如何从这个对象中检索值？

Using php, I trying to get a particular coupon.

require_once './lib/Stripe.php';
Stripe::setApiKey(STRIPE_SK);
$response = Stripe_Coupon::retrieve('coupon id here');
print_r($response);

print_r($response); gave me the object below. My question is how can retrieve the [id] from the object? Thanks for helping

Stripe_Coupon Object
(
    [_apiKey:protected] => sk_test_xxxxxxxxxxxxxxxxxxxxxxxxxxx
    [_values:protected] => Array
        (
            [id] => 10percent
            [created] => 1395914393
            [percent_off] => 10
            [amount_off] => 
            [currency] => 
            [object] => coupon
            [livemode] => 
            [duration] => repeating
            [redeem_by] => 
            [max_redemptions] => 
            [times_redeemed] => 2
            [duration_in_months] => 12
            [valid] => 1
       )
)

The object is using the PHP magic __get method. You should just be able to use:

$id = $response->id;

If you go through source you see the object eventually comes down to the Stripe_Object class. Source here: https://github.com/stripe/stripe-php/blob/master/lib/Stripe/Object.php