This behavior (get timezone via property) is not expected, you should use `getTimezone()` to retrieve timezone.

Ok then, if they are not intended to be used they both should simply be protected or private properties; however, in this case how are you supposed to access $timezone_type?

If you are writing your own serialization method (or in my case an extension of DateTime) you would have to make an exception for DateTime because even though it has a __set_state() method, that method requires the value of $timezone_type.

See: https://3v4l.org/Klvo3

Ideally DateTimeZone (and possibly DateTime) would have a getTimezoneType() method.

You can get the timezone-type as follows:

$timezone = $date->getTimezone();
$location = $timezone->getLocation();
$type = 2;
if (false !== $location) {
    $type = '3';
}
if (preg_match('/[\+\-]\d{2}:\d{2}/', $timezone->getName())) {
    $type = '1';
}

As a timezone-object sets the timezone type depending on the given value you don't need to set the timezone-type explicitly. 

And when you are extending the DateTime-Class (hopefully DateTimeImmutable but that's a different story) you are free to add a method getTimezoneType using the above code.

The internal properties of the DateTime-Objects are initialized after a var_dump which is a known thing and can not be fixed as easily as it seems. You should under no circumstances depend on them but use the available API.

Have a look at https://3v4l.org/TPWi1

Now I could be mistaken, but I don't see anywhere in the official documentation on how $timezone_type can be determined. Which means this code is relying on the undocumented inner-workings of PHP.

To be clear, I am thankful to you that you have provided a workaround, but that solution would be considered janky at best.

I have no doubt that it works, but because it relies on the undocumented inner-workings of PHP (Which as we all know can and will be updated without notice or being documented on the official pages of PHP.net) it could break at any time with no warning.

Which is why I was hoping to have a method added to DateTimeZone. Honestly, it's kind of surprising to hear these values aren't already stored as properties. I mean I would imagine you have to determine them anyway to initialize the class or change the timezone, so it would simply be a matter of updating the properties when that happens.

Furthermore, this data *appears* to already be stored in C as a property (see "dateobj->time->zone_type" in the source). However, I don't actually know how to program in C so it is very possible I am just misunderstanding this.

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For now, I have opted for calling get_object_vars($this) after the following methods are called: __construct, modify, setTimezone to ensure that $timezone and $timezone_type are always set correctly.