Returning value from callback - php

Question

After registering a new user, I receive a selector and token for account verification.
I want to be able to know whether or not a confirmation mail was sent, but I'm having troubles returning the value from the callback. Here's what I have:
try {
$callback = function ($selector, $token) {
$msg = "some message";
if(mail($_POST['email'],"Please verify your account",$msg))
{
return "success";
}
else
{
return "mail_not_sent";
}
};
$auth->registerWithUniqueUsername($_POST['email'], $_POST['password'], $_POST['username'], $callback);
$output['result']=$callback; //this is the array where I want to store the result in ("success" of "mail_not_sent").
}
catch ($e) {
}

Answer 1

It doesn't look like Auth::registerWithUniqueUsername() gives you access to the result of the callback, so if I had to do this, I would do something like this:
$callback_result = '';
$callback = function ($selector, $token) use (&$callback_result) {
/* Other code here */
$callback_result = 'whatever';
/* Other code here */
};
$auth->registerWithUniqueUsername(/* Other args here */, $callback);
$output['result'] = $callback_result;

Answer 2

This is a bit odd way but:
try {
$mailFlag = null;
$callback = function ($selector, $token) use (&$mailFlag) {
$msg = "some message";
if(mail($_POST['email'],"Please verify your account",$msg))
{
$mailFlag = "success";
}
else
{
$mailFlag = "mail_not_sent";
}
};
$auth->registerWithUniqueUsername($_POST['email'], $_POST['password'], $_POST['username'], $callback);
$output['result'] = $mailFlag; //this is the array where I want to store the result in ("success" of "mail_not_sent").
}
catch ($e) {
}