## 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) {
                self::Pending => 'Pending',
                self::Active => 'Active',
                self::Suspended => 'Suspended',
                self::CanceledByUser => 'Canceled by user',
            };
        }
    }

    $status = UserStatus::Suspended;
    var_dump($status->label());

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

    enum UserStatus: string
    {
        case Pending = 'P';
        case Active = 'A';
        case Suspended = 'S';
        case CanceledByUser = 'C';

        public function label(): string
        {
            return match($this) {
                self::Pending => 'Pending',
                self::Active => 'Active',
                self::Suspended => 'Suspended',
                self::CanceledByUser => 'Canceled by user',
            };
        }
    }

    foreach (UserStatus::cases() as $case) {
        printf(
            "<option value=\"%s\">%s</option>\n",
            htmlentities($case->value),
            htmlentities($case->label())
        );
    }

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