Example #1 Basic limited values
<?phpenum SortOrder{ case Asc; case Desc;}function query($fields, $filter, SortOrder $order = SortOrder::Asc) { ... }?>
The query()
function can now proceed safe in the knowledge that
$order
is guaranteed to be either SortOrder::Asc
or SortOrder::Desc
. Any other value would have resulted in a
TypeError, so no further error checking or testing is needed.
Example #2 Advanced exclusive values
<?phpenum UserStatus: string{ case Pending = 'P'; case Active = 'A'; case Suspended = 'S'; case CanceledByUser = 'C'; public function label(): string { return match($this) { static::Pending => 'Pending', static::Active => 'Active', static::Suspended => 'Suspended', static::CanceledByUser => 'Canceled by user', }; }}?>
In this example, a user's status may be one of, and exclusively, UserStatus::Pending
,
UserStatus::Active
, UserStatus::Suspended
, or
UserStatus::CanceledByUser
. A function can type a parameter against
UserStatus
and then only accept those four values, period.
All four values have a label()
method, which returns a human-readable string.
That string is independent of the "machine name" scalar equivalent string, which can be used in,
for example, a database field or an HTML select box.
<?phpforeach (UserStatus::cases() as $case) { printf('<option value="%s">%s</option>\n', $case->value, $case->label());}?>