(generic) data receiving validation grabber

[Q695]

I'm trying to build a generic data receiving checker.  Here is what I have, but it's not working as you would to verify the variable was passed properly by the client:

function setter($verify, $pass_value){
    if (isset($verify) && $verify!=''){
        $pass_value=$verify;
        echo $pass_value;
        return $pass_value;
    }
}
$_POST['testing'] = "this works";
$verify = '$_POST[\'testing\']';
$pass_value = "\$outputed";
setter($verify, $pass_value);