://www.example.com/foo?hello=world
$app->get('/foo',
    function ()
    {
        echo '<p><b>Hello, World</b></p>';
    });