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Date: Tue, 5 Jan 2021 13:10:58 +0000
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Subject: Re: [PHP-DEV] [RFC] Enumerations, Round 2
From: rowan.collins@gmail.com (Rowan Tommins)

On 04/01/2021 22:04, Mike Schinkel wrote:
> I don't quit get how you are thinking of with ": string"; can you give an example?


The current RFC requires the declaration of a Scalar Enum [1] to include 
the scalar type, so it looks like this:

enum BookingStatus: string {
       case PENDING = "PENDING";
       case CONFIRMED = "CONFIRMED";
       case CANCELLED = "CANCELLED";
}

The simplest opt-in for default scalar values would be to declare the 
type but no values, so the above could be abbreviated this way:

enum BookingStatus: string {
       case PENDING;
       case CONFIRMED;
       case CANCELLED;
}

However, it's probably better to be a bit more explicit, e.g.:

enum BookingStatus: auto string {
       case PENDING;
       case CONFIRMED;
       case CANCELLED;
}

Either way, we'd have to decide if it was allowed to specify some values 
but not all, e.g.:

enum BookingStatus: auto string {
       case PENDING;
       case CONFIRMED;
       case CANCELLED = 'TERMINATED';
}

A more verbose but possibly clearer syntax would be a token on the case 
statements themselves, such as "= auto", to mean "set the value for this 
case based on its constant name":

enum BookingStatus: string {
       case PENDING = auto;
       case CONFIRMED = auto;
       case CANCELLED = 'TERMINATED';
}


There's also the question of whether an automatic value for ints should 
also be allowed, e.g. incrementing in declaration order. This is more 
dangerous, as adding, removing, or re-arranging cases can affect the 
values of *all* the cases in the enum, but is done in some other languages.


[1] https://wiki.php.net/rfc/enumerations#scalar_enums


Regards,

-- 
Rowan Tommins
[IMSoP]