DateTime as optional parameter (default to "now", not null)?

Question

Is possible to set a DateTime object as optional parameter using now as default?

The following code gives me a syntax error:

public function getData(array $metrics, DateTime $start,
    DateTime $end = new DateTime, $params = array())
{
    // Default DateTime constructor automatically use "now"
}

It's just a matter of curiosity, i know i can do:

public function getData(array $metrics, DateTime $start,
    DateTime $end = null, $params = array())
{
    $end = is_null($end) ? new DateTime() : null;
}

Answer 1

No, you cannot set an object as a default function/method parameter. From the documentation:

Default argument values
A function may define C++-style default values for scalar arguments ...

An object is not a scalar datatype.