Trouble with Carbons [start/end]OfWeek in Arrays - laravel-5

Question

I have a weird problem. I somehow can't use the above function in an array, but just see my source code:
public function getDeploymentHours($refDate = NULL)
{
if(empty($refDate)){
$refDate = Carbon::now();
} else {
$refDate = new Carbon($refDate);
}
echo $refDate->startOfWeek();
// outputs: 2015-03-16 00:00:00
echo "<br>";
echo $refDate->endOfWeek();
// outputs: 2015-03-22 23:59:59
$a = [$refDate->startOfWeek(),
$refDate->endOfWeek()];
print_r($a);
// outputs: Array
//(
// [0] => Carbon\Carbon Object
// (
// [date] => 2015-03-22 23:59:59
// [timezone_type] => 3
// [timezone] => UTC
// )
// [1] => Carbon\Carbon Object
// (
// [date] => 2015-03-22 23:59:59
// [timezone_type] => 3
// [timezone] => UTC
// )
//)
}
I find that very weird. Can someone imagine how this is possible?

Answer 1

That's because of two reasons.
1. Carbon modifies itself.
When you call startOfWeek(), $refDate actually changes. Not only do you get the new date returned but the changes are set to the actual carbon object so when you could as well do this:
$refDate->startOfWeek();
echo $refDate;
and would get the same result...
2. Carbon returns itself.
Most of Carbons functions actually return the object itself. For example if we track down startOfWeek() it ends up at startOfDay() which looks like this:
public function startOfDay()
{
return $this->hour(0)->minute(0)->second(0);
}
So after all it returns the result of second(0). Which is...
public function second($value)
{
$this->second = $value;
return $this;
}
$this!! So Carbon returns itself.
Conclusion
Because the methods actually change $refDate and the methods return itself you dump the exact same object twice.
Fix
You can simply clone the object instance to have two separate Carbon objects:
$refDate2 = clone $refDate;
$a = [$refDate->startOfWeek(),
$refDate2->endOfWeek()];
print_r($a);