Examples
Example #1 Basic limited values
<?php enum SortOrder { case ASC; case DESC; } function query($fields, $filter, SortOrder $order = SortOrder::ASC) { ... } ?>
The query()
function can now proceed safe in the knowledge that $order
is guaranteed to be either SortOrder::ASC
or SortOrder::DESC
. Any other value would have resulted in a TypeError, so no further error checking or testing is needed.
Example #2 Advanced exclusive values
<?php enum UserStatus: string { case Pending = 'P'; case Active = 'A'; case Suspended = 'S'; case CanceledByUser = 'C'; public function label(): string { return match($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.
<?php foreach (UserStatus::cases() as $case) { printf('<option value="%s">%s</option>\n', $case->value, $case->label()); } ?>
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https://www.php.net/manual/en/language.enumerations.examples.php